zstd-rs/rust/src/zstd_compress.rs

#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
#![allow(clippy::missing_safety_doc)]
#![allow(clippy::too_many_arguments)]

//! First high-level compression slice.
//!
//! The layout-independent one-shot entry point in this module drives the
//! already migrated compression leaves.  `ZSTD_compressCCtx` uses the same
//! path after a narrow C-owned context reset; public context allocation now
//! runs through a Rust-owned boundary while C retains configuration-dependent
//! private `ZSTD_CCtx_s` initialization.  `ZSTD_compress2` and the complete-input simple
//! `ZSTD_compressStream2(..., ZSTD_e_end)` path dispatch through Rust while
//! retaining the C implementation for advanced and partial-stream cases.

use crate::common::MINMATCH;
use crate::errors::{ERR_isError, ZstdErrorCode, ERROR};
use crate::mem::MEM_writeLE32;
#[cfg(test)]
use crate::xxhash::XXH64_reset;
use crate::xxhash::{XXH64_digest, XXH64_state_t, XXH64_update};
#[cfg(not(test))]
use crate::zstd_compress_api::ZSTD_compressBound;
use crate::zstd_compress_block_split::ZSTD_rust_deriveBlockSplits;
use crate::zstd_compress_frame::{
    write_raw_block, ZSTD_rust_noCompressBlock, ZSTD_rust_rleCompressBlock,
    ZSTD_rust_writeBlockHeader, ZSTD_rust_writeEpilogue, ZSTD_rust_writeFrameHeader,
    ZSTD_writeLastEmptyBlock,
};
use crate::zstd_compress_literals::min_gain;
use crate::zstd_compress_params::{
    ZSTD_compressionParameters, ZSTD_frameParameters, ZSTD_parameters, ZSTD_resolveMaxBlockSize,
    ZSTD_rustMatchStateSizing, ZSTD_rust_params_adjustCParams, ZSTD_rust_params_allocateChainTable,
    ZSTD_rust_params_checkCParams, ZSTD_rust_params_defaultCLevel,
    ZSTD_rust_params_estimateMatchStateSize, ZSTD_rust_params_getParamsInternal,
    ZSTD_rust_params_maxNbSeq, ZSTD_rust_params_rowMatchFinderUsed,
    ZSTD_rust_params_selectBlockCompressor, ZSTD_rust_params_selectCParams,
    ZSTD_RUST_CPM_NO_ATTACH_DICT, ZSTD_RUST_PS_AUTO, ZSTD_RUST_PS_DISABLE, ZSTD_RUST_PS_ENABLE,
};
use crate::zstd_compress_params_api::{
    ZSTD_CCtxParams_setParameter, ZSTD_CCtx_params, ZSTD_customMem, ZSTD_rust_isUpdateAuthorized,
};
use crate::zstd_compress_sequences::SeqDef;
use crate::zstd_compress_stats::{
    update_rep, SeqCollector, SeqStore_t, ZSTD_Sequence, ZSTD_SequencePosition,
    ZSTD_compressedBlockState_t, ZSTD_entropyCTablesMetadata_t, ZSTD_entropyCTables_t,
    ZSTD_rust_confirmRepcodesAndEntropyTables, ZSTD_rust_convertSequencesNoRepcodes,
    ZSTD_rust_copyBlockSequences, ZSTD_rust_countSeqStoreLiteralsBytes,
    ZSTD_rust_countSeqStoreMatchBytes, ZSTD_rust_deriveSeqStoreChunk, ZSTD_rust_determineBlockSize,
    ZSTD_rust_entropyCompressSeqStore, ZSTD_rust_entropyCompressSeqStore_internal,
    ZSTD_rust_fastSequenceLengthSum, ZSTD_rust_finalizeOffBase, ZSTD_rust_get1BlockSummary,
    ZSTD_rust_isRLE, ZSTD_rust_maybeRLE, ZSTD_rust_postProcessSequenceProducerResult,
    ZSTD_rust_resetCompressedBlockState, ZSTD_rust_resetSeqStore,
    ZSTD_rust_seqStore_resolveOffCodes, ZSTD_rust_storeLastLiterals,
    ZSTD_rust_transferSequencesNoDelim, ZSTD_rust_transferSequencesWBlockDelim,
    ZSTD_rust_validateSeqStore, ZSTD_LLT_LITERAL_LENGTH, ZSTD_LLT_MATCH_LENGTH,
};
use crate::zstd_compress_superblock::ZSTD_rust_compressSuperBlock;
use std::ffi::c_void;
use std::mem::{offset_of, size_of, MaybeUninit};
use std::os::raw::{c_int, c_longlong, c_uint};
use std::ptr;

#[cfg(not(test))]
unsafe extern "C" {
    fn ZSTD_createCCtx() -> *mut c_void;
    fn ZSTD_freeCCtx(cctx: *mut c_void) -> usize;
    fn ZSTD_rust_resetCCtxForSimpleCompression(cctx: *mut c_void) -> usize;
    fn ZSTD_rust_prepareCCtxForSimpleCompression(
        cctx: *mut c_void,
        src_size: usize,
        compression_level: c_int,
    ) -> usize;
    fn ZSTD_rust_resetCCtxForSimpleCompressionSession(cctx: *mut c_void) -> usize;
    fn ZSTD_rust_markSimpleCompression2Complete(cctx: *mut c_void);
    fn ZSTD_rust_simpleCompress2Level(cctx: *const c_void, src_size: usize) -> c_int;
    fn ZSTD_compress_usingDict(
        cctx: *mut c_void,
        dst: *mut c_void,
        dst_capacity: usize,
        src: *const c_void,
        src_size: usize,
        dict: *const c_void,
        dict_size: usize,
        compression_level: c_int,
    ) -> usize;
    fn ZSTD_rust_simpleCompressStream2Level(cctx: *const c_void, src_size: usize) -> c_int;
    fn ZSTD_compress2_c(
        cctx: *mut c_void,
        dst: *mut c_void,
        dst_capacity: usize,
        src: *const c_void,
        src_size: usize,
    ) -> usize;
    fn ZSTD_compressStream2_c(
        cctx: *mut c_void,
        output: *mut ZSTD_outBuffer,
        input: *mut ZSTD_inBuffer,
        end_op: c_int,
    ) -> usize;
}

const ZSTD_FAST: c_int = 1;
const ZSTD_DFAST: c_int = 2;
const ZSTD_BTLAZY2: c_int = 6;
const ZSTD_REP_NUM: usize = 3;
const ZSTD_BM_BUFFERED: c_int = 0;
const ZSTD_BM_STABLE: c_int = 1;
const ZSTD_SF_NO_BLOCK_DELIMITERS: c_int = 0;
const ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS: c_int = 1;
const ZSTD_BLOCKSIZE_MAX: usize = 1 << 17;
const ZSTD_CONTENTSIZE_UNKNOWN: u64 = u64::MAX;
const ZSTD_TARGET_CBLOCK_BSS_COMPRESS: c_int = 0;
const ZSTD_BLOCK_HEADER_SIZE: usize = 3;
const MIN_CBLOCK_SIZE: usize = 2;
const MIN_COMPRESSIBLE_BLOCK_SIZE: usize = MIN_CBLOCK_SIZE + ZSTD_BLOCK_HEADER_SIZE + 1 + 1;
const ZSTD_ROWSIZE: usize = 16;
const ZSTD_CSTREAM_STAGE_INIT: c_int = 0;

/// Scalar stream state used to select the complete-input fast path. The C
/// context remains opaque; its private fields are projected before Rust
/// evaluates the eligibility predicate.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_rust_simpleCompressStream2Projection {
    stream_stage: c_int,
    pledged_src_size_plus_one: u64,
    rust_simple_compress2_completed: c_uint,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_simpleCompressStream2Projection, stream_stage) == 0);
    assert!(
        offset_of!(
            ZSTD_rust_simpleCompressStream2Projection,
            pledged_src_size_plus_one
        ) == if size_of::<usize>() == 8 { 8 } else { 4 }
    );
    assert!(
        offset_of!(
            ZSTD_rust_simpleCompressStream2Projection,
            rust_simple_compress2_completed
        ) == if size_of::<usize>() == 8 { 16 } else { 12 }
    );
    assert!(
        size_of::<ZSTD_rust_simpleCompressStream2Projection>()
            == if size_of::<usize>() == 8 { 24 } else { 16 }
    );
};

pub type ZSTD_rust_simpleCompress2LevelFn = unsafe extern "C" fn(*const c_void, usize) -> c_int;

const ZSTD_WINDOW_START_INDEX: u32 = 2;
const ZSTD_DUBT_UNSORTED_MARK: u32 = 1;
const ZSTD_INDEXOVERFLOW_MARGIN: usize = 16usize << 20;
const ZSTD_SHORT_CACHE_TAG_BITS: u32 = 8;
const ZSTD_CURRENT_MAX: usize = if size_of::<usize>() == 8 {
    3500usize << 20
} else {
    2000usize << 20
};
const ZSTD_CHUNKSIZE_MAX: usize = u32::MAX as usize - ZSTD_CURRENT_MAX;
const ZSTD_E_END: c_int = 2;
const ZSTD_E_CONTINUE: c_int = 0;
const ZSTD_E_FLUSH: c_int = 1;
const ZSTD_C_WINDOW_LOG: c_int = 101;
const ZSTD_C_HASH_LOG: c_int = 102;
const ZSTD_C_CHAIN_LOG: c_int = 103;
const ZSTD_C_SEARCH_LOG: c_int = 104;
const ZSTD_C_MIN_MATCH: c_int = 105;
const ZSTD_C_TARGET_LENGTH: c_int = 106;
const ZSTD_C_STRATEGY: c_int = 107;
const ZSTD_C_FORMAT: c_int = 10;
const ZSTD_C_COMPRESSION_LEVEL: c_int = 100;
const ZSTD_C_TARGET_C_BLOCK_SIZE: c_int = 130;
const ZSTD_C_ENABLE_LDM: c_int = 160;
const ZSTD_C_LDM_HASH_LOG: c_int = 161;
const ZSTD_C_LDM_MIN_MATCH: c_int = 162;
const ZSTD_C_LDM_BUCKET_SIZE_LOG: c_int = 163;
const ZSTD_C_LDM_HASH_RATE_LOG: c_int = 164;
const ZSTD_C_CONTENT_SIZE_FLAG: c_int = 200;
const ZSTD_C_CHECKSUM_FLAG: c_int = 201;
const ZSTD_C_DICT_ID_FLAG: c_int = 202;
const ZSTD_C_NB_WORKERS: c_int = 400;
const ZSTD_C_JOB_SIZE: c_int = 401;
const ZSTD_C_OVERLAP_LOG: c_int = 402;
const ZSTD_C_RSYNCABLE: c_int = 500;
const ZSTD_C_FORCE_MAX_WINDOW: c_int = 1000;
const ZSTD_C_FORCE_ATTACH_DICT: c_int = 1001;
const ZSTD_C_LITERAL_COMPRESSION_MODE: c_int = 1002;
const ZSTD_C_SRC_SIZE_HINT: c_int = 1004;
const ZSTD_C_ENABLE_DEDICATED_DICT_SEARCH: c_int = 1005;
const ZSTD_C_STABLE_IN_BUFFER: c_int = 1006;
const ZSTD_C_STABLE_OUT_BUFFER: c_int = 1007;
const ZSTD_C_BLOCK_DELIMITERS: c_int = 1008;
const ZSTD_C_VALIDATE_SEQUENCES: c_int = 1009;
const ZSTD_C_SPLIT_AFTER_SEQUENCES: c_int = 1010;
const ZSTD_C_USE_ROW_MATCH_FINDER: c_int = 1011;
const ZSTD_C_DETERMINISTIC_REF_PREFIX: c_int = 1012;
const ZSTD_C_PREFETCH_CDICT_TABLES: c_int = 1013;
const ZSTD_C_ENABLE_SEQ_PRODUCER_FALLBACK: c_int = 1014;
const ZSTD_C_MAX_BLOCK_SIZE: c_int = 1015;
const ZSTD_C_REPCODE_RESOLUTION: c_int = 1016;
const ZSTD_C_BLOCK_SPLITTER_LEVEL: c_int = 1017;
const ZSTD_RESET_SESSION_ONLY: c_int = 1;
const ZSTD_RESET_PARAMETERS: c_int = 2;
const ZSTD_RESET_SESSION_AND_PARAMETERS: c_int = 3;
const ZSTD_CSTREAM_STAGE_LOAD: c_int = 1;
const ZSTD_CSTREAM_STAGE_FLUSH: c_int = 2;
const ZSTD_BSS_COMPRESS: c_int = 0;
const ZSTD_BSS_NO_COMPRESS: c_int = 1;
const FSE_REPEAT_CHECK: c_int = 1;
const FSE_REPEAT_VALID: c_int = 2;

type FrameChunkPrepareOverflowFn = unsafe extern "C" fn(*mut c_void, *const c_void, usize);
type FrameChunkPrepareWindowFn = unsafe extern "C" fn(*mut c_void, *const c_void, usize, c_uint);
type FrameChunkCompressFn =
    unsafe extern "C" fn(*mut c_void, *mut c_void, usize, *const c_void, usize, c_uint) -> usize;

type BuildSeqStoreSkipFn = unsafe extern "C" fn(*mut c_void, usize);
type BuildSeqStorePrepareFn = unsafe extern "C" fn(*mut c_void, *const c_void, usize);
type BuildSeqStoreCompressFn =
    unsafe extern "C" fn(*mut c_void, *mut SeqStore_t, *mut u32, *const c_void, usize) -> usize;
type BuildSeqStoreTryExternalProducerFn =
    unsafe extern "C" fn(*mut c_void, *const c_void, usize, *mut c_int, *mut c_int) -> usize;
type BuildSeqStoreClearLdmFn = unsafe extern "C" fn(*mut c_void);

type BlockCompressorFn =
    unsafe extern "C" fn(*mut c_void, *mut SeqStore_t, *mut u32, *const c_void, usize) -> usize;

const ZSTD_RUST_BLOCK_COMPRESSOR_TABLE_WIDTH: usize = 10;
const ZSTD_RUST_ROW_BLOCK_COMPRESSOR_TABLE_WIDTH: usize = 3;
const ZSTD_RUST_DICT_MODE_COUNT: c_int = 4;
const ZSTD_RUST_BLOCK_COMPRESSOR_MAX_STRATEGY: c_int =
    ZSTD_RUST_BLOCK_COMPRESSOR_TABLE_WIDTH as c_int - 1;

/// C supplies the configuration-dependent compressor tables and their private
/// match-state leaves. Rust owns the strategy/row-mode index and dictionary
/// mode dispatch into those tables.
#[repr(C)]
pub struct ZSTD_rust_selectBlockCompressorState {
    block_compressors: *const Option<BlockCompressorFn>,
    row_block_compressors: *const Option<BlockCompressorFn>,
    selected_compressor: *mut Option<BlockCompressorFn>,
}

const _: () = {
    assert!(size_of::<BlockCompressorFn>() == size_of::<usize>());
    assert!(size_of::<Option<BlockCompressorFn>>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_selectBlockCompressorState, block_compressors) == 0);
    assert!(
        offset_of!(ZSTD_rust_selectBlockCompressorState, row_block_compressors)
            == size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_selectBlockCompressorState, selected_compressor)
            == 2 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_selectBlockCompressorState>() == 3 * size_of::<usize>());
};

/// Select one C-owned match-state compressor while keeping the table policy
/// and dispatch-index arithmetic in Rust.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_selectBlockCompressor(
    state: *const ZSTD_rust_selectBlockCompressorState,
    strategy: c_int,
    use_row_match_finder: c_int,
    dict_mode: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.block_compressors.is_null()
        || state.row_block_compressors.is_null()
        || state.selected_compressor.is_null()
        || !(ZSTD_FAST..=ZSTD_RUST_BLOCK_COMPRESSOR_MAX_STRATEGY).contains(&strategy)
        || !(0..ZSTD_RUST_DICT_MODE_COUNT).contains(&dict_mode)
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    unsafe { *state.selected_compressor = None };
    let selected_index = ZSTD_rust_params_selectBlockCompressor(strategy, use_row_match_finder);
    let (table, table_width, table_index) = if selected_index < 3 {
        (
            state.row_block_compressors,
            ZSTD_RUST_ROW_BLOCK_COMPRESSOR_TABLE_WIDTH,
            selected_index,
        )
    } else {
        (
            state.block_compressors,
            ZSTD_RUST_BLOCK_COMPRESSOR_TABLE_WIDTH,
            selected_index - 3,
        )
    };
    if table_index < 0 {
        return ERROR(ZstdErrorCode::Generic);
    }

    let callback = unsafe { *table.add(dict_mode as usize * table_width + table_index as usize) };
    let Some(callback) = callback else {
        return ERROR(ZstdErrorCode::Generic);
    };
    unsafe { *state.selected_compressor = Some(callback) };
    0
}

/// Explicit projection for the sequence-store builder.
///
/// Rust owns the threshold/reset/repcode/literal-store orchestration. The
/// callbacks retain the private matchfinder, LDM, and external-producer
/// fallback operations in C without passing `ZSTD_CCtx` across the ABI.
#[repr(C)]
pub struct ZSTD_rust_buildSeqStoreState {
    seq_store: *mut SeqStore_t,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
    callback_context: *mut c_void,
    min_match: c_uint,
    validate_seq_store: c_int,
    skip_small_block: BuildSeqStoreSkipFn,
    prepare_match_state: BuildSeqStorePrepareFn,
    has_external_sequences: c_int,
    ldm_enabled: c_int,
    has_external_sequence_producer: c_int,
    enable_match_finder_fallback: c_int,
    compress_external_sequences: BuildSeqStoreCompressFn,
    compress_ldm: BuildSeqStoreCompressFn,
    try_external_sequence_producer: BuildSeqStoreTryExternalProducerFn,
    compress_internal: BuildSeqStoreCompressFn,
    clear_ldm_seq_store: BuildSeqStoreClearLdmFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_buildSeqStoreState, seq_store) == 0);
    assert!(offset_of!(ZSTD_rust_buildSeqStoreState, prev_c_block) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_buildSeqStoreState, next_c_block) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_buildSeqStoreState, callback_context) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_buildSeqStoreState, min_match) == 4 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, validate_seq_store)
            == 4 * size_of::<usize>() + size_of::<c_uint>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, skip_small_block)
            == 4 * size_of::<usize>() + size_of::<c_uint>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, prepare_match_state)
            == 5 * size_of::<usize>() + size_of::<c_uint>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, has_external_sequences)
            == 6 * size_of::<usize>() + size_of::<c_uint>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, ldm_enabled)
            == 6 * size_of::<usize>() + size_of::<c_uint>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, has_external_sequence_producer)
            == 6 * size_of::<usize>() + size_of::<c_uint>() + 3 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, enable_match_finder_fallback)
            == 6 * size_of::<usize>() + size_of::<c_uint>() + 4 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, compress_external_sequences)
            == 6 * size_of::<usize>() + size_of::<c_uint>() + 5 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, compress_ldm)
            == 7 * size_of::<usize>() + size_of::<c_uint>() + 5 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, try_external_sequence_producer)
            == size_of::<[usize; 8]>() + size_of::<c_uint>() + 5 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, compress_internal)
            == 9 * size_of::<usize>() + size_of::<c_uint>() + 5 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_buildSeqStoreState, clear_ldm_seq_store)
            == 10 * size_of::<usize>() + size_of::<c_uint>() + 5 * size_of::<c_int>()
    );
    assert!(
        size_of::<ZSTD_rust_buildSeqStoreState>()
            == 11 * size_of::<usize>() + size_of::<c_uint>() + 5 * size_of::<c_int>()
    );
};

type ExternalSequenceProducerFn = unsafe extern "C" fn(
    *mut c_void,
    *mut ZSTD_Sequence,
    usize,
    *const c_void,
    usize,
    *const c_void,
    usize,
    c_int,
    usize,
) -> usize;
type ExternalSequenceTransferFn = unsafe extern "C" fn(
    *mut c_void,
    *mut ZSTD_SequencePosition,
    *const ZSTD_Sequence,
    usize,
    *const c_void,
    usize,
) -> usize;

/// Projection for the successful block-level external sequence-producer path.
///
/// Rust owns producer invocation, result post-processing, length validation,
/// and transfer ordering. The transfer callback retains the private CCtx
/// match-state projection; C owns fallback selection after this leaf returns.
#[repr(C)]
pub struct ZSTD_rust_externalSequenceProducerState {
    callback_context: *mut c_void,
    producer_state: *mut c_void,
    producer: Option<ExternalSequenceProducerFn>,
    ext_seq_buf: *mut ZSTD_Sequence,
    ext_seq_buf_capacity: *const usize,
    src: *const c_void,
    src_size: *const usize,
    compression_level: *const c_int,
    window_size: *const usize,
    transfer: Option<ExternalSequenceTransferFn>,
    external_seq_count: *mut usize,
    seq_store_complete: *mut c_int,
    allow_fallback: *mut c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_externalSequenceProducerState, callback_context) == 0);
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, producer_state) == size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, producer) == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, ext_seq_buf) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_externalSequenceProducerState,
            ext_seq_buf_capacity
        ) == 4 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_externalSequenceProducerState, src) == 5 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, src_size) == 6 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, compression_level)
            == 7 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, window_size) == size_of::<[usize; 8]>()
    );
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, transfer) == 9 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, external_seq_count)
            == 10 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, seq_store_complete)
            == 11 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_externalSequenceProducerState, allow_fallback)
            == 12 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_externalSequenceProducerState>() == 13 * size_of::<usize>());
};

/// Try an external sequence producer; C retains only the fallback decision.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_tryExternalSequenceProducer(
    state: *const ZSTD_rust_externalSequenceProducerState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let Some(producer) = state.producer else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(transfer) = state.transfer else {
        return ERROR(ZstdErrorCode::Generic);
    };
    if state.ext_seq_buf.is_null()
        || state.ext_seq_buf_capacity.is_null()
        || state.src.is_null()
        || state.src_size.is_null()
        || state.compression_level.is_null()
        || state.window_size.is_null()
        || state.external_seq_count.is_null()
        || state.seq_store_complete.is_null()
        || state.allow_fallback.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    unsafe {
        *state.seq_store_complete = 0;
        *state.allow_fallback = 0;
    }
    let ext_seq_buf_capacity = unsafe { *state.ext_seq_buf_capacity };
    let src_size = unsafe { *state.src_size };
    let nb_external_seqs = unsafe {
        producer(
            state.producer_state,
            state.ext_seq_buf,
            ext_seq_buf_capacity,
            state.src,
            src_size,
            ptr::null(),
            0,
            *state.compression_level,
            *state.window_size,
        )
    };
    unsafe { *state.external_seq_count = nb_external_seqs };

    let nb_post_processed_seqs = unsafe {
        ZSTD_rust_postProcessSequenceProducerResult(
            state.ext_seq_buf,
            nb_external_seqs,
            ext_seq_buf_capacity,
            src_size,
        )
    };
    if ERR_isError(nb_post_processed_seqs) {
        unsafe { *state.allow_fallback = 1 };
        return nb_post_processed_seqs;
    }

    let seq_len_sum =
        unsafe { ZSTD_rust_fastSequenceLengthSum(state.ext_seq_buf, nb_post_processed_seqs) };
    if seq_len_sum > src_size {
        return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
    }

    let mut seq_pos = ZSTD_SequencePosition::default();
    let transfer_result = unsafe {
        transfer(
            state.callback_context,
            &mut seq_pos,
            state.ext_seq_buf,
            nb_post_processed_seqs,
            state.src,
            src_size,
        )
    };
    if ERR_isError(transfer_result) {
        return transfer_result;
    }

    unsafe { *state.seq_store_complete = 1 };
    0
}

/// Reset the externally referenced raw-sequence store without exposing its C
/// representation to Rust.
#[repr(C)]
pub struct ZSTD_rust_externalSequenceStoreState {
    seq: *mut *mut c_void,
    pos: *mut usize,
    pos_in_sequence: *mut usize,
    size: *mut usize,
    capacity: *mut usize,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_externalSequenceStoreState, seq) == 0);
    assert!(offset_of!(ZSTD_rust_externalSequenceStoreState, pos) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_externalSequenceStoreState, pos_in_sequence) == 2 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_externalSequenceStoreState, size) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_externalSequenceStoreState, capacity) == 4 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_externalSequenceStoreState>() == 5 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_referenceExternalSequences(
    state: *const ZSTD_rust_externalSequenceStoreState,
    seq: *mut c_void,
    nb_seq: usize,
) {
    let Some(state) = state.as_ref() else {
        return;
    };
    if state.seq.is_null()
        || state.pos.is_null()
        || state.pos_in_sequence.is_null()
        || state.size.is_null()
        || state.capacity.is_null()
    {
        return;
    }

    unsafe {
        *state.seq = seq;
        *state.size = nb_seq;
        *state.capacity = nb_seq;
        *state.pos = 0;
        *state.pos_in_sequence = 0;
    }
}

/// C-owned operations used by Rust's frame-chunk block-preparation policy.
///
/// The callback context and private window/workspace layout remain in C; Rust
/// controls the order in which these operations run.
#[repr(C)]
pub struct ZSTD_rust_frameChunkPrepareState {
    callback_context: *mut c_void,
    max_dist: c_uint,
    correct_overflow: FrameChunkPrepareOverflowFn,
    check_dict_validity: FrameChunkPrepareWindowFn,
    enforce_max_dist: FrameChunkPrepareWindowFn,
    clamp_state: *const ZSTD_rust_frameChunkClampState,
}

#[repr(C)]
pub struct ZSTD_rust_frameChunkClampState {
    next_to_update: *mut c_uint,
    low_limit: *const c_uint,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_frameChunkClampState, next_to_update) == 0);
    assert!(offset_of!(ZSTD_rust_frameChunkClampState, low_limit) == size_of::<usize>());
    assert!(size_of::<ZSTD_rust_frameChunkClampState>() == 2 * size_of::<usize>());
};

const _: () = {
    assert!(offset_of!(ZSTD_rust_frameChunkPrepareState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_frameChunkPrepareState, max_dist) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_frameChunkPrepareState, correct_overflow) == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkPrepareState, check_dict_validity) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkPrepareState, enforce_max_dist) == 4 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_frameChunkPrepareState, clamp_state) == 5 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_frameChunkPrepareState>() == 6 * size_of::<usize>());
};

/// Projected inputs shared by the frame-chunk internal block path and the
/// deprecated block adapter.  Sequence-store construction and the private
/// compressed-block storage remain behind these two C-owned projections.
#[repr(C)]
pub struct ZSTD_rust_compressContinueBlockState {
    build_seq_store_state: *const ZSTD_rust_buildSeqStoreState,
    block_internal_state: *const ZSTD_rust_blockInternalState,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressContinueBlockState, build_seq_store_state) == 0);
    assert!(
        offset_of!(ZSTD_rust_compressContinueBlockState, block_internal_state)
            == size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_compressContinueBlockState>() == 2 * size_of::<usize>());
};

/// Explicit projection of the state used by the block-split estimator.
///
/// C retains the private block-split context and owns projection assembly;
/// Rust owns the estimator implementation and receives only its required
/// sequence stores, entropy tables, parameters, and workspace.
#[repr(C)]
pub struct ZSTD_rust_deriveBlockSplitsState {
    original_seq_store: *const SeqStore_t,
    full_seq_store_chunk: *mut SeqStore_t,
    first_half_seq_store: *mut SeqStore_t,
    second_half_seq_store: *mut SeqStore_t,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
    entropy_metadata: *mut ZSTD_entropyCTablesMetadata_t,
    workspace: *mut c_void,
    workspace_size: usize,
    strategy: c_int,
    disable_literal_compression: c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_deriveBlockSplitsState, original_seq_store) == 0);
    assert!(
        offset_of!(ZSTD_rust_deriveBlockSplitsState, full_seq_store_chunk) == size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_deriveBlockSplitsState, first_half_seq_store)
            == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_deriveBlockSplitsState, second_half_seq_store)
            == 3 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_deriveBlockSplitsState, prev_c_block) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_deriveBlockSplitsState, next_c_block) == 5 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_deriveBlockSplitsState, entropy_metadata) == 6 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_deriveBlockSplitsState, workspace) == 7 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_deriveBlockSplitsState, workspace_size) == usize::BITS as usize);
    assert!(
        offset_of!(ZSTD_rust_deriveBlockSplitsState, strategy)
            == usize::BITS as usize + size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_deriveBlockSplitsState,
            disable_literal_compression
        ) == usize::BITS as usize + size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        size_of::<ZSTD_rust_deriveBlockSplitsState>()
            == usize::BITS as usize + size_of::<usize>() + 2 * size_of::<c_int>()
    );
};

/// Explicit projection of the state used by `ZSTD_compress_frameChunk`.
///
/// The Rust side owns the per-frame block loop and its savings/dispatch
/// policy.  The callback context is opaque to Rust and is only returned to
/// C-owned callbacks, which retain private window, workspace, and CCtx
/// layout-sensitive operations.
#[repr(C)]
pub struct ZSTD_rust_frameChunkState {
    callback_context: *mut c_void,
    tmp_workspace: *mut c_void,
    checksum_state: *mut XXH64_state_t,
    is_first_block: *mut c_int,
    stage: *mut c_int,
    tmp_wksp_size: usize,
    block_size_max: usize,
    savings: c_longlong,
    pre_block_splitter_level: c_int,
    strategy: c_int,
    use_target_c_block_size: c_int,
    block_splitter_enabled: c_int,
    checksum_flag: c_int,
    ending_stage: c_int,
    prepare_state: *const ZSTD_rust_frameChunkPrepareState,
    compress_target: Option<FrameChunkCompressFn>,
    compress_split: Option<FrameChunkCompressFn>,
    compress_internal: Option<FrameChunkCompressFn>,
    compress_internal_state: *const ZSTD_rust_compressContinueBlockState,
    compress_target_state: *const ZSTD_rust_targetCBlockSizeState,
    compress_split_state: *const ZSTD_rust_splitBlockState,
    derive_block_splits_state: *const ZSTD_rust_deriveBlockSplitsState,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_frameChunkState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_frameChunkState, tmp_workspace) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_frameChunkState, checksum_state) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_frameChunkState, is_first_block) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_frameChunkState, stage) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_frameChunkState, tmp_wksp_size) == 5 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_frameChunkState, block_size_max) == 6 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_frameChunkState, savings) == 7 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, pre_block_splitter_level)
            == 7 * size_of::<usize>() + size_of::<c_longlong>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, strategy)
            == 7 * size_of::<usize>() + size_of::<c_longlong>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, use_target_c_block_size)
            == 7 * size_of::<usize>() + size_of::<c_longlong>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, block_splitter_enabled)
            == 7 * size_of::<usize>() + size_of::<c_longlong>() + 3 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, checksum_flag)
            == 7 * size_of::<usize>() + size_of::<c_longlong>() + 4 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, ending_stage)
            == 7 * size_of::<usize>() + size_of::<c_longlong>() + 5 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, prepare_state)
            == 7 * size_of::<usize>() + size_of::<c_longlong>() + 6 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, compress_internal_state)
            == 11 * size_of::<usize>() + size_of::<c_longlong>() + 6 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, compress_target_state)
            == 12 * size_of::<usize>() + size_of::<c_longlong>() + 6 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, compress_split_state)
            == 13 * size_of::<usize>() + size_of::<c_longlong>() + 6 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_frameChunkState, derive_block_splits_state)
            == 14 * size_of::<usize>() + size_of::<c_longlong>() + 6 * size_of::<c_int>()
    );
    assert!(
        size_of::<ZSTD_rust_frameChunkState>()
            == 15 * size_of::<usize>() + size_of::<c_longlong>() + 6 * size_of::<c_int>()
    );
};

/// Rust implementation of `ZSTD_compress_frameChunk`.
///
/// C still owns the private match-state/window operations and invokes the
/// selected block body through callbacks. Rust owns preparation ordering, the
/// block-size heuristic call, output framing, savings accounting, checksum
/// sequencing, and frame-state update.
#[inline]
unsafe fn prepare_frame_chunk_block(
    state: &ZSTD_rust_frameChunkPrepareState,
    src: *const c_void,
    block_size: usize,
) {
    unsafe { (state.correct_overflow)(state.callback_context, src, block_size) };
    unsafe { (state.check_dict_validity)(state.callback_context, src, block_size, state.max_dist) };
    unsafe { (state.enforce_max_dist)(state.callback_context, src, block_size, state.max_dist) };
    if state.clamp_state.is_null() {
        return;
    }
    let clamp_state = unsafe { &*state.clamp_state };
    if clamp_state.next_to_update.is_null() || clamp_state.low_limit.is_null() {
        return;
    }
    unsafe {
        /* Ensure hash/chain table insertion resumes no sooner than lowlimit. */
        if *clamp_state.next_to_update < *clamp_state.low_limit {
            *clamp_state.next_to_update = *clamp_state.low_limit;
        }
    }
}

#[allow(clippy::too_many_arguments)]
unsafe fn compress_frame_chunk_body_with(
    state: &ZSTD_rust_frameChunkState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    last_frame_chunk: c_uint,
) -> usize {
    if state.is_first_block.is_null() || state.stage.is_null() || state.prepare_state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    if state.checksum_flag != 0 && src_size != 0 {
        if state.checksum_state.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        unsafe {
            let _ = XXH64_update(state.checksum_state, src, src_size);
        }
    }

    let mut remaining = src_size;
    let mut ip = src.cast::<u8>();
    let mut op = dst.cast::<u8>();
    let mut remaining_capacity = dst_capacity;
    let mut savings = state.savings;
    let mut compressed_size_total = 0usize;

    while remaining != 0 {
        let block_size = unsafe {
            crate::zstd_compress_frame::ZSTD_rust_optimalBlockSize(
                ip.cast(),
                remaining,
                state.block_size_max,
                state.pre_block_splitter_level,
                state.strategy,
                savings,
                state.tmp_workspace,
                state.tmp_wksp_size,
            )
        };
        if block_size == 0 || block_size > remaining {
            return ERROR(ZstdErrorCode::Generic);
        }

        let last_block = last_frame_chunk & u32::from(block_size == remaining);

        /* Keep the original early capacity guard: even a raw block needs the
         * minimum block header plus the minimum compressible payload budget. */
        if remaining_capacity < ZSTD_BLOCK_HEADER_SIZE + MIN_CBLOCK_SIZE + 1 {
            return ERROR(ZstdErrorCode::DstSizeTooSmall);
        }

        unsafe { prepare_frame_chunk_block(&*state.prepare_state, ip.cast(), block_size) };

        let c_size = if state.use_target_c_block_size != 0 {
            if !state.compress_target_state.is_null() {
                let block_state = if state.compress_internal_state.is_null() {
                    return ERROR(ZstdErrorCode::Generic);
                } else {
                    unsafe { &*state.compress_internal_state }
                };
                if block_state.build_seq_store_state.is_null() {
                    return ERROR(ZstdErrorCode::Generic);
                }
                let bss = unsafe {
                    ZSTD_rust_buildSeqStore(
                        block_state.build_seq_store_state,
                        ip.cast(),
                        block_size,
                    )
                };
                if ERR_isError(bss) {
                    return bss;
                }
                let mut target_state = unsafe { ptr::read(state.compress_target_state) };
                target_state.is_first_block = unsafe { *state.is_first_block };
                unsafe {
                    ZSTD_rust_compressBlockTargetCBlockSizeAfterBuild(
                        &target_state,
                        op.cast(),
                        remaining_capacity,
                        ip.cast(),
                        block_size,
                        bss as c_int,
                        last_block,
                    )
                }
            } else {
                let Some(compress_target) = state.compress_target else {
                    return ERROR(ZstdErrorCode::Generic);
                };
                unsafe {
                    compress_target(
                        state.callback_context,
                        op.cast(),
                        remaining_capacity,
                        ip.cast(),
                        block_size,
                        last_block,
                    )
                }
            }
        } else if state.block_splitter_enabled != 0 {
            if !state.compress_split_state.is_null() {
                let block_state = if state.compress_internal_state.is_null() {
                    return ERROR(ZstdErrorCode::Generic);
                } else {
                    unsafe { &*state.compress_internal_state }
                };
                let split_state = unsafe { &*state.compress_split_state };
                if block_state.build_seq_store_state.is_null() {
                    return ERROR(ZstdErrorCode::Generic);
                }
                let bss = unsafe {
                    ZSTD_rust_buildSeqStore(
                        block_state.build_seq_store_state,
                        ip.cast(),
                        block_size,
                    )
                };
                if ERR_isError(bss) {
                    return bss;
                }
                let num_splits = if bss == ZSTD_BSS_COMPRESS as usize {
                    if split_state.seq_store.is_null() || split_state.partitions.is_null() {
                        return ERROR(ZstdErrorCode::Generic);
                    }
                    let sequence_store = unsafe { &*split_state.seq_store };
                    if sequence_store.sequencesStart.is_null() || sequence_store.sequences.is_null()
                    {
                        return ERROR(ZstdErrorCode::Generic);
                    }
                    let sequence_count = unsafe {
                        sequence_store
                            .sequences
                            .offset_from(sequence_store.sequencesStart)
                    };
                    if sequence_count < 0 {
                        return ERROR(ZstdErrorCode::Generic);
                    }
                    if state.derive_block_splits_state.is_null() {
                        return ERROR(ZstdErrorCode::Generic);
                    }
                    let derive_state = unsafe { &*state.derive_block_splits_state };
                    if derive_state.original_seq_store.is_null()
                        || derive_state.full_seq_store_chunk.is_null()
                        || derive_state.first_half_seq_store.is_null()
                        || derive_state.second_half_seq_store.is_null()
                        || derive_state.prev_c_block.is_null()
                        || derive_state.next_c_block.is_null()
                        || derive_state.entropy_metadata.is_null()
                    {
                        return ERROR(ZstdErrorCode::Generic);
                    }
                    let prev_c_block = unsafe { *derive_state.prev_c_block };
                    let next_c_block = unsafe { *derive_state.next_c_block };
                    if prev_c_block.is_null() || next_c_block.is_null() {
                        return ERROR(ZstdErrorCode::Generic);
                    }
                    let result = unsafe {
                        ZSTD_rust_deriveBlockSplits(
                            split_state.partitions.cast_mut(),
                            sequence_count as u32,
                            derive_state.original_seq_store,
                            derive_state.full_seq_store_chunk,
                            derive_state.first_half_seq_store,
                            derive_state.second_half_seq_store,
                            ptr::addr_of!((*prev_c_block).entropy),
                            ptr::addr_of_mut!((*next_c_block).entropy),
                            derive_state.strategy,
                            derive_state.disable_literal_compression,
                            derive_state.entropy_metadata,
                            derive_state.workspace,
                            derive_state.workspace_size,
                        )
                    };
                    if ERR_isError(result) {
                        return result;
                    }
                    result
                } else {
                    0
                };
                let mut split_state = unsafe { ptr::read(state.compress_split_state) };
                split_state.is_first_block = unsafe { *state.is_first_block };
                unsafe {
                    ZSTD_rust_compressBlockSplitAfterBuild(
                        &split_state,
                        op.cast(),
                        remaining_capacity,
                        ip.cast(),
                        block_size,
                        last_block,
                        num_splits,
                        bss as c_int,
                    )
                }
            } else {
                let Some(compress_split) = state.compress_split else {
                    return ERROR(ZstdErrorCode::Generic);
                };
                unsafe {
                    compress_split(
                        state.callback_context,
                        op.cast(),
                        remaining_capacity,
                        ip.cast(),
                        block_size,
                        last_block,
                    )
                }
            }
        } else {
            let compressed_size = if !state.compress_internal_state.is_null() {
                unsafe {
                    ZSTD_rust_compressFrameChunkInternal(
                        state.compress_internal_state,
                        state.is_first_block,
                        op.add(ZSTD_BLOCK_HEADER_SIZE).cast(),
                        remaining_capacity - ZSTD_BLOCK_HEADER_SIZE,
                        ip.cast(),
                        block_size,
                        last_block,
                    )
                }
            } else {
                let Some(compress_internal) = state.compress_internal else {
                    return ERROR(ZstdErrorCode::Generic);
                };
                unsafe {
                    compress_internal(
                        state.callback_context,
                        op.add(ZSTD_BLOCK_HEADER_SIZE).cast(),
                        remaining_capacity - ZSTD_BLOCK_HEADER_SIZE,
                        ip.cast(),
                        block_size,
                        last_block,
                    )
                }
            };
            if ERR_isError(compressed_size) {
                return compressed_size;
            }

            if compressed_size == 0 {
                unsafe {
                    ZSTD_rust_noCompressBlock(
                        op.cast(),
                        remaining_capacity,
                        ip.cast(),
                        block_size,
                        last_block,
                    )
                }
            } else {
                unsafe {
                    ZSTD_rust_writeBlockHeader(op.cast(), compressed_size, block_size, last_block)
                };
                compressed_size + ZSTD_BLOCK_HEADER_SIZE
            }
        };

        if ERR_isError(c_size) {
            return c_size;
        }

        savings =
            savings.wrapping_add((block_size as c_longlong).wrapping_sub(c_size as c_longlong));
        unsafe {
            ip = ip.add(block_size);
            op = op.add(c_size);
        }
        remaining -= block_size;
        debug_assert!(c_size <= remaining_capacity);
        remaining_capacity = remaining_capacity.wrapping_sub(c_size);
        compressed_size_total = compressed_size_total.wrapping_add(c_size);
        unsafe { *state.is_first_block = 0 };
    }

    if last_frame_chunk != 0 && compressed_size_total != 0 {
        unsafe { *state.stage = state.ending_stage };
    }
    compressed_size_total
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressFrameChunk(
    state: *const ZSTD_rust_frameChunkState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    last_frame_chunk: c_uint,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_frame_chunk_body_with(&*state, dst, dst_capacity, src, src_size, last_frame_chunk)
    }
}

type CompressContinueBlockFn =
    unsafe extern "C" fn(*mut c_void, *mut c_void, usize, *const c_void, usize, c_uint) -> usize;

/// Pointer projection for one C-owned `ZSTD_window_t` and the match-state
/// fields which follow its update.  Each field points directly at the C
/// storage so later callbacks observe the updated window immediately.
#[repr(C)]
#[derive(Default)]
struct ZSTD_rust_compressContinueWindowProjection {
    next_src: *mut *const c_void,
    base: *mut *const c_void,
    dict_base: *mut *const c_void,
    dict_limit: *mut c_uint,
    low_limit: *mut c_uint,
    force_non_contiguous: *mut c_int,
    next_to_update: *mut c_uint,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressContinueWindowProjection, next_src) == 0);
    assert!(offset_of!(ZSTD_rust_compressContinueWindowProjection, base) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressContinueWindowProjection, dict_base) == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueWindowProjection, dict_limit)
            == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueWindowProjection, low_limit) == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_compressContinueWindowProjection,
            force_non_contiguous
        ) == 5 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueWindowProjection, next_to_update)
            == 6 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_compressContinueWindowProjection>() == 7 * size_of::<usize>());
};

/// Explicit projection for the high-level continue and deprecated block APIs.
///
/// Rust owns stage transitions, frame-header sequencing, input progression,
/// and dispatch between the already-migrated frame-chunk/block bodies.  The
/// frame-header parameters and frame-chunk state are projected explicitly.
/// The opaque callback context remains in C for overflow-correction callbacks
/// and context-sensitive block operations; window advancement is projected
/// directly into Rust.
#[repr(C)]
pub struct ZSTD_rust_compressContinueState {
    callback_context: *mut c_void,
    window_state: *const ZSTD_rust_compressContinueWindowProjection,
    ldm_window_state: *const ZSTD_rust_compressContinueWindowProjection,
    overflow_state: *const ZSTD_rust_overflowCorrectState,
    frame_chunk_state: *const ZSTD_rust_frameChunkState,
    compress_block: CompressContinueBlockFn,
    stage: *mut c_int,
    consumed_src_size: *mut u64,
    produced_c_size: *mut u64,
    pledged_src_size_plus_one: u64,
    block_size_max: usize,
    check_block_size: c_int,
    no_dict_id_flag: c_int,
    checksum_flag: c_int,
    content_size_flag: c_int,
    format: c_int,
    window_log: c_uint,
    dict_id: c_uint,
    ldm_enabled: c_int,
}

const COMPRESS_CONTINUE_SCALARS_OFFSET: usize =
    size_of::<[usize; 9]>() + size_of::<u64>() + size_of::<usize>();

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressContinueState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_compressContinueState, window_state) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, ldm_window_state) == 2 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_compressContinueState, overflow_state) == 3 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, frame_chunk_state) == 4 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_compressContinueState, compress_block) == 5 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressContinueState, stage) == 6 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, consumed_src_size) == 7 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, produced_c_size)
            == 8 * (usize::BITS as usize / 8)
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, pledged_src_size_plus_one)
            == size_of::<[usize; 9]>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, block_size_max)
            == size_of::<[usize; 9]>() + size_of::<u64>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, check_block_size)
            == COMPRESS_CONTINUE_SCALARS_OFFSET
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, no_dict_id_flag)
            == COMPRESS_CONTINUE_SCALARS_OFFSET + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, checksum_flag)
            == COMPRESS_CONTINUE_SCALARS_OFFSET + size_of::<[c_int; 2]>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, content_size_flag)
            == COMPRESS_CONTINUE_SCALARS_OFFSET + size_of::<[c_int; 3]>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, format)
            == COMPRESS_CONTINUE_SCALARS_OFFSET + size_of::<[c_int; 4]>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, window_log)
            == COMPRESS_CONTINUE_SCALARS_OFFSET + size_of::<[c_int; 5]>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, dict_id)
            == COMPRESS_CONTINUE_SCALARS_OFFSET + size_of::<[c_int; 5]>() + size_of::<c_uint>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressContinueState, ldm_enabled)
            == COMPRESS_CONTINUE_SCALARS_OFFSET + size_of::<[c_int; 5]>() + 2 * size_of::<c_uint>()
    );
    assert!(
        size_of::<ZSTD_rust_compressContinueState>()
            == if size_of::<usize>() == 8 { 120 } else { 80 }
    );
};

const ZSTD_COMPRESSION_STAGE_CREATED: c_int = 0;
const ZSTD_COMPRESSION_STAGE_INIT: c_int = 1;
const ZSTD_COMPRESSION_STAGE_ONGOING: c_int = 2;
#[cfg(test)]
const ZSTD_COMPRESSION_STAGE_ENDING: c_int = 3;

type GenerateSequencesGetParameterFn =
    unsafe extern "C" fn(*mut c_void, c_int, *mut c_int) -> usize;
type GenerateSequencesAllocateFn = unsafe extern "C" fn(*mut c_void, usize) -> *mut c_void;
type GenerateSequencesFreeFn = unsafe extern "C" fn(*mut c_void, *mut c_void);
type GenerateSequencesSetCollectorFn =
    unsafe extern "C" fn(*mut c_void, *mut ZSTD_Sequence, usize) -> usize;
type GenerateSequencesCompress2Fn =
    unsafe extern "C" fn(*mut c_void, *mut c_void, usize, *const c_void, usize) -> usize;
type GenerateSequencesGetCountFn = unsafe extern "C" fn(*mut c_void) -> usize;

/// C-owned context projection for `ZSTD_generateSequences()`.
///
/// Rust owns the public policy and temporary-buffer lifetime. C callbacks keep
/// the private `ZSTD_CCtx` and `SeqCollector` layouts out of this module.
#[repr(C)]
pub struct ZSTD_rust_generateSequencesState {
    callback_context: *mut c_void,
    get_parameter: GenerateSequencesGetParameterFn,
    allocate: GenerateSequencesAllocateFn,
    free: GenerateSequencesFreeFn,
    set_collector: GenerateSequencesSetCollectorFn,
    compress2: GenerateSequencesCompress2Fn,
    get_count: GenerateSequencesGetCountFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_generateSequencesState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_generateSequencesState, get_parameter) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_generateSequencesState, allocate) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_generateSequencesState, free) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_generateSequencesState, set_collector) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_generateSequencesState, compress2) == 5 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_generateSequencesState, get_count) == 6 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_generateSequencesState>() == 7 * size_of::<usize>());
};

/// Own the validation, allocation, collection setup, compression call, and
/// cleanup ordering for the public sequence-generation API.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_generateSequences(
    state: *const ZSTD_rust_generateSequencesState,
    out_seqs: *mut ZSTD_Sequence,
    out_seqs_size: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let dst_capacity = crate::zstd_compress_api::ZSTD_compressBound(src_size);
    let mut parameter = 0;

    let result = unsafe {
        (state.get_parameter)(
            state.callback_context,
            ZSTD_C_TARGET_C_BLOCK_SIZE,
            &mut parameter,
        )
    };
    if ERR_isError(result) {
        return result;
    }
    if parameter != 0 {
        return ERROR(ZstdErrorCode::ParameterUnsupported);
    }

    let result =
        unsafe { (state.get_parameter)(state.callback_context, ZSTD_C_NB_WORKERS, &mut parameter) };
    if ERR_isError(result) {
        return result;
    }
    if parameter != 0 {
        return ERROR(ZstdErrorCode::ParameterUnsupported);
    }

    let dst = unsafe { (state.allocate)(state.callback_context, dst_capacity) };
    if dst.is_null() {
        return ERROR(ZstdErrorCode::MemoryAllocation);
    }

    let result = unsafe { (state.set_collector)(state.callback_context, out_seqs, out_seqs_size) };
    if ERR_isError(result) {
        unsafe { (state.free)(state.callback_context, dst) };
        return result;
    }

    let result =
        unsafe { (state.compress2)(state.callback_context, dst, dst_capacity, src, src_size) };
    unsafe { (state.free)(state.callback_context, dst) };
    if ERR_isError(result) {
        return result;
    }

    let sequence_count = unsafe { (state.get_count)(state.callback_context) };
    debug_assert!(sequence_count <= crate::zstd_compress_api::ZSTD_sequenceBound(src_size));
    sequence_count
}

#[inline]
unsafe fn compress_continue_block_body_with(
    state: &ZSTD_rust_compressContinueBlockState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    frame: c_uint,
    is_first_block: *const c_int,
) -> usize {
    if state.build_seq_store_state.is_null() || state.block_internal_state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let bss = unsafe { ZSTD_rust_buildSeqStore(state.build_seq_store_state, src, src_size) };
    if ERR_isError(bss) {
        return bss;
    }
    if !is_first_block.is_null() {
        let mut block_state = unsafe { ptr::read(state.block_internal_state) };
        block_state.is_first_block = unsafe { *is_first_block };
        return unsafe {
            ZSTD_rust_compressBlockInternalAfterBuild(
                &block_state,
                dst,
                dst_capacity,
                src,
                src_size,
                frame,
                bss as c_int,
            )
        };
    }
    unsafe {
        ZSTD_rust_compressBlockInternalAfterBuild(
            state.block_internal_state,
            dst,
            dst_capacity,
            src,
            src_size,
            frame,
            bss as c_int,
        )
    }
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressContinueBlock(
    context: *mut c_void,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    _last_frame_chunk: c_uint,
) -> usize {
    if context.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*context.cast::<ZSTD_rust_compressContinueBlockState>() };
    unsafe {
        compress_continue_block_body_with(state, dst, dst_capacity, src, src_size, 0, ptr::null())
    }
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressFrameChunkInternal(
    state: *const ZSTD_rust_compressContinueBlockState,
    is_first_block: *const c_int,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    _last_block: c_uint,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_continue_block_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            src_size,
            1,
            is_first_block,
        )
    }
}

unsafe fn compress_continue_update_window(
    projection: *const ZSTD_rust_compressContinueWindowProjection,
    src: *const c_void,
    src_size: usize,
    force_non_contiguous: c_int,
    update_match_state: bool,
) -> Result<(), usize> {
    if projection.is_null() {
        return Err(ERROR(ZstdErrorCode::Generic));
    }
    let projection = unsafe { &*projection };
    if projection.next_src.is_null()
        || projection.base.is_null()
        || projection.dict_base.is_null()
        || projection.dict_limit.is_null()
        || projection.low_limit.is_null()
    {
        return Err(ERROR(ZstdErrorCode::Generic));
    }
    if update_match_state
        && (projection.force_non_contiguous.is_null() || projection.next_to_update.is_null())
    {
        return Err(ERROR(ZstdErrorCode::Generic));
    }

    let mut window_state = ZSTD_rust_windowUpdateState {
        nextSrc: unsafe { *projection.next_src },
        base: unsafe { *projection.base },
        dictBase: unsafe { *projection.dict_base },
        dictLimit: unsafe { *projection.dict_limit },
        lowLimit: unsafe { *projection.low_limit },
    };
    let contiguous =
        unsafe { ZSTD_rust_windowUpdate(&mut window_state, src, src_size, force_non_contiguous) };
    unsafe {
        *projection.next_src = window_state.nextSrc;
        *projection.base = window_state.base;
        *projection.dict_base = window_state.dictBase;
        *projection.dict_limit = window_state.dictLimit;
        *projection.low_limit = window_state.lowLimit;
    }
    if update_match_state && contiguous == 0 {
        unsafe {
            *projection.force_non_contiguous = 0;
            *projection.next_to_update = window_state.dictLimit;
        }
    }
    Ok(())
}

#[allow(clippy::too_many_arguments)]
unsafe fn compress_continue_body_with(
    state: &ZSTD_rust_compressContinueState,
    mut dst: *mut c_void,
    mut dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    frame: c_uint,
    last_frame_chunk: c_uint,
) -> usize {
    if state.stage.is_null() || state.consumed_src_size.is_null() || state.produced_c_size.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    /* The deprecated block entry point performed this check before entering
     * the old internal routine. Keep that ordering in the Rust orchestration. */
    if state.check_block_size != 0 && src_size > state.block_size_max {
        return ERROR(ZstdErrorCode::SrcSizeWrong);
    }

    if unsafe { *state.stage } == ZSTD_COMPRESSION_STAGE_CREATED {
        return ERROR(ZstdErrorCode::StageWrong);
    }

    let mut frame_header_size = 0usize;
    if frame != 0 && unsafe { *state.stage } == ZSTD_COMPRESSION_STAGE_INIT {
        frame_header_size = unsafe {
            ZSTD_rust_writeFrameHeader(
                dst,
                dst_capacity,
                state.no_dict_id_flag,
                state.checksum_flag,
                state.content_size_flag,
                state.format,
                state.window_log,
                state.pledged_src_size_plus_one.wrapping_sub(1),
                state.dict_id,
            )
        };
        if ERR_isError(frame_header_size) {
            return frame_header_size;
        }
        if frame_header_size > dst_capacity {
            return ERROR(ZstdErrorCode::DstSizeTooSmall);
        }
        unsafe {
            *state.stage = ZSTD_COMPRESSION_STAGE_ONGOING;
        }
        dst = unsafe { dst.cast::<u8>().add(frame_header_size).cast() };
        dst_capacity -= frame_header_size;
    }

    if src_size == 0 {
        return frame_header_size;
    }

    if state.window_state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let match_window = unsafe { &*state.window_state };
    if match_window.force_non_contiguous.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let force_non_contiguous = unsafe { *match_window.force_non_contiguous };
    if let Err(result) = unsafe {
        compress_continue_update_window(
            state.window_state,
            src,
            src_size,
            force_non_contiguous,
            true,
        )
    } {
        return result;
    }
    if state.ldm_enabled != 0 {
        if let Err(result) = unsafe {
            compress_continue_update_window(state.ldm_window_state, src, src_size, 0, false)
        } {
            return result;
        }
    }
    if frame == 0 {
        if state.overflow_state.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        let src_end = src.cast::<u8>().wrapping_add(src_size).cast();
        unsafe { ZSTD_rust_overflowCorrectIfNeeded(state.overflow_state, src, src_end) };
    }

    let compressed_size = if frame != 0 {
        if state.frame_chunk_state.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        unsafe {
            ZSTD_rust_compressFrameChunk(
                state.frame_chunk_state,
                dst,
                dst_capacity,
                src,
                src_size,
                last_frame_chunk,
            )
        }
    } else {
        unsafe {
            (state.compress_block)(state.callback_context, dst, dst_capacity, src, src_size, 0)
        }
    };
    if ERR_isError(compressed_size) {
        return compressed_size;
    }

    let source_size_wrong = update_frame_progression(
        unsafe { &mut *state.consumed_src_size },
        unsafe { &mut *state.produced_c_size },
        state.pledged_src_size_plus_one,
        src_size,
        compressed_size,
        frame_header_size,
    );
    if state.pledged_src_size_plus_one != 0 && source_size_wrong {
        return ERROR(ZstdErrorCode::SrcSizeWrong);
    }
    compressed_size.wrapping_add(frame_header_size)
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressContinue(
    state: *const ZSTD_rust_compressContinueState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    frame: c_uint,
    last_frame_chunk: c_uint,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_continue_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            src_size,
            frame,
            last_frame_chunk,
        )
    }
}

type CompressEndTraceFn = unsafe extern "C" fn(*mut c_void, usize);

/// Explicit projection for the public end-of-frame orchestration.
///
/// Rust owns callback ordering, output offset/capacity accounting, and
/// pledged-size validation.  The continue state is projected explicitly and
/// the opaque callback context retains only the private trace operation in C;
/// Rust serializes the epilogue from explicit frame and checksum projections.
#[repr(C)]
pub struct ZSTD_rust_compressEndState {
    callback_context: *mut c_void,
    compress_continue_state: *const ZSTD_rust_compressContinueState,
    trace: CompressEndTraceFn,
    consumed_src_size: *const u64,
    pledged_src_size_plus_one: u64,
    content_size_flag: c_int,
    stage: *mut c_int,
    no_dict_id_flag: c_int,
    checksum_flag: c_int,
    format: c_int,
    window_log: c_uint,
    checksum_state: *const XXH64_state_t,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressEndState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_compressEndState, compress_continue_state) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressEndState, trace) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressEndState, consumed_src_size) == 3 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressEndState, pledged_src_size_plus_one) == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressEndState, content_size_flag)
            == 4 * size_of::<usize>() + size_of::<u64>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressEndState, stage) == 5 * size_of::<usize>() + size_of::<u64>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressEndState, no_dict_id_flag)
            == 6 * size_of::<usize>() + size_of::<u64>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressEndState, checksum_flag)
            == 6 * size_of::<usize>() + size_of::<u64>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressEndState, format)
            == 6 * size_of::<usize>() + size_of::<u64>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressEndState, window_log)
            == 6 * size_of::<usize>() + size_of::<u64>() + 3 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressEndState, checksum_state)
            == 6 * size_of::<usize>()
                + size_of::<u64>()
                + 3 * size_of::<c_int>()
                + size_of::<c_uint>()
    );
    assert!(
        size_of::<ZSTD_rust_compressEndState>() == if size_of::<usize>() == 8 { 80 } else { 48 }
    );
};

unsafe fn compress_end_body_with(
    state: &ZSTD_rust_compressEndState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if state.compress_continue_state.is_null()
        || state.consumed_src_size.is_null()
        || state.stage.is_null()
        || state.checksum_state.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    let c_size = unsafe {
        ZSTD_rust_compressContinue(
            state.compress_continue_state,
            dst,
            dst_capacity,
            src,
            src_size,
            1,
            1,
        )
    };
    if ERR_isError(c_size) {
        return c_size;
    }

    let checksum = if state.checksum_flag != 0 {
        unsafe { XXH64_digest(state.checksum_state) as u32 }
    } else {
        0
    };
    let end_result = unsafe {
        ZSTD_rust_writeEpilogue(
            dst.cast::<u8>().add(c_size).cast(),
            dst_capacity.wrapping_sub(c_size),
            state.stage,
            state.no_dict_id_flag,
            state.checksum_flag,
            state.content_size_flag,
            state.format,
            state.window_log,
            checksum,
        )
    };
    if ERR_isError(end_result) {
        return end_result;
    }

    debug_assert!(!(state.content_size_flag != 0 && state.pledged_src_size_plus_one == 0));
    if state.pledged_src_size_plus_one != 0
        && state.pledged_src_size_plus_one != unsafe { (*state.consumed_src_size).wrapping_add(1) }
    {
        return ERROR(ZstdErrorCode::SrcSizeWrong);
    }

    unsafe { (state.trace)(state.callback_context, end_result) };
    c_size.wrapping_add(end_result)
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressEnd(
    state: *const ZSTD_rust_compressEndState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe { compress_end_body_with(&*state, dst, dst_capacity, src, src_size) }
}

type Compress2ResetFn = unsafe extern "C" fn(*mut c_void) -> usize;
type Compress2SetBufferModesFn = unsafe extern "C" fn(*mut c_void, c_int, c_int);
type Compress2StreamEndFn = unsafe extern "C" fn(
    *mut c_void,
    *mut c_void,
    usize,
    *mut usize,
    *const c_void,
    usize,
    *mut usize,
) -> usize;

/// Explicit projection for the C fallback behind `ZSTD_compress2`.
///
/// Rust owns the reset/mode-switch/stream-call ordering and result policy.
/// The opaque callback context remains in C, where callbacks retain access to
/// the private `ZSTD_CCtx` layout and the simple-arguments stream adapter.
#[repr(C)]
pub struct ZSTD_rust_compress2State {
    callback_context: *mut c_void,
    reset_session: Compress2ResetFn,
    set_buffer_modes: Compress2SetBufferModesFn,
    compress_stream_end: Compress2StreamEndFn,
    original_in_buffer_mode: c_int,
    original_out_buffer_mode: c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compress2State, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_compress2State, reset_session) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compress2State, set_buffer_modes) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compress2State, compress_stream_end) == 3 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compress2State, original_in_buffer_mode) == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compress2State, original_out_buffer_mode)
            == 4 * size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        size_of::<ZSTD_rust_compress2State>() == 4 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
};

unsafe fn compress2_body_with(
    state: &ZSTD_rust_compress2State,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    let reset_result = unsafe { (state.reset_session)(state.callback_context) };
    unsafe {
        (state.set_buffer_modes)(state.callback_context, ZSTD_BM_STABLE, ZSTD_BM_STABLE);
    }

    let mut output_pos = 0;
    let mut input_pos = 0;
    let result = if ERR_isError(reset_result) {
        reset_result
    } else {
        unsafe {
            (state.compress_stream_end)(
                state.callback_context,
                dst,
                dst_capacity,
                &mut output_pos,
                src,
                src_size,
                &mut input_pos,
            )
        }
    };

    unsafe {
        (state.set_buffer_modes)(
            state.callback_context,
            state.original_in_buffer_mode,
            state.original_out_buffer_mode,
        );
    }

    if ERR_isError(result) {
        return result;
    }
    if result != 0 {
        debug_assert_eq!(output_pos, dst_capacity);
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }
    debug_assert_eq!(input_pos, src_size);
    output_pos
}

/// Drive the `ZSTD_compress2_c()` fallback without crossing the C context
/// layout.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compress2(
    state: *const ZSTD_rust_compress2State,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe { compress2_body_with(&*state, dst, dst_capacity, src, src_size) }
}

/// Explicit projection for `ZSTD_CCtx_setParametersUsingCCtxParams`.
///
/// Rust owns the stage and dictionary policy while the C-owned parameter
/// objects cross the ABI as pointers to the shared layout mirror.
#[repr(C)]
pub struct ZSTD_rust_setParametersUsingCCtxParamsState {
    requested_params: *mut ZSTD_CCtx_params,
    source_params: *const ZSTD_CCtx_params,
    stream_stage: c_int,
    cdict: *const c_void,
}

const _: () = {
    assert!(
        offset_of!(
            ZSTD_rust_setParametersUsingCCtxParamsState,
            requested_params
        ) == 0
    );
    assert!(
        offset_of!(ZSTD_rust_setParametersUsingCCtxParamsState, source_params)
            == size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_setParametersUsingCCtxParamsState, stream_stage)
            == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_setParametersUsingCCtxParamsState, cdict) == 3 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_setParametersUsingCCtxParamsState>() == 4 * size_of::<usize>());
};

/// Apply stored parameters through the C-owned context projection.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_setParametersUsingCCtxParams(
    state: *const ZSTD_rust_setParametersUsingCCtxParamsState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.stream_stage != ZSTD_CSTREAM_STAGE_INIT {
        return ERROR(ZstdErrorCode::StageWrong);
    }
    if !state.cdict.is_null() {
        return ERROR(ZstdErrorCode::StageWrong);
    }
    unsafe {
        *state.requested_params = *state.source_params;
    }
    0
}

/// Explicit projection for `ZSTD_CCtx_setParameter`.
///
/// Rust owns the stage authorization and accepted-parameter policy while the
/// C-owned context exposes only the fields whose side effects remain private.
#[repr(C)]
pub struct ZSTD_rust_setParameterState {
    requested_params: *mut ZSTD_CCtx_params,
    stream_stage: c_int,
    c_params_changed: *mut c_int,
    static_size: usize,
    rust_simple_compress2_max_block_size_set: *mut c_uint,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_setParameterState, requested_params) == 0);
    assert!(offset_of!(ZSTD_rust_setParameterState, stream_stage) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_setParameterState, c_params_changed) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_setParameterState, static_size) == 3 * size_of::<usize>());
    assert!(
        offset_of!(
            ZSTD_rust_setParameterState,
            rust_simple_compress2_max_block_size_set
        ) == 4 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_setParameterState>() == 5 * size_of::<usize>());
};

#[inline]
fn set_parameter_is_supported(param: c_int) -> bool {
    matches!(
        param,
        ZSTD_C_COMPRESSION_LEVEL
            | ZSTD_C_WINDOW_LOG
            | ZSTD_C_HASH_LOG
            | ZSTD_C_CHAIN_LOG
            | ZSTD_C_SEARCH_LOG
            | ZSTD_C_MIN_MATCH
            | ZSTD_C_TARGET_LENGTH
            | ZSTD_C_STRATEGY
            | ZSTD_C_LDM_HASH_RATE_LOG
            | ZSTD_C_FORMAT
            | ZSTD_C_CONTENT_SIZE_FLAG
            | ZSTD_C_CHECKSUM_FLAG
            | ZSTD_C_DICT_ID_FLAG
            | ZSTD_C_FORCE_MAX_WINDOW
            | ZSTD_C_FORCE_ATTACH_DICT
            | ZSTD_C_LITERAL_COMPRESSION_MODE
            | ZSTD_C_JOB_SIZE
            | ZSTD_C_OVERLAP_LOG
            | ZSTD_C_RSYNCABLE
            | ZSTD_C_ENABLE_DEDICATED_DICT_SEARCH
            | ZSTD_C_ENABLE_LDM
            | ZSTD_C_LDM_HASH_LOG
            | ZSTD_C_LDM_MIN_MATCH
            | ZSTD_C_LDM_BUCKET_SIZE_LOG
            | ZSTD_C_TARGET_C_BLOCK_SIZE
            | ZSTD_C_SRC_SIZE_HINT
            | ZSTD_C_STABLE_IN_BUFFER
            | ZSTD_C_STABLE_OUT_BUFFER
            | ZSTD_C_BLOCK_DELIMITERS
            | ZSTD_C_VALIDATE_SEQUENCES
            | ZSTD_C_SPLIT_AFTER_SEQUENCES
            | ZSTD_C_BLOCK_SPLITTER_LEVEL
            | ZSTD_C_USE_ROW_MATCH_FINDER
            | ZSTD_C_DETERMINISTIC_REF_PREFIX
            | ZSTD_C_PREFETCH_CDICT_TABLES
            | ZSTD_C_ENABLE_SEQ_PRODUCER_FALLBACK
            | ZSTD_C_MAX_BLOCK_SIZE
            | ZSTD_C_REPCODE_RESOLUTION
    )
}

/// Apply one context parameter through the C-owned parameter object.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_setParameter(
    state: *const ZSTD_rust_setParameterState,
    param: c_int,
    value: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };

    if state.stream_stage != ZSTD_CSTREAM_STAGE_INIT {
        if ZSTD_rust_isUpdateAuthorized(param) == 0 {
            return ERROR(ZstdErrorCode::StageWrong);
        }
        unsafe {
            *state.c_params_changed = 1;
        }
    }
    if param == ZSTD_C_NB_WORKERS {
        if value != 0 && state.static_size != 0 {
            return ERROR(ZstdErrorCode::ParameterUnsupported);
        }
    } else if !set_parameter_is_supported(param) {
        return ERROR(ZstdErrorCode::ParameterUnsupported);
    }

    let result = unsafe { ZSTD_CCtxParams_setParameter(state.requested_params, param, value) };
    if !ERR_isError(result) && param == ZSTD_C_MAX_BLOCK_SIZE {
        unsafe {
            *state.rust_simple_compress2_max_block_size_set = 1;
        }
    }
    result
}

/// Explicit projection for `ZSTD_CCtx_refThreadPool`.
///
/// Rust owns the init-stage check and assignment policy while the pool slot
/// itself remains storage owned by the C context.  The pool value is opaque to
/// Rust because its private `POOL_ctx_s` layout is not part of this bridge.
#[repr(C)]
pub struct ZSTD_rust_refThreadPoolState {
    pool: *mut *mut c_void,
    requested_pool: *mut c_void,
    stream_stage: c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_refThreadPoolState, pool) == 0);
    assert!(offset_of!(ZSTD_rust_refThreadPoolState, requested_pool) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_refThreadPoolState, stream_stage) == 2 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_refThreadPoolState>() == 3 * size_of::<usize>());
};

/// Attach an opaque thread pool through the C-owned context slot.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_refThreadPool(
    state: *const ZSTD_rust_refThreadPoolState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.stream_stage != ZSTD_CSTREAM_STAGE_INIT {
        return ERROR(ZstdErrorCode::StageWrong);
    }
    unsafe {
        *state.pool = state.requested_pool;
    }
    0
}

type InitCCtxCallbackFn = unsafe extern "C" fn(*mut c_void);
type InitCCtxSetCustomMemFn = unsafe extern "C" fn(*mut c_void, *const c_void);
type InitCCtxResetFn = unsafe extern "C" fn(*mut c_void) -> usize;

/// Explicit projection for private heap-CCtx initialization.
///
/// Rust owns the initialization ordering while C retains the private context
/// layout, allocator publication, CPU-feature query, and reset operation
/// behind callbacks.
#[repr(C)]
pub struct ZSTD_rust_initCCtxState {
    callback_context: *mut c_void,
    custom_mem: *const c_void,
    zero: InitCCtxCallbackFn,
    set_custom_mem: InitCCtxSetCustomMemFn,
    set_bmi2: InitCCtxCallbackFn,
    reset: InitCCtxResetFn,
}

const _: () = {
    assert!(size_of::<InitCCtxCallbackFn>() == size_of::<usize>());
    assert!(size_of::<InitCCtxSetCustomMemFn>() == size_of::<usize>());
    assert!(size_of::<InitCCtxResetFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCCtxState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_initCCtxState, custom_mem) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCCtxState, zero) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCCtxState, set_custom_mem) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCCtxState, set_bmi2) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCCtxState, reset) == 5 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_initCCtxState>() == 6 * size_of::<usize>());
};

/// Initialize a heap-owned C compression context in the original order.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_initCCtx(state: *const ZSTD_rust_initCCtxState) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.callback_context.is_null() || state.custom_mem.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    unsafe {
        (state.zero)(state.callback_context);
        (state.set_custom_mem)(state.callback_context, state.custom_mem);
        (state.set_bmi2)(state.callback_context);
        let result = (state.reset)(state.callback_context);
        if ERR_isError(result) {
            return result;
        }
    }
    0
}

type CreateCCtxValidateCustomMemFn = unsafe extern "C" fn(*mut c_void) -> c_int;
type CreateCCtxAllocateFn = unsafe extern "C" fn(*mut c_void, usize) -> *mut c_void;
type CreateCCtxInitFn = unsafe extern "C" fn(*mut c_void, *mut c_void);

/// Explicit projection for the public `ZSTD_createCCtx_advanced` wrapper.
///
/// Rust owns custom-memory validation, allocation failure, and
/// allocate-before-init ordering. C retains private `ZSTD_CCtx` initialization
/// behind the final callback.
#[repr(C)]
pub struct ZSTD_rust_createCCtxState {
    callback_context: *mut c_void,
    cctx_size: usize,
    validate_custom_mem: CreateCCtxValidateCustomMemFn,
    allocate: CreateCCtxAllocateFn,
    init: CreateCCtxInitFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_createCCtxState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_createCCtxState, cctx_size) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_createCCtxState, validate_custom_mem) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_createCCtxState, allocate) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_createCCtxState, init) == 4 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_createCCtxState>() == size_of::<[usize; 5]>());
};

/// Allocate and initialize a C-owned compression context.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_createCCtx(
    state: *const ZSTD_rust_createCCtxState,
) -> *mut c_void {
    if state.is_null() {
        return ptr::null_mut();
    }
    let state = unsafe { &*state };
    if state.callback_context.is_null()
        || unsafe { (state.validate_custom_mem)(state.callback_context) == 0 }
    {
        return ptr::null_mut();
    }
    let cctx = unsafe { (state.allocate)(state.callback_context, state.cctx_size) };
    if cctx.is_null() {
        return ptr::null_mut();
    }
    unsafe { (state.init)(state.callback_context, cctx) };
    cctx
}

type CreateCDictAdvancedWrapperInitParamsFn = unsafe extern "C" fn(
    *mut c_void,
    *mut c_void,
    *const ZSTD_compressionParameters,
    *const c_void,
    usize,
    c_int,
);
type CreateCDictAdvancedWrapperCreateFn = unsafe extern "C" fn(
    *mut c_void,
    *const c_void,
    usize,
    c_int,
    c_int,
    *const c_void,
    *const c_void,
) -> *mut c_void;

/// Explicit projection for the public heap-CDict wrapper.
///
/// Rust owns the wrapper's preparation-to-construction ordering and forwards
/// the dictionary scalars. C retains the private `ZSTD_CCtx_params` setup and
/// the advanced-CDict implementation behind callbacks; allocation and
/// workspace ownership stay in the existing advanced2 path.
#[repr(C)]
pub struct ZSTD_rust_createCDictAdvancedWrapperState {
    callback_context: *mut c_void,
    cctx_params: *mut c_void,
    c_params: *const ZSTD_compressionParameters,
    custom_mem: *const c_void,
    init_params: CreateCDictAdvancedWrapperInitParamsFn,
    create: CreateCDictAdvancedWrapperCreateFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_createCDictAdvancedWrapperState, callback_context) == 0);
    assert!(
        offset_of!(ZSTD_rust_createCDictAdvancedWrapperState, cctx_params) == size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_createCDictAdvancedWrapperState, c_params) == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_createCDictAdvancedWrapperState, custom_mem) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_createCDictAdvancedWrapperState, init_params)
            == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_createCDictAdvancedWrapperState, create) == 5 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_createCDictAdvancedWrapperState>() == size_of::<[usize; 6]>());
};

/// Prepare a heap-CDict parameter object, then enter the existing advanced
/// construction path in the original callback order.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_createCDictAdvancedWrapper(
    state: *const ZSTD_rust_createCDictAdvancedWrapperState,
    dict: *const c_void,
    dict_size: usize,
    dict_load_method: c_int,
    dict_content_type: c_int,
) -> *mut c_void {
    if state.is_null() {
        return ptr::null_mut();
    }
    let state = unsafe { &*state };
    if state.cctx_params.is_null() || state.c_params.is_null() || state.custom_mem.is_null() {
        return ptr::null_mut();
    }

    unsafe {
        (state.init_params)(
            state.callback_context,
            state.cctx_params,
            state.c_params,
            state.custom_mem,
            dict_size,
            dict_content_type,
        );
        (state.create)(
            state.callback_context,
            dict,
            dict_size,
            dict_load_method,
            dict_content_type,
            state.cctx_params,
            state.custom_mem,
        )
    }
}

type InitStaticCCtxFn = unsafe extern "C" fn(*mut c_void) -> *mut c_void;
const ZSTD_STATIC_WORKSPACE_ALIGNMENT: usize = 8;

/// Explicit projection for the public `ZSTD_initStaticCCtx` wrapper.
///
/// Rust owns workspace pointer/alignment validation, minimum-size validation,
/// and callback ordering. C retains the private static-workspace layout and
/// context initialization behind one callback.
#[repr(C)]
pub struct ZSTD_rust_initStaticCCtxState {
    callback_context: *mut c_void,
    workspace: *mut c_void,
    workspace_size: usize,
    cctx_size: usize,
    init: InitStaticCCtxFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_initStaticCCtxState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_initStaticCCtxState, workspace) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initStaticCCtxState, workspace_size) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initStaticCCtxState, cctx_size) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initStaticCCtxState, init) == 4 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_initStaticCCtxState>() == size_of::<[usize; 5]>());
};

/// Validate static CCtx workspace ownership before entering the C leaf.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_initStaticCCtx(
    state: *const ZSTD_rust_initStaticCCtxState,
) -> *mut c_void {
    if state.is_null() {
        return ptr::null_mut();
    }
    let state = unsafe { &*state };
    if state.callback_context.is_null()
        || state.workspace.is_null()
        || (state.workspace as usize) & (ZSTD_STATIC_WORKSPACE_ALIGNMENT - 1) != 0
        || state.workspace_size <= state.cctx_size
    {
        return ptr::null_mut();
    }
    unsafe { (state.init)(state.callback_context) }
}

type FreeCCtxContentFn = unsafe extern "C" fn(*mut c_void);
type FreeCCtxObjectFn = unsafe extern "C" fn(*mut c_void);

/// Explicit projection for the public `ZSTD_freeCCtx` wrapper.
///
/// Rust owns the null/static/embedded-object policy and callback ordering.
/// C retains the private content teardown and custom allocator callbacks.
#[repr(C)]
pub struct ZSTD_rust_freeCCtxState {
    callback_context: *mut c_void,
    static_size: usize,
    cctx_in_workspace: c_int,
    free_content: FreeCCtxContentFn,
    free_object: FreeCCtxObjectFn,
}

const _: () = {
    assert!(size_of::<FreeCCtxContentFn>() == size_of::<usize>());
    assert!(size_of::<FreeCCtxObjectFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_freeCCtxState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_freeCCtxState, static_size) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_freeCCtxState, cctx_in_workspace) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_freeCCtxState, free_content) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_freeCCtxState, free_object) == 4 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_freeCCtxState>() == 5 * size_of::<usize>());
};

/// Free the C-owned context content and, when applicable, its outer object.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_freeCCtx(state: *const ZSTD_rust_freeCCtxState) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.callback_context.is_null() {
        return 0;
    }
    if state.static_size != 0 {
        return ERROR(ZstdErrorCode::MemoryAllocation);
    }
    unsafe {
        (state.free_content)(state.callback_context);
        if state.cctx_in_workspace == 0 {
            (state.free_object)(state.callback_context);
        }
    }
    0
}

type ClearAllDictsCallbackFn = unsafe extern "C" fn(*mut c_void);

/// Compose the dictionary teardown operations while leaving the private
/// ZSTD_CCtx fields behind C callbacks.
#[repr(C)]
pub struct ZSTD_rust_clearAllDictsState {
    callback_context: *mut c_void,
    free_local_dict_buffer: ClearAllDictsCallbackFn,
    free_local_cdict: ClearAllDictsCallbackFn,
    clear_local_dict: ClearAllDictsCallbackFn,
    clear_prefix_dict: ClearAllDictsCallbackFn,
    clear_cdict: ClearAllDictsCallbackFn,
}

const _: () = {
    assert!(size_of::<ClearAllDictsCallbackFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_clearAllDictsState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_clearAllDictsState, free_local_dict_buffer) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_clearAllDictsState, free_local_cdict) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_clearAllDictsState, clear_local_dict) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_clearAllDictsState, clear_prefix_dict) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_clearAllDictsState, clear_cdict) == 5 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_clearAllDictsState>() == 6 * size_of::<usize>());
};

/// Preserve the original local-dictionary, prefix-dictionary, and attached
/// CDict teardown order while keeping their private storage C-owned.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_clearAllDicts(state: *const ZSTD_rust_clearAllDictsState) {
    if state.is_null() {
        return;
    }
    let state = unsafe { &*state };
    if state.callback_context.is_null() {
        return;
    }
    unsafe {
        (state.free_local_dict_buffer)(state.callback_context);
        (state.free_local_cdict)(state.callback_context);
        (state.clear_local_dict)(state.callback_context);
        (state.clear_prefix_dict)(state.callback_context);
        (state.clear_cdict)(state.callback_context);
    }
}

type ResetCCtxClearAllDictsFn = unsafe extern "C" fn(*mut c_void);
type ResetCCtxResetParamsFn = unsafe extern "C" fn(*mut c_void) -> usize;

/// Explicit projection for the public `ZSTD_CCtx_reset` wrapper.
///
/// Rust owns the reset-directive policy and ordering. The callback context
/// remains in C, where the dictionary and parameter reset operations retain
/// access to the private `ZSTD_CCtx` layout.
#[repr(C)]
pub struct ZSTD_rust_resetCCtxState {
    callback_context: *mut c_void,
    rust_simple_compress2_completed: *mut c_uint,
    stream_stage: *mut c_int,
    pledged_src_size_plus_one: *mut u64,
    rust_simple_compress2_max_block_size_set: *mut c_uint,
    clear_all_dicts: ResetCCtxClearAllDictsFn,
    reset_params: ResetCCtxResetParamsFn,
}

const _: () = {
    assert!(size_of::<ResetCCtxClearAllDictsFn>() == size_of::<usize>());
    assert!(size_of::<ResetCCtxResetParamsFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetCCtxState, callback_context) == 0);
    assert!(
        offset_of!(ZSTD_rust_resetCCtxState, rust_simple_compress2_completed) == size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_resetCCtxState, stream_stage) == 2 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_resetCCtxState, pledged_src_size_plus_one) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_resetCCtxState,
            rust_simple_compress2_max_block_size_set
        ) == 4 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_resetCCtxState, clear_all_dicts) == 5 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetCCtxState, reset_params) == 6 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_resetCCtxState>() == 7 * size_of::<usize>());
};

/// Drive the public `ZSTD_CCtx_reset` policy through C-owned callbacks.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_resetCCtx(
    state: *const ZSTD_rust_resetCCtxState,
    reset: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };

    unsafe {
        *state.rust_simple_compress2_completed = 0;
    }
    if reset == ZSTD_RESET_SESSION_ONLY || reset == ZSTD_RESET_SESSION_AND_PARAMETERS {
        unsafe {
            *state.stream_stage = ZSTD_CSTREAM_STAGE_INIT;
            *state.pledged_src_size_plus_one = 0;
        }
    }
    if reset == ZSTD_RESET_PARAMETERS || reset == ZSTD_RESET_SESSION_AND_PARAMETERS {
        if unsafe { *state.stream_stage } != ZSTD_CSTREAM_STAGE_INIT {
            return ERROR(ZstdErrorCode::StageWrong);
        }
        unsafe { (state.clear_all_dicts)(state.callback_context) };
        unsafe {
            *state.rust_simple_compress2_max_block_size_set = 0;
        }
        return unsafe { (state.reset_params)(state.callback_context) };
    }
    0
}

type CopyCCtxInternalFn = unsafe extern "C" fn(
    *mut c_void,
    *const c_void,
    *const ZSTD_frameParameters,
    u64,
    c_int,
) -> usize;

/// Explicit projection for the public `ZSTD_copyCCtx` wrapper.
///
/// Rust owns zero-to-unknown pledged-size normalization and frame-parameter
/// construction. C retains the private table and workspace copy operation.
#[repr(C)]
pub struct ZSTD_rust_copyCCtxState {
    callback_context: *mut c_void,
    src_cctx: *const c_void,
    f_params: *const ZSTD_frameParameters,
    pledged_src_size: *const u64,
    zbuff: *const c_int,
    copy_internal: Option<CopyCCtxInternalFn>,
}

const _: () = {
    assert!(size_of::<CopyCCtxInternalFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyCCtxState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_copyCCtxState, src_cctx) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyCCtxState, f_params) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyCCtxState, pledged_src_size) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyCCtxState, zbuff) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyCCtxState, copy_internal) == 5 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_copyCCtxState>() == size_of::<[usize; 6]>());
};

/// Normalize the public copy request before invoking the private C operation.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_copyCCtx(state: *const ZSTD_rust_copyCCtxState) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let Some(copy_internal) = state.copy_internal else {
        return ERROR(ZstdErrorCode::Generic);
    };
    if state.callback_context.is_null()
        || state.src_cctx.is_null()
        || state.f_params.is_null()
        || state.pledged_src_size.is_null()
        || state.zbuff.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    let pledged_src_size = unsafe { *state.pledged_src_size };
    let pledged_src_size = if pledged_src_size == 0 {
        ZSTD_CONTENTSIZE_UNKNOWN
    } else {
        pledged_src_size
    };
    let mut f_params = unsafe { *state.f_params };
    f_params.contentSizeFlag = c_int::from(pledged_src_size != ZSTD_CONTENTSIZE_UNKNOWN);
    unsafe {
        copy_internal(
            state.callback_context,
            state.src_cctx,
            &f_params,
            pledged_src_size,
            *state.zbuff,
        )
    }
}

type CopyCCtxResetFn = unsafe extern "C" fn(
    *mut c_void,
    *const c_void,
    *const ZSTD_frameParameters,
    u64,
    c_int,
) -> usize;
type CopyCCtxMarkTablesFn = unsafe extern "C" fn(*mut c_void);

#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
struct ZSTD_rust_copyWindowState {
    next_src: *const c_void,
    base: *const c_void,
    dict_base: *const c_void,
    dict_limit: c_uint,
    low_limit: c_uint,
    nb_overflow_corrections: c_uint,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_copyWindowState, next_src) == 0);
    assert!(offset_of!(ZSTD_rust_copyWindowState, base) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyWindowState, dict_base) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyWindowState, dict_limit) == 3 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_copyWindowState, low_limit)
            == 3 * size_of::<usize>() + size_of::<c_uint>()
    );
    assert!(
        offset_of!(ZSTD_rust_copyWindowState, nb_overflow_corrections)
            == 3 * size_of::<usize>() + 2 * size_of::<c_uint>()
    );
    assert!(
        size_of::<ZSTD_rust_copyWindowState>()
            == (3 * size_of::<usize>() + 3 * size_of::<c_uint>()).div_ceil(size_of::<usize>())
                * size_of::<usize>()
    );
};

const _: () = {
    assert!(size_of::<ZSTD_customMem>() == 3 * size_of::<usize>());
};

/// Projection for the private `ZSTD_copyCCtx_internal` operation.
///
/// Rust owns the stage/error branch and the order of the reset, workspace,
/// table, window, dictionary, and block-state operations. C retains access to
/// the private `ZSTD_CCtx` layout behind callbacks.
#[repr(C)]
pub struct ZSTD_rust_copyCCtxInternalState {
    callback_context: *mut c_void,
    src_cctx: *const c_void,
    f_params: *const ZSTD_frameParameters,
    pledged_src_size: u64,
    source_stage: *const c_int,
    destination_custom_mem: *mut c_void,
    source_custom_mem: *const c_void,
    reset: Option<CopyCCtxResetFn>,
    mark_tables_dirty: Option<CopyCCtxMarkTablesFn>,
    mark_tables_clean: Option<CopyCCtxMarkTablesFn>,
    destination_hash_table: *mut *mut c_uint,
    source_hash_table: *const c_uint,
    source_hash_log: *const c_uint,
    destination_chain_table: *mut *mut c_uint,
    source_chain_table: *const c_uint,
    source_chain_log: *const c_uint,
    destination_hash_table3: *mut *mut c_uint,
    source_hash_table3: *const c_uint,
    source_hash_log3: *const c_uint,
    source_strategy: *const c_int,
    source_use_row_match_finder: *const c_int,
    destination_window: *mut c_void,
    source_window: *const c_void,
    destination_next_to_update: *mut c_uint,
    source_next_to_update: *const c_uint,
    destination_loaded_dict_end: *mut c_uint,
    source_loaded_dict_end: *const c_uint,
    destination_dict_id: *mut c_uint,
    source_dict_id: *const c_uint,
    destination_dict_content_size: *mut usize,
    source_dict_content_size: *const usize,
    destination_block_state: *mut *mut ZSTD_compressedBlockState_t,
    source_block_state: *const ZSTD_compressedBlockState_t,
    zbuff: c_int,
}

const _: () = {
    assert!(size_of::<CopyCCtxResetFn>() == size_of::<usize>());
    assert!(size_of::<CopyCCtxMarkTablesFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyCCtxInternalState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_copyCCtxInternalState, src_cctx) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_copyCCtxInternalState, f_params) == 2 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_copyCCtxInternalState, pledged_src_size) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_copyCCtxInternalState, source_stage)
            == 3 * size_of::<usize>() + size_of::<u64>()
    );
    assert!(
        offset_of!(ZSTD_rust_copyCCtxInternalState, zbuff)
            == 3 * size_of::<usize>() + size_of::<u64>() + 29 * size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_copyCCtxInternalState>()
            == (offset_of!(ZSTD_rust_copyCCtxInternalState, zbuff) + size_of::<c_int>())
                .div_ceil(size_of::<usize>())
                * size_of::<usize>()
    );
};

/// Run the private context-copy operation through C-owned layout callbacks
/// and copy the compressed-block state directly in Rust.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_copyCCtxInternal(
    state: *const ZSTD_rust_copyCCtxInternalState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let (Some(reset), Some(mark_tables_dirty), Some(mark_tables_clean)) = (
        state.reset,
        state.mark_tables_dirty,
        state.mark_tables_clean,
    ) else {
        return ERROR(ZstdErrorCode::Generic);
    };
    if state.callback_context.is_null()
        || state.src_cctx.is_null()
        || state.f_params.is_null()
        || state.source_stage.is_null()
        || state.destination_custom_mem.is_null()
        || state.source_custom_mem.is_null()
        || state.destination_hash_table.is_null()
        || state.destination_chain_table.is_null()
        || state.destination_hash_table3.is_null()
        || state.source_hash_log.is_null()
        || state.source_chain_log.is_null()
        || state.source_hash_log3.is_null()
        || state.source_strategy.is_null()
        || state.source_use_row_match_finder.is_null()
        || state.destination_window.is_null()
        || state.source_window.is_null()
        || state.destination_next_to_update.is_null()
        || state.source_next_to_update.is_null()
        || state.destination_loaded_dict_end.is_null()
        || state.source_loaded_dict_end.is_null()
        || state.destination_dict_id.is_null()
        || state.source_dict_id.is_null()
        || state.destination_dict_content_size.is_null()
        || state.source_dict_content_size.is_null()
        || state.destination_block_state.is_null()
        || state.source_block_state.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    if unsafe { *state.source_stage } != ZSTD_COMPRESSION_STAGE_INIT {
        return ERROR(ZstdErrorCode::StageWrong);
    }

    let source_hash_log = unsafe { *state.source_hash_log };
    let source_chain_log = unsafe { *state.source_chain_log };
    let source_hash_log3 = unsafe { *state.source_hash_log3 };
    let source_strategy = unsafe { *state.source_strategy };
    let source_use_row_match_finder = unsafe { *state.source_use_row_match_finder };
    let Some(hash_table_size) = 1usize.checked_shl(source_hash_log) else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let chain_table_size = if ZSTD_rust_params_allocateChainTable(
        source_strategy,
        source_use_row_match_finder,
        0,
    ) != 0
    {
        let Some(size) = 1usize.checked_shl(source_chain_log) else {
            return ERROR(ZstdErrorCode::Generic);
        };
        size
    } else {
        0
    };
    let hash_table3_size = if source_hash_log3 != 0 {
        let Some(size) = 1usize.checked_shl(source_hash_log3) else {
            return ERROR(ZstdErrorCode::Generic);
        };
        size
    } else {
        0
    };

    unsafe {
        ptr::copy(
            state.source_custom_mem.cast::<ZSTD_customMem>(),
            state.destination_custom_mem.cast::<ZSTD_customMem>(),
            1,
        );
        let reset_error = reset(
            state.callback_context,
            state.src_cctx,
            state.f_params,
            state.pledged_src_size,
            state.zbuff,
        );
        if ERR_isError(reset_error) {
            return reset_error;
        }
        let destination_hash_table = *state.destination_hash_table;
        let destination_chain_table = *state.destination_chain_table;
        let destination_hash_table3 = *state.destination_hash_table3;
        if (hash_table_size != 0
            && (destination_hash_table.is_null() || state.source_hash_table.is_null()))
            || (chain_table_size != 0
                && (destination_chain_table.is_null() || state.source_chain_table.is_null()))
            || (hash_table3_size != 0
                && (destination_hash_table3.is_null() || state.source_hash_table3.is_null()))
        {
            return ERROR(ZstdErrorCode::Generic);
        }
        mark_tables_dirty(state.callback_context);
        if hash_table_size != 0 {
            ptr::copy_nonoverlapping(
                state.source_hash_table,
                destination_hash_table,
                hash_table_size,
            );
        }
        if chain_table_size != 0 {
            ptr::copy_nonoverlapping(
                state.source_chain_table,
                destination_chain_table,
                chain_table_size,
            );
        }
        if hash_table3_size != 0 {
            ptr::copy_nonoverlapping(
                state.source_hash_table3,
                destination_hash_table3,
                hash_table3_size,
            );
        }
        mark_tables_clean(state.callback_context);
        ptr::copy(
            state.source_window.cast::<ZSTD_rust_copyWindowState>(),
            state.destination_window.cast::<ZSTD_rust_copyWindowState>(),
            1,
        );
        *state.destination_next_to_update = *state.source_next_to_update;
        *state.destination_loaded_dict_end = *state.source_loaded_dict_end;
        *state.destination_dict_id = *state.source_dict_id;
        *state.destination_dict_content_size = *state.source_dict_content_size;
        let destination_block_state = *state.destination_block_state;
        if destination_block_state.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        ptr::copy_nonoverlapping(state.source_block_state, destination_block_state, 1);
    }
    0
}

type CompressAdvancedInitParamsFn = unsafe extern "C" fn(*mut c_void, *const ZSTD_parameters);
type CompressAdvancedInternalFn = unsafe extern "C" fn(
    *mut c_void,
    *mut c_void,
    usize,
    *const c_void,
    usize,
    *const c_void,
    usize,
) -> usize;

/// Explicit projection for the public `ZSTD_compress_advanced` wrapper.
///
/// Rust owns parameter validation and the init-then-compress order. C retains
/// the private `simpleApiParams` initialization and advanced compression call.
#[repr(C)]
pub struct ZSTD_rust_compressAdvancedState {
    callback_context: *mut c_void,
    init_params: Option<CompressAdvancedInitParamsFn>,
    compress_internal: Option<CompressAdvancedInternalFn>,
}

const _: () = {
    assert!(size_of::<CompressAdvancedInitParamsFn>() == size_of::<usize>());
    assert!(size_of::<CompressAdvancedInternalFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressAdvancedState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_compressAdvancedState, init_params) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressAdvancedState, compress_internal) == 2 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_compressAdvancedState>() == size_of::<[usize; 3]>());
};

/// Validate parameters and invoke the C-owned advanced compression operation.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressAdvanced(
    state: *const ZSTD_rust_compressAdvancedState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    dict: *const c_void,
    dict_size: usize,
    params: *const ZSTD_parameters,
) -> usize {
    if state.is_null() || params.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let Some(init_params) = state.init_params else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(compress_internal) = state.compress_internal else {
        return ERROR(ZstdErrorCode::Generic);
    };
    if state.callback_context.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let params = unsafe { &*params };
    let check_result = ZSTD_rust_params_checkCParams(params.cParams);
    if ERR_isError(check_result) {
        return check_result;
    }
    unsafe { init_params(state.callback_context, params) };
    unsafe {
        compress_internal(
            state.callback_context,
            dst,
            dst_capacity,
            src,
            src_size,
            dict,
            dict_size,
        )
    }
}

type CompressBeginAdvancedInitParamsFn = unsafe extern "C" fn(*mut c_void, *const ZSTD_parameters);
type CompressBeginAdvancedBeginFn =
    unsafe extern "C" fn(*mut c_void, *const c_void, usize, *const c_void, u64) -> usize;

/// Explicit projection for the public `ZSTD_compressBegin_advanced` wrapper.
///
/// Rust owns public parameter validation and init-then-begin ordering. C
/// retains private `ZSTD_CCtx_params` initialization and the final begin
/// operation behind callbacks.
#[repr(C)]
pub struct ZSTD_rust_compressBeginAdvancedState {
    cctx: *mut c_void,
    cctx_params: *mut c_void,
    init_params: CompressBeginAdvancedInitParamsFn,
    begin: CompressBeginAdvancedBeginFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressBeginAdvancedState, cctx) == 0);
    assert!(offset_of!(ZSTD_rust_compressBeginAdvancedState, cctx_params) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressBeginAdvancedState, init_params) == 2 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_compressBeginAdvancedState, begin) == 3 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_compressBeginAdvancedState>() == size_of::<[usize; 4]>());
};

/// Validate parameters and begin a frame through the C-owned operation.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressBeginAdvanced(
    state: *const ZSTD_rust_compressBeginAdvancedState,
    dict: *const c_void,
    dict_size: usize,
    params: *const ZSTD_parameters,
    pledged_src_size: u64,
) -> usize {
    if state.is_null() || params.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.cctx.is_null() || state.cctx_params.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let params = unsafe { &*params };
    let check_result = ZSTD_rust_params_checkCParams(params.cParams);
    if ERR_isError(check_result) {
        return check_result;
    }
    unsafe {
        (state.init_params)(state.cctx_params, params);
        (state.begin)(
            state.cctx,
            dict,
            dict_size,
            state.cctx_params,
            pledged_src_size,
        )
    }
}

type CompressUsingDictInitParamsFn =
    unsafe extern "C" fn(*mut c_void, *const ZSTD_parameters, c_int);

/// Explicit projection for the public `ZSTD_compress_usingDict` wrapper.
///
/// Rust owns compression-parameter selection, dictionary-presence handling,
/// and the default-level normalization. C retains the private
/// `ZSTD_CCtx_params` initialization and advanced compression operation.
#[repr(C)]
pub struct ZSTD_rust_compressUsingDictState {
    callback_context: *mut c_void,
    exclusion_mask: *const c_uint,
    init_params: Option<CompressUsingDictInitParamsFn>,
    compress_internal: Option<CompressAdvancedInternalFn>,
}

const _: () = {
    assert!(size_of::<CompressUsingDictInitParamsFn>() == size_of::<usize>());
    assert!(size_of::<CompressAdvancedInternalFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressUsingDictState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_compressUsingDictState, exclusion_mask) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressUsingDictState, init_params) == 2 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressUsingDictState, compress_internal) == 3 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_compressUsingDictState>() == size_of::<[usize; 4]>());
};

/// Select parameters and invoke the C-owned dictionary compression operation.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressUsingDict(
    state: *const ZSTD_rust_compressUsingDictState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    dict: *const c_void,
    dict_size: usize,
    compression_level: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let Some(init_params) = state.init_params else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(compress_internal) = state.compress_internal else {
        return ERROR(ZstdErrorCode::Generic);
    };
    if state.callback_context.is_null() || state.exclusion_mask.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let dict_size_for_params = if dict.is_null() { 0 } else { dict_size };
    let params = ZSTD_rust_params_getParamsInternal(
        compression_level,
        src_size as u64,
        dict_size_for_params,
        ZSTD_RUST_CPM_NO_ATTACH_DICT,
        unsafe { *state.exclusion_mask },
    );
    let init_level = if compression_level == 0 {
        ZSTD_rust_params_defaultCLevel()
    } else {
        compression_level
    };
    unsafe { init_params(state.callback_context, &params, init_level) };
    unsafe {
        compress_internal(
            state.callback_context,
            dst,
            dst_capacity,
            src,
            src_size,
            dict,
            dict_size,
        )
    }
}

type ResetCStreamResetFn = unsafe extern "C" fn(*mut c_void) -> usize;
type ResetCStreamSetPledgedSrcSizeFn = unsafe extern "C" fn(*mut c_void, u64) -> usize;

/// Explicit projection for the public `ZSTD_resetCStream` wrapper.
///
/// Rust owns the zero-to-unknown conversion, callback ordering, and error
/// propagation. The opaque callback context stays in C, where the callbacks
/// retain access to the private `ZSTD_CCtx` layout.
#[repr(C)]
pub struct ZSTD_rust_resetCStreamState {
    callback_context: *mut c_void,
    reset_session: ResetCStreamResetFn,
    set_pledged_src_size: ResetCStreamSetPledgedSrcSizeFn,
}

const _: () = {
    assert!(size_of::<ResetCStreamResetFn>() == size_of::<usize>());
    assert!(size_of::<ResetCStreamSetPledgedSrcSizeFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetCStreamState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_resetCStreamState, reset_session) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_resetCStreamState, set_pledged_src_size) == 2 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_resetCStreamState>() == 3 * size_of::<usize>());
};

/// Drive the public `ZSTD_resetCStream` policy through C-owned callbacks.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_resetCStream(
    state: *const ZSTD_rust_resetCStreamState,
    pss: u64,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let pledged_src_size = if pss == 0 {
        ZSTD_CONTENTSIZE_UNKNOWN
    } else {
        pss
    };

    let reset_result = unsafe { (state.reset_session)(state.callback_context) };
    if ERR_isError(reset_result) {
        return reset_result;
    }
    let pledged_size_result =
        unsafe { (state.set_pledged_src_size)(state.callback_context, pledged_src_size) };
    if ERR_isError(pledged_size_result) {
        return pledged_size_result;
    }
    0
}

type InitCStreamUsingCDictAdvancedResetFn = unsafe extern "C" fn(*mut c_void) -> usize;
type InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn =
    unsafe extern "C" fn(*mut c_void, u64) -> usize;
type InitCStreamUsingCDictAdvancedSetFrameParamsFn =
    unsafe extern "C" fn(*mut c_void, c_uint, c_uint, c_uint);
type InitCStreamUsingCDictAdvancedRefCDictFn =
    unsafe extern "C" fn(*mut c_void, *const c_void) -> usize;

/// Explicit projection for `ZSTD_initCStream_usingCDict_advanced`.
///
/// Rust owns the public wrapper's callback order and error propagation while
/// C retains the private context and dictionary/parameter mutations.
#[repr(C)]
pub struct ZSTD_rust_initCStreamUsingCDictAdvancedState {
    callback_context: *mut c_void,
    reset_session: InitCStreamUsingCDictAdvancedResetFn,
    set_pledged_src_size: InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn,
    set_frame_params: InitCStreamUsingCDictAdvancedSetFrameParamsFn,
    ref_cdict: InitCStreamUsingCDictAdvancedRefCDictFn,
}

const _: () = {
    assert!(size_of::<InitCStreamUsingCDictAdvancedResetFn>() == size_of::<usize>());
    assert!(size_of::<InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn>() == size_of::<usize>());
    assert!(size_of::<InitCStreamUsingCDictAdvancedSetFrameParamsFn>() == size_of::<usize>());
    assert!(size_of::<InitCStreamUsingCDictAdvancedRefCDictFn>() == size_of::<usize>());
    assert!(
        offset_of!(
            ZSTD_rust_initCStreamUsingCDictAdvancedState,
            callback_context
        ) == 0
    );
    assert!(
        offset_of!(ZSTD_rust_initCStreamUsingCDictAdvancedState, reset_session)
            == size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_initCStreamUsingCDictAdvancedState,
            set_pledged_src_size
        ) == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_initCStreamUsingCDictAdvancedState,
            set_frame_params
        ) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_initCStreamUsingCDictAdvancedState, ref_cdict)
            == 4 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_initCStreamUsingCDictAdvancedState>() == 5 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_initCStreamUsingCDictAdvanced(
    state: *const ZSTD_rust_initCStreamUsingCDictAdvancedState,
    pledged_src_size: u64,
    content_size_flag: c_uint,
    checksum_flag: c_uint,
    no_dict_id_flag: c_uint,
    cdict: *const c_void,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };

    let result = unsafe { (state.reset_session)(state.callback_context) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.set_pledged_src_size)(state.callback_context, pledged_src_size) };
    if ERR_isError(result) {
        return result;
    }
    unsafe {
        (state.set_frame_params)(
            state.callback_context,
            content_size_flag,
            checksum_flag,
            no_dict_id_flag,
        )
    };
    let result = unsafe { (state.ref_cdict)(state.callback_context, cdict) };
    if ERR_isError(result) {
        return result;
    }
    0
}

/// Explicit projection for `ZSTD_initCStream_usingCDict`.
#[repr(C)]
pub struct ZSTD_rust_initCStreamUsingCDictState {
    callback_context: *mut c_void,
    reset_session: InitCStreamUsingCDictAdvancedResetFn,
    ref_cdict: InitCStreamUsingCDictAdvancedRefCDictFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_initCStreamUsingCDictState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_initCStreamUsingCDictState, reset_session) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCStreamUsingCDictState, ref_cdict) == 2 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_initCStreamUsingCDictState>() == 3 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_initCStreamUsingCDict(
    state: *const ZSTD_rust_initCStreamUsingCDictState,
    cdict: *const c_void,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };

    let result = unsafe { (state.reset_session)(state.callback_context) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.ref_cdict)(state.callback_context, cdict) };
    if ERR_isError(result) {
        return result;
    }
    0
}

type InitCStreamSrcSizeSetLevelFn = unsafe extern "C" fn(*mut c_void, c_int) -> usize;

/// Explicit projection for `ZSTD_initCStream_srcSize`.
#[repr(C)]
pub struct ZSTD_rust_initCStreamSrcSizeState {
    callback_context: *mut c_void,
    reset_session: InitCStreamUsingCDictAdvancedResetFn,
    ref_cdict: InitCStreamUsingCDictAdvancedRefCDictFn,
    set_level: InitCStreamSrcSizeSetLevelFn,
    set_pledged_src_size: InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_initCStreamSrcSizeState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_initCStreamSrcSizeState, reset_session) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCStreamSrcSizeState, ref_cdict) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCStreamSrcSizeState, set_level) == 3 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_initCStreamSrcSizeState, set_pledged_src_size)
            == 4 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_initCStreamSrcSizeState>() == 5 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_initCStreamSrcSize(
    state: *const ZSTD_rust_initCStreamSrcSizeState,
    pss: u64,
    compression_level: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let pledged_src_size = if pss == 0 {
        ZSTD_CONTENTSIZE_UNKNOWN
    } else {
        pss
    };

    let result = unsafe { (state.reset_session)(state.callback_context) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.ref_cdict)(state.callback_context, ptr::null()) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.set_level)(state.callback_context, compression_level) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.set_pledged_src_size)(state.callback_context, pledged_src_size) };
    if ERR_isError(result) {
        return result;
    }
    0
}

/// Explicit projection for `ZSTD_initCStream`.
#[repr(C)]
pub struct ZSTD_rust_initCStreamState {
    callback_context: *mut c_void,
    reset_session: InitCStreamUsingCDictAdvancedResetFn,
    ref_cdict: InitCStreamUsingCDictAdvancedRefCDictFn,
    set_level: InitCStreamSrcSizeSetLevelFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_initCStreamState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_initCStreamState, reset_session) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCStreamState, ref_cdict) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCStreamState, set_level) == 3 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_initCStreamState>() == 4 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_initCStream(
    state: *const ZSTD_rust_initCStreamState,
    compression_level: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };

    let result = unsafe { (state.reset_session)(state.callback_context) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.ref_cdict)(state.callback_context, ptr::null()) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.set_level)(state.callback_context, compression_level) };
    if ERR_isError(result) {
        return result;
    }
    0
}

type InitCStreamUsingDictLoadDictionaryFn =
    unsafe extern "C" fn(*mut c_void, *const c_void, usize) -> usize;

/// Explicit projection for `ZSTD_initCStream_usingDict`.
#[repr(C)]
pub struct ZSTD_rust_initCStreamUsingDictState {
    callback_context: *mut c_void,
    reset_session: InitCStreamUsingCDictAdvancedResetFn,
    set_level: InitCStreamSrcSizeSetLevelFn,
    load_dictionary: InitCStreamUsingDictLoadDictionaryFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_initCStreamUsingDictState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_initCStreamUsingDictState, reset_session) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_initCStreamUsingDictState, set_level) == 2 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_initCStreamUsingDictState, load_dictionary) == 3 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_initCStreamUsingDictState>() == 4 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_initCStreamUsingDict(
    state: *const ZSTD_rust_initCStreamUsingDictState,
    dict: *const c_void,
    dict_size: usize,
    compression_level: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };

    let result = unsafe { (state.reset_session)(state.callback_context) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.set_level)(state.callback_context, compression_level) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.load_dictionary)(state.callback_context, dict, dict_size) };
    if ERR_isError(result) {
        return result;
    }
    0
}

type InitCStreamAdvancedCheckCParamsFn =
    unsafe extern "C" fn(*mut c_void, ZSTD_compressionParameters) -> usize;
type InitCStreamAdvancedSetZstdParamsFn = unsafe extern "C" fn(*mut c_void, *const ZSTD_parameters);

/// Explicit projection for `ZSTD_initCStream_advanced`.
#[repr(C)]
pub struct ZSTD_rust_initCStreamAdvancedState {
    callback_context: *mut c_void,
    reset_session: InitCStreamUsingCDictAdvancedResetFn,
    set_pledged_src_size: InitCStreamUsingCDictAdvancedSetPledgedSrcSizeFn,
    check_c_params: InitCStreamAdvancedCheckCParamsFn,
    set_zstd_params: InitCStreamAdvancedSetZstdParamsFn,
    load_dictionary: InitCStreamUsingDictLoadDictionaryFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_initCStreamAdvancedState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_initCStreamAdvancedState, reset_session) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_initCStreamAdvancedState, set_pledged_src_size)
            == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_initCStreamAdvancedState, check_c_params) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_initCStreamAdvancedState, set_zstd_params) == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_initCStreamAdvancedState, load_dictionary) == 5 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_initCStreamAdvancedState>() == 6 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_initCStreamAdvanced(
    state: *const ZSTD_rust_initCStreamAdvancedState,
    params: *const ZSTD_parameters,
    pss: u64,
    dict: *const c_void,
    dict_size: usize,
) -> usize {
    if state.is_null() || params.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let params = unsafe { &*params };
    let pledged_src_size = if pss == 0 && params.fParams.contentSizeFlag == 0 {
        ZSTD_CONTENTSIZE_UNKNOWN
    } else {
        pss
    };

    let result = unsafe { (state.reset_session)(state.callback_context) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.set_pledged_src_size)(state.callback_context, pledged_src_size) };
    if ERR_isError(result) {
        return result;
    }
    let result = unsafe { (state.check_c_params)(state.callback_context, params.cParams) };
    if ERR_isError(result) {
        return result;
    }
    unsafe { (state.set_zstd_params)(state.callback_context, params) };
    let result = unsafe { (state.load_dictionary)(state.callback_context, dict, dict_size) };
    if ERR_isError(result) {
        return result;
    }
    0
}

type SetCParamsCheckCParamsFn =
    unsafe extern "C" fn(*mut c_void, ZSTD_compressionParameters) -> usize;
type SetCParamsSetParameterFn = unsafe extern "C" fn(*mut c_void, c_int, c_int) -> usize;

/// Explicit projection for `ZSTD_CCtx_setCParams`.
#[repr(C)]
pub struct ZSTD_rust_setCParamsState {
    callback_context: *mut c_void,
    check_c_params: SetCParamsCheckCParamsFn,
    set_parameter: SetCParamsSetParameterFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_setCParamsState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_setCParamsState, check_c_params) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_setCParamsState, set_parameter) == 2 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_setCParamsState>() == 3 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_setCParams(
    state: *const ZSTD_rust_setCParamsState,
    cparams: ZSTD_compressionParameters,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let result = unsafe { (state.check_c_params)(state.callback_context, cparams) };
    if ERR_isError(result) {
        return result;
    }

    let parameters = [
        (ZSTD_C_WINDOW_LOG, cparams.windowLog as c_int),
        (ZSTD_C_CHAIN_LOG, cparams.chainLog as c_int),
        (ZSTD_C_HASH_LOG, cparams.hashLog as c_int),
        (ZSTD_C_SEARCH_LOG, cparams.searchLog as c_int),
        (ZSTD_C_MIN_MATCH, cparams.minMatch as c_int),
        (ZSTD_C_TARGET_LENGTH, cparams.targetLength as c_int),
        (ZSTD_C_STRATEGY, cparams.strategy),
    ];
    for (param, value) in parameters {
        let result = unsafe { (state.set_parameter)(state.callback_context, param, value) };
        if ERR_isError(result) {
            return result;
        }
    }
    0
}

type SetFParamsSetParameterFn = unsafe extern "C" fn(*mut c_void, c_int, c_int) -> usize;

/// Explicit projection for `ZSTD_CCtx_setFParams`.
#[repr(C)]
pub struct ZSTD_rust_setFParamsState {
    callback_context: *mut c_void,
    set_parameter: SetFParamsSetParameterFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_setFParamsState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_setFParamsState, set_parameter) == size_of::<usize>());
    assert!(size_of::<ZSTD_rust_setFParamsState>() == 2 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_setFParams(
    state: *const ZSTD_rust_setFParamsState,
    fparams: ZSTD_frameParameters,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let parameters = [
        (
            ZSTD_C_CONTENT_SIZE_FLAG,
            (fparams.contentSizeFlag != 0) as c_int,
        ),
        (ZSTD_C_CHECKSUM_FLAG, (fparams.checksumFlag != 0) as c_int),
        (ZSTD_C_DICT_ID_FLAG, (fparams.noDictIDFlag == 0) as c_int),
    ];
    for (param, value) in parameters {
        let result = unsafe { (state.set_parameter)(state.callback_context, param, value) };
        if ERR_isError(result) {
            return result;
        }
    }
    0
}

type SetParamsCheckCParamsFn =
    unsafe extern "C" fn(*mut c_void, ZSTD_compressionParameters) -> usize;
type SetParamsSetFParamsFn = unsafe extern "C" fn(*mut c_void, ZSTD_frameParameters) -> usize;
type SetParamsSetCParamsFn = unsafe extern "C" fn(*mut c_void, ZSTD_compressionParameters) -> usize;

/// Explicit projection for `ZSTD_CCtx_setParams`.
#[repr(C)]
pub struct ZSTD_rust_setParamsState {
    callback_context: *mut c_void,
    check_c_params: SetParamsCheckCParamsFn,
    set_f_params: SetParamsSetFParamsFn,
    set_c_params: SetParamsSetCParamsFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_setParamsState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_setParamsState, check_c_params) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_setParamsState, set_f_params) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_setParamsState, set_c_params) == 3 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_setParamsState>() == 4 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_setParams(
    state: *const ZSTD_rust_setParamsState,
    params: ZSTD_parameters,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };

    let result = unsafe { (state.check_c_params)(state.callback_context, params.cParams) };
    if ERR_isError(result) {
        return result;
    }

    let result = unsafe { (state.set_f_params)(state.callback_context, params.fParams) };
    if ERR_isError(result) {
        return result;
    }

    let result = unsafe { (state.set_c_params)(state.callback_context, params.cParams) };
    if ERR_isError(result) {
        return result;
    }
    0
}

type CompressStreamResetFn = unsafe extern "C" fn(*mut c_void) -> usize;

/// Explicit projection of the single-threaded `ZSTD_compressStream_generic`
/// state machine.
///
/// Rust owns buffering, output-drain policy, directive handling, and stream
/// stage transitions.  Continue/end state projections retain the migrated
/// frame construction path; the opaque callback context remains only for
/// session reset.
#[repr(C)]
pub struct ZSTD_rust_compressStreamState {
    callback_context: *mut c_void,
    in_buffer_mode: c_int,
    out_buffer_mode: c_int,
    stream_stage: *mut c_int,
    block_size_max: usize,
    stable_in_not_consumed: *mut usize,
    in_buff: *mut c_void,
    in_buff_size: usize,
    in_to_compress: *mut usize,
    in_buff_pos: *mut usize,
    in_buff_target: *mut usize,
    out_buff: *mut c_void,
    out_buff_size: usize,
    out_buff_content_size: *mut usize,
    out_buff_flushed_size: *mut usize,
    frame_ended: *mut c_uint,
    compress_continue_state: *const ZSTD_rust_compressContinueState,
    compress_end_state: *const ZSTD_rust_compressEndState,
    reset_session: CompressStreamResetFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressStreamState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_compressStreamState, in_buffer_mode) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, out_buffer_mode)
            == size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, stream_stage)
            == size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, block_size_max)
            == 2 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, stable_in_not_consumed)
            == 3 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, in_buff)
            == 4 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, in_buff_size)
            == 5 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, in_to_compress)
            == 5 * size_of::<usize>() + 2 * size_of::<c_int>() + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, in_buff_pos)
            == 6 * size_of::<usize>() + 2 * size_of::<c_int>() + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, in_buff_target)
            == 7 * size_of::<usize>() + 2 * size_of::<c_int>() + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, out_buff)
            == 9 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, out_buff_size)
            == 9 * size_of::<usize>() + 2 * size_of::<c_int>() + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, out_buff_content_size)
            == 9 * size_of::<usize>() + 2 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, out_buff_flushed_size)
            == 10 * size_of::<usize>() + 2 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, frame_ended)
            == 11 * size_of::<usize>() + 2 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, compress_continue_state)
            == 12 * size_of::<usize>() + 2 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, compress_end_state)
            == 13 * size_of::<usize>() + 2 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamState, reset_session)
            == 14 * size_of::<usize>() + 2 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_compressStreamState>()
            == 15 * size_of::<usize>() + 2 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
};

const ZSTD_RUST_INIT_RESOLVE_BLOCK_SPLITTER: c_int = 0;
const ZSTD_RUST_INIT_RESOLVE_LDM: c_int = 1;
const ZSTD_RUST_INIT_RESOLVE_ROW_MATCH_FINDER: c_int = 2;
const ZSTD_RUST_INIT_RESOLVE_VALIDATE_SEQUENCES: c_int = 3;
const ZSTD_RUST_INIT_RESOLVE_MAX_BLOCK_SIZE: c_int = 4;
const ZSTD_RUST_INIT_RESOLVE_EXTERNAL_REPCODE_SEARCH: c_int = 5;

type CompressStreamInitGetLocalDictFn =
    unsafe extern "C" fn(*mut c_void, *mut ZSTD_rust_compressStreamInitLocalDictState);
type CompressStreamInitCreateLocalDictFn =
    unsafe extern "C" fn(*mut c_void, *mut ZSTD_rust_compressStreamInitLocalDictState) -> usize;
type CompressStreamInitPublishLocalDictFn =
    unsafe extern "C" fn(*mut c_void, *const ZSTD_rust_compressStreamInitLocalDictState);
type CompressStreamInitRefreshCDictFn =
    unsafe extern "C" fn(*mut c_void, *mut ZSTD_rust_compressStreamInitDictionaryState);
type CompressStreamInitClearPrefixFn = unsafe extern "C" fn(*mut c_void);
type CompressStreamInitAssertDictionariesFn = unsafe extern "C" fn(*mut c_void, *const c_void);
type CompressStreamInitSetLevelFn = unsafe extern "C" fn(*mut c_void, c_int);
type CompressStreamInitDebugFn = unsafe extern "C" fn(*mut c_void);
type CompressStreamInitGetPledgedFn = unsafe extern "C" fn(*mut c_void) -> u64;
type CompressStreamInitSetPledgedFn = unsafe extern "C" fn(*mut c_void, usize);
type CompressStreamInitGetCParamModeFn =
    unsafe extern "C" fn(*mut c_void, *const c_void, u64) -> c_int;
type CompressStreamInitBuildCParamsFn = unsafe extern "C" fn(*mut c_void, u64, usize, c_int);
type CompressStreamInitResolveParamsFn = unsafe extern "C" fn(*mut c_void, c_int);
type CompressStreamInitGetNbWorkersFn = unsafe extern "C" fn(*mut c_void) -> c_uint;
type CompressStreamInitSetNbWorkersFn = unsafe extern "C" fn(*mut c_void, c_uint);
type CompressStreamInitHasExtSeqProdFn = unsafe extern "C" fn(*mut c_void) -> c_int;
type CompressStreamInitTraceFn = unsafe extern "C" fn(*mut c_void);
type CompressStreamInitGetMTContextFn = unsafe extern "C" fn(*mut c_void) -> *mut c_void;
type CompressStreamInitCreateMTContextFn = unsafe extern "C" fn(*mut c_void, c_uint) -> usize;
type CompressStreamInitMTFn = unsafe extern "C" fn(
    *mut c_void,
    *mut c_void,
    *const ZSTD_rust_compressStreamInitDictionaryState,
    *mut c_void,
    u64,
) -> usize;
type CompressStreamInitCommitMTFn = unsafe extern "C" fn(
    *mut c_void,
    *const ZSTD_rust_compressStreamInitDictionaryState,
    *mut c_void,
);
type CompressStreamInitCheckCParamsFn = unsafe extern "C" fn(*mut c_void);
type CompressStreamInitBeginFn = unsafe extern "C" fn(
    *mut c_void,
    *const ZSTD_rust_compressStreamInitDictionaryState,
    *mut c_void,
    u64,
) -> usize;
type CompressStreamInitAssertOrdinaryFn = unsafe extern "C" fn(*mut c_void);
type CompressStreamInitGetBufferModeFn = unsafe extern "C" fn(*mut c_void) -> c_int;
type CompressStreamInitGetBlockSizeFn = unsafe extern "C" fn(*mut c_void) -> usize;
type CompressStreamInitCommitOrdinaryFn = unsafe extern "C" fn(*mut c_void, usize);

/// Private local-dictionary projection used by transparent stream initialization.
///
/// Rust owns the no-dictionary, already-initialized, create, and publish order;
/// C retains the private dictionary storage and allocator-sensitive callbacks.
#[repr(C)]
pub struct ZSTD_rust_compressStreamInitLocalDictState {
    dict: *const c_void,
    dict_buffer: *mut c_void,
    dict_size: usize,
    dict_content_type: c_int,
    local_cdict: *mut c_void,
    cdict: *const c_void,
    prefix_dict: *const c_void,
    created_cdict: *mut c_void,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressStreamInitLocalDictState, dict) == 0);
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitLocalDictState, dict_buffer) == size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitLocalDictState, dict_size) == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_compressStreamInitLocalDictState,
            dict_content_type
        ) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitLocalDictState, local_cdict)
            == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitLocalDictState, cdict) == 5 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitLocalDictState, prefix_dict)
            == 6 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitLocalDictState, created_cdict)
            == 7 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_compressStreamInitLocalDictState>() == size_of::<[usize; 8]>());
};

/// Scalar dictionary snapshot used by transparent stream initialization.
///
/// The prefix is populated by C before local-dictionary initialization, which
/// preserves the original single-use snapshot order.  C refreshes only the
/// CDict fields after local-dictionary initialization because that operation
/// may create the local CDict.
#[repr(C)]
pub struct ZSTD_rust_compressStreamInitDictionaryState {
    prefix_dict: *const c_void,
    prefix_dict_size: usize,
    prefix_dict_content_type: c_int,
    cdict: *const c_void,
    cdict_is_local: c_int,
    cdict_compression_level: c_int,
    cdict_dict_content_size: usize,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressStreamInitDictionaryState, prefix_dict) == 0);
    assert!(
        offset_of!(
            ZSTD_rust_compressStreamInitDictionaryState,
            prefix_dict_size
        ) == size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_compressStreamInitDictionaryState,
            prefix_dict_content_type
        ) == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitDictionaryState, cdict) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitDictionaryState, cdict_is_local)
            == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_compressStreamInitDictionaryState,
            cdict_compression_level
        ) == 4 * size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_compressStreamInitDictionaryState,
            cdict_dict_content_size
        ) == 4 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        size_of::<ZSTD_rust_compressStreamInitDictionaryState>()
            == if size_of::<usize>() == 8 { 48 } else { 28 }
    );
};

/// Projection for `ZSTD_CCtx_init_compressStream2()`.
///
/// Rust owns the ordering and branch policy.  The C callback slots retain
/// private parameter/context layouts, local dictionary storage, allocators,
/// trace setup, MT construction/init, and codec/reset operations.
#[repr(C)]
pub struct ZSTD_rust_compressStreamInitState {
    callback_context: *mut c_void,
    params: *mut c_void,
    dictionaries: *mut ZSTD_rust_compressStreamInitDictionaryState,
    end_op: c_int,
    in_size: usize,
    multithreaded: c_int,
    mt_job_size_min: usize,
    get_local_dict: CompressStreamInitGetLocalDictFn,
    create_local_dict: CompressStreamInitCreateLocalDictFn,
    publish_local_dict: CompressStreamInitPublishLocalDictFn,
    refresh_cdict: CompressStreamInitRefreshCDictFn,
    clear_prefix: CompressStreamInitClearPrefixFn,
    assert_dictionaries: CompressStreamInitAssertDictionariesFn,
    set_compression_level: CompressStreamInitSetLevelFn,
    debug_init: CompressStreamInitDebugFn,
    get_pledged_src_size_plus_one: CompressStreamInitGetPledgedFn,
    set_pledged_src_size: CompressStreamInitSetPledgedFn,
    get_cparam_mode: CompressStreamInitGetCParamModeFn,
    build_cparams: CompressStreamInitBuildCParamsFn,
    resolve_params: CompressStreamInitResolveParamsFn,
    get_nb_workers: CompressStreamInitGetNbWorkersFn,
    set_nb_workers: CompressStreamInitSetNbWorkersFn,
    has_ext_seq_prod: CompressStreamInitHasExtSeqProdFn,
    trace_begin: CompressStreamInitTraceFn,
    get_mt_context: CompressStreamInitGetMTContextFn,
    create_mt_context: CompressStreamInitCreateMTContextFn,
    init_mt: CompressStreamInitMTFn,
    commit_mt: CompressStreamInitCommitMTFn,
    check_cparams: CompressStreamInitCheckCParamsFn,
    compress_begin: CompressStreamInitBeginFn,
    assert_ordinary: CompressStreamInitAssertOrdinaryFn,
    get_buffer_mode: CompressStreamInitGetBufferModeFn,
    get_block_size: CompressStreamInitGetBlockSizeFn,
    commit_ordinary: CompressStreamInitCommitOrdinaryFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_compressStreamInitState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_compressStreamInitState, params) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressStreamInitState, dictionaries) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressStreamInitState, end_op) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_compressStreamInitState, in_size) == 4 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitState, multithreaded)
            == 4 * size_of::<usize>() + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_compressStreamInitState, mt_job_size_min)
            == 5 * size_of::<usize>() + size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_compressStreamInitState>()
            == if size_of::<usize>() == 8 { 272 } else { 144 }
    );
};

#[inline]
unsafe fn compress_stream_init_local_dict_with(state: &ZSTD_rust_compressStreamInitState) -> usize {
    let mut local_dict = ZSTD_rust_compressStreamInitLocalDictState {
        dict: ptr::null(),
        dict_buffer: ptr::null_mut(),
        dict_size: 0,
        dict_content_type: 0,
        local_cdict: ptr::null_mut(),
        cdict: ptr::null(),
        prefix_dict: ptr::null(),
        created_cdict: ptr::null_mut(),
    };
    unsafe {
        (state.get_local_dict)(state.callback_context, &mut local_dict);
    }
    if local_dict.dict.is_null() {
        debug_assert!(local_dict.dict_buffer.is_null());
        debug_assert!(local_dict.local_cdict.is_null());
        debug_assert_eq!(local_dict.dict_size, 0);
        return 0;
    }
    if !local_dict.local_cdict.is_null() {
        debug_assert_eq!(local_dict.cdict, local_dict.local_cdict.cast_const(),);
        return 0;
    }
    debug_assert!(local_dict.dict_size > 0);
    debug_assert!(local_dict.cdict.is_null());
    debug_assert!(local_dict.prefix_dict.is_null());

    let result = unsafe { (state.create_local_dict)(state.callback_context, &mut local_dict) };
    if ERR_isError(result) {
        return result;
    }
    debug_assert!(!local_dict.created_cdict.is_null());
    unsafe {
        (state.publish_local_dict)(state.callback_context, &local_dict);
    }
    0
}

#[inline]
unsafe fn compress_stream_init_body_with(state: &ZSTD_rust_compressStreamInitState) -> usize {
    if state.params.is_null() || state.dictionaries.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let result = unsafe { compress_stream_init_local_dict_with(state) };
    if ERR_isError(result) {
        return result;
    }

    unsafe { (state.refresh_cdict)(state.callback_context, state.dictionaries) };
    let dictionaries = unsafe { &*state.dictionaries };
    unsafe { (state.clear_prefix)(state.callback_context) };
    unsafe { (state.assert_dictionaries)(state.callback_context, dictionaries.prefix_dict) };
    if !dictionaries.cdict.is_null() && dictionaries.cdict_is_local == 0 {
        unsafe {
            (state.set_compression_level)(state.params, dictionaries.cdict_compression_level)
        };
    }
    unsafe { (state.debug_init)(state.callback_context) };

    if state.end_op == ZSTD_E_END {
        unsafe { (state.set_pledged_src_size)(state.callback_context, state.in_size) };
    }
    let pledged_src_size_plus_one =
        unsafe { (state.get_pledged_src_size_plus_one)(state.callback_context) };
    let pledged_src_size = pledged_src_size_plus_one.wrapping_sub(1);
    let dict_size = if !dictionaries.prefix_dict.is_null() {
        dictionaries.prefix_dict_size
    } else if !dictionaries.cdict.is_null() {
        dictionaries.cdict_dict_content_size
    } else {
        0
    };
    let mode =
        unsafe { (state.get_cparam_mode)(state.params, dictionaries.cdict, pledged_src_size) };
    unsafe {
        (state.build_cparams)(state.params, pledged_src_size, dict_size, mode);
        (state.resolve_params)(state.params, ZSTD_RUST_INIT_RESOLVE_BLOCK_SPLITTER);
        (state.resolve_params)(state.params, ZSTD_RUST_INIT_RESOLVE_LDM);
        (state.resolve_params)(state.params, ZSTD_RUST_INIT_RESOLVE_ROW_MATCH_FINDER);
        (state.resolve_params)(state.params, ZSTD_RUST_INIT_RESOLVE_VALIDATE_SEQUENCES);
        (state.resolve_params)(state.params, ZSTD_RUST_INIT_RESOLVE_MAX_BLOCK_SIZE);
        (state.resolve_params)(state.params, ZSTD_RUST_INIT_RESOLVE_EXTERNAL_REPCODE_SEARCH);
    }

    if state.multithreaded != 0 {
        let has_ext_seq_prod = unsafe { (state.has_ext_seq_prod)(state.params) };
        let mut nb_workers = unsafe { (state.get_nb_workers)(state.params) };
        if has_ext_seq_prod != 0 && nb_workers >= 1 {
            return ERROR(ZstdErrorCode::ParameterCombinationUnsupported);
        }
        if pledged_src_size <= state.mt_job_size_min as u64 {
            nb_workers = 0;
            unsafe { (state.set_nb_workers)(state.params, 0) };
        }
        if nb_workers > 0 {
            unsafe { (state.trace_begin)(state.callback_context) };
            if unsafe { (state.get_mt_context)(state.callback_context) }.is_null() {
                let result =
                    unsafe { (state.create_mt_context)(state.callback_context, nb_workers) };
                if ERR_isError(result) {
                    return result;
                }
            }
            let result = unsafe {
                (state.init_mt)(
                    state.callback_context,
                    (state.get_mt_context)(state.callback_context),
                    dictionaries,
                    state.params,
                    pledged_src_size,
                )
            };
            if ERR_isError(result) {
                return result;
            }
            unsafe { (state.commit_mt)(state.callback_context, dictionaries, state.params) };
            return 0;
        }
    }

    unsafe { (state.check_cparams)(state.params) };
    let result = unsafe {
        (state.compress_begin)(
            state.callback_context,
            dictionaries,
            state.params,
            pledged_src_size,
        )
    };
    if ERR_isError(result) {
        return result;
    }
    unsafe { (state.assert_ordinary)(state.callback_context) };
    let buffer_mode = unsafe { (state.get_buffer_mode)(state.callback_context) };
    let block_size = unsafe { (state.get_block_size)(state.callback_context) };
    let in_buff_target = if buffer_mode == ZSTD_BM_BUFFERED {
        block_size.wrapping_add(usize::from(block_size as u64 == pledged_src_size))
    } else {
        0
    };
    unsafe { (state.commit_ordinary)(state.callback_context, in_buff_target) };
    0
}

/// Rust-owned high-level policy for transparent stream initialization.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressStreamInit(
    state: *const ZSTD_rust_compressStreamInitState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe { compress_stream_init_body_with(&*state) }
}

#[inline]
unsafe fn stream_limit_copy(
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    let length = dst_capacity.min(src_size);
    if length != 0 {
        unsafe {
            ptr::copy_nonoverlapping(src.cast::<u8>(), dst.cast::<u8>(), length);
        }
    }
    length
}

#[inline]
unsafe fn compress_stream_generic_body_with(
    state: &ZSTD_rust_compressStreamState,
    output: &mut ZSTD_outBuffer,
    input: &mut ZSTD_inBuffer,
    flush_mode: c_int,
) -> usize {
    debug_assert!((ZSTD_E_CONTINUE..=ZSTD_E_END).contains(&flush_mode));
    debug_assert!(input.pos <= input.size);
    debug_assert!(output.pos <= output.size);
    debug_assert!(!input.src.is_null() || input.size == 0);
    debug_assert!(!output.dst.is_null() || output.size == 0);

    if state.stream_stage.is_null()
        || state.stable_in_not_consumed.is_null()
        || state.in_to_compress.is_null()
        || state.in_buff_pos.is_null()
        || state.in_buff_target.is_null()
        || state.out_buff_content_size.is_null()
        || state.out_buff_flushed_size.is_null()
        || state.frame_ended.is_null()
        || state.compress_continue_state.is_null()
        || state.compress_end_state.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    if state.in_buffer_mode == ZSTD_BM_STABLE {
        let stable = unsafe { *state.stable_in_not_consumed };
        debug_assert!(input.pos >= stable);
        input.pos = input.pos.wrapping_sub(stable);
        *unsafe { state.stable_in_not_consumed.as_mut().unwrap_unchecked() } = 0;
    }

    debug_assert!(
        state.in_buffer_mode == ZSTD_BM_BUFFERED || state.in_buffer_mode == ZSTD_BM_STABLE
    );
    if state.in_buffer_mode == ZSTD_BM_BUFFERED {
        debug_assert!(!state.in_buff.is_null());
        debug_assert!(state.in_buff_size != 0);
    }
    if state.out_buffer_mode == ZSTD_BM_BUFFERED {
        debug_assert!(!state.out_buff.is_null());
        debug_assert!(state.out_buff_size != 0);
    }

    let mut some_more_work = true;
    while some_more_work {
        let stage = unsafe { *state.stream_stage };
        match stage {
            ZSTD_CSTREAM_STAGE_INIT => return ERROR(ZstdErrorCode::InitMissing),
            ZSTD_CSTREAM_STAGE_LOAD => {
                let input_remaining = input.size - input.pos;
                let output_remaining = output.size - output.pos;
                let bound = crate::zstd_compress_api::ZSTD_compressBound(input_remaining);
                if flush_mode == ZSTD_E_END
                    && (output_remaining >= bound || state.out_buffer_mode == ZSTD_BM_STABLE)
                    && unsafe { *state.in_buff_pos } == 0
                {
                    let dst = if output.dst.is_null() {
                        ptr::null_mut()
                    } else {
                        unsafe { output.dst.cast::<u8>().add(output.pos).cast() }
                    };
                    let src = if input.src.is_null() {
                        ptr::null()
                    } else {
                        unsafe { input.src.cast::<u8>().add(input.pos).cast() }
                    };
                    let c_size = unsafe {
                        ZSTD_rust_compressEnd(
                            state.compress_end_state,
                            dst,
                            output_remaining,
                            src,
                            input_remaining,
                        )
                    };
                    if ERR_isError(c_size) {
                        return c_size;
                    }
                    input.pos = input.size;
                    output.pos += c_size;
                    unsafe { *state.frame_ended = 1 };
                    unsafe { (state.reset_session)(state.callback_context) };
                    some_more_work = false;
                    continue;
                }

                if state.in_buffer_mode == ZSTD_BM_BUFFERED {
                    let to_load =
                        unsafe { (*state.in_buff_target).wrapping_sub(*state.in_buff_pos) };
                    let src = if input.src.is_null() {
                        ptr::null()
                    } else {
                        unsafe { input.src.cast::<u8>().add(input.pos).cast() }
                    };
                    let dst = if state.in_buff.is_null() {
                        ptr::null_mut()
                    } else {
                        unsafe { state.in_buff.cast::<u8>().add(*state.in_buff_pos).cast() }
                    };
                    let loaded = unsafe { stream_limit_copy(dst, to_load, src, input_remaining) };
                    input.pos += loaded;
                    unsafe { *state.in_buff_pos += loaded };

                    if flush_mode == ZSTD_E_CONTINUE
                        && unsafe { *state.in_buff_pos < *state.in_buff_target }
                    {
                        some_more_work = false;
                        continue;
                    }
                    if flush_mode == ZSTD_E_FLUSH
                        && unsafe { *state.in_buff_pos == *state.in_to_compress }
                    {
                        some_more_work = false;
                        continue;
                    }
                } else {
                    debug_assert_eq!(state.in_buffer_mode, ZSTD_BM_STABLE);
                    let input_remaining = input.size - input.pos;
                    if flush_mode == ZSTD_E_CONTINUE && input_remaining < state.block_size_max {
                        unsafe { *state.stable_in_not_consumed = input_remaining };
                        input.pos = input.size;
                        some_more_work = false;
                        continue;
                    }
                    if flush_mode == ZSTD_E_FLUSH && input.pos == input.size {
                        some_more_work = false;
                        continue;
                    }
                }

                let input_buffered = state.in_buffer_mode == ZSTD_BM_BUFFERED;
                let mut output_size = output.size - output.pos;
                let input_size = if input_buffered {
                    unsafe { (*state.in_buff_pos).wrapping_sub(*state.in_to_compress) }
                } else {
                    (input.size - input.pos).min(state.block_size_max)
                };
                let output_dst = if output_size
                    >= crate::zstd_compress_api::ZSTD_compressBound(input_size)
                    || state.out_buffer_mode == ZSTD_BM_STABLE
                {
                    if output.dst.is_null() {
                        ptr::null_mut()
                    } else {
                        unsafe { output.dst.cast::<u8>().add(output.pos).cast() }
                    }
                } else {
                    output_size = state.out_buff_size;
                    state.out_buff
                };

                let last_block = flush_mode == ZSTD_E_END
                    && if input_buffered {
                        input.pos == input.size
                    } else {
                        input.pos + input_size == input.size
                    };
                let source = if input_buffered {
                    if state.in_buff.is_null() {
                        ptr::null()
                    } else {
                        unsafe { state.in_buff.cast::<u8>().add(*state.in_to_compress).cast() }
                    }
                } else if input.src.is_null() {
                    ptr::null()
                } else {
                    unsafe { input.src.cast::<u8>().add(input.pos).cast() }
                };
                let c_size = unsafe {
                    if last_block {
                        ZSTD_rust_compressEnd(
                            state.compress_end_state,
                            output_dst,
                            output_size,
                            source,
                            input_size,
                        )
                    } else {
                        ZSTD_rust_compressContinue(
                            state.compress_continue_state,
                            output_dst,
                            output_size,
                            source,
                            input_size,
                            1,
                            0,
                        )
                    }
                };
                if !input_buffered {
                    /* Match C: stable input is consumed before forwarding a
                     * compression error. */
                    input.pos += input_size;
                }
                if ERR_isError(c_size) {
                    return c_size;
                }

                unsafe { *state.frame_ended = c_uint::from(last_block) };
                if input_buffered {
                    unsafe {
                        *state.in_buff_target =
                            (*state.in_buff_pos).wrapping_add(state.block_size_max);
                        if *state.in_buff_target > state.in_buff_size {
                            *state.in_buff_pos = 0;
                            *state.in_buff_target = state.block_size_max;
                        }
                        *state.in_to_compress = *state.in_buff_pos;
                    }
                }

                let current_output = if output.dst.is_null() {
                    ptr::null_mut()
                } else {
                    unsafe { output.dst.cast::<u8>().add(output.pos).cast() }
                };
                if output_dst == current_output {
                    output.pos += c_size;
                    if unsafe { *state.frame_ended } != 0 {
                        unsafe { (state.reset_session)(state.callback_context) };
                        some_more_work = false;
                    }
                    continue;
                }

                unsafe {
                    *state.out_buff_content_size = c_size;
                    *state.out_buff_flushed_size = 0;
                    *state.stream_stage = ZSTD_CSTREAM_STAGE_FLUSH;
                }
            }
            ZSTD_CSTREAM_STAGE_FLUSH => {
                debug_assert_eq!(state.out_buffer_mode, ZSTD_BM_BUFFERED);
                let to_flush = unsafe {
                    (*state.out_buff_content_size).wrapping_sub(*state.out_buff_flushed_size)
                };
                let src = if state.out_buff.is_null() {
                    ptr::null()
                } else {
                    unsafe {
                        state
                            .out_buff
                            .cast::<u8>()
                            .add(*state.out_buff_flushed_size)
                            .cast()
                    }
                };
                let dst = if output.dst.is_null() {
                    ptr::null_mut()
                } else {
                    unsafe { output.dst.cast::<u8>().add(output.pos).cast() }
                };
                let flushed =
                    unsafe { stream_limit_copy(dst, output.size - output.pos, src, to_flush) };
                output.pos += flushed;
                unsafe { *state.out_buff_flushed_size += flushed };
                if to_flush != flushed {
                    some_more_work = false;
                    continue;
                }

                unsafe {
                    *state.out_buff_content_size = 0;
                    *state.out_buff_flushed_size = 0;
                }
                if unsafe { *state.frame_ended } != 0 {
                    unsafe { (state.reset_session)(state.callback_context) };
                    some_more_work = false;
                    continue;
                }
                unsafe { *state.stream_stage = ZSTD_CSTREAM_STAGE_LOAD };
            }
            _ => {
                debug_assert!(false, "invalid C stream stage");
                return ERROR(ZstdErrorCode::StageWrong);
            }
        }
    }

    if unsafe { *state.frame_ended } != 0 {
        return 0;
    }
    next_input_size_hint(
        state.in_buffer_mode,
        state.block_size_max,
        unsafe { *state.stable_in_not_consumed },
        unsafe { *state.in_buff_target },
        unsafe { *state.in_buff_pos },
    )
}

/// Drive the single-threaded stream state machine through a C-owned context.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressStreamGeneric(
    state: *const ZSTD_rust_compressStreamState,
    output: *mut ZSTD_outBuffer,
    input: *mut ZSTD_inBuffer,
    flush_mode: c_int,
) -> usize {
    if state.is_null() || output.is_null() || input.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe { compress_stream_generic_body_with(&*state, &mut *output, &mut *input, flush_mode) }
}

/// Explicit projection of the state used by `ZSTD_compressSequences_internal`.
///
/// The C context and its function-pointer-bearing parameter structure remain
/// private to C.  Only the sequence store, compressed-block state slots, and
/// scalar policy/workspace fields read by the per-block loop cross the ABI.
#[repr(C)]
pub struct ZSTD_rust_sequenceCompressionState {
    seq_store: *mut SeqStore_t,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
    tmp_workspace: *mut c_void,
    tmp_wksp_size: usize,
    block_size_max: usize,
    bmi2: c_int,
    block_delimiters: c_int,
    strategy: c_int,
    disable_literal_compression: c_int,
    search_for_external_repcodes: c_int,
    validate_sequences: c_int,
    min_match: c_uint,
    window_log: c_uint,
    dict_size: c_uint,
    use_sequence_producer: c_int,
    is_first_block: *mut c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_sequenceCompressionState, seq_store) == 0);
    assert!(offset_of!(ZSTD_rust_sequenceCompressionState, prev_c_block) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_sequenceCompressionState, next_c_block) == 2 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_sequenceCompressionState, tmp_workspace) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceCompressionState, tmp_wksp_size) == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceCompressionState, block_size_max) == 5 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_sequenceCompressionState, bmi2) == 6 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_sequenceCompressionState, min_match)
            == 6 * size_of::<usize>() + 6 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceCompressionState, use_sequence_producer)
            == 6 * size_of::<usize>() + 6 * size_of::<c_int>() + 3 * size_of::<c_uint>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceCompressionState, is_first_block)
            == 6 * size_of::<usize>() + 7 * size_of::<c_int>() + 3 * size_of::<c_uint>()
    );
    assert!(
        size_of::<ZSTD_rust_sequenceCompressionState>()
            == if size_of::<usize>() == 8 { 96 } else { 68 }
    );
};

/// C callback signature for the CCtx-dependent sequence conversion leaf.
type SequenceLiteralsConvertFn =
    unsafe extern "C" fn(*mut c_void, *const ZSTD_Sequence, usize, c_int) -> usize;

/// Explicit projection of the state used by
/// ZSTD_compressSequencesAndLiterals_internal.
///
/// CCtx initialization, parameter validation, and the sequence conversion
/// callback remain in C. Rust owns the block loop, external literal cursor,
/// entropy invocation, block framing, and per-frame completion checks.
#[repr(C)]
pub struct ZSTD_rust_sequenceLiteralsState {
    seq_store: *mut SeqStore_t,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
    tmp_workspace: *mut c_void,
    tmp_wksp_size: usize,
    block_size_max: usize,
    bmi2: c_int,
    strategy: c_int,
    disable_literal_compression: c_int,
    repcode_resolution: c_int,
    is_first_block: *mut c_int,
    callback_context: *mut c_void,
    convert_block_sequences: SequenceLiteralsConvertFn,
}

/// Explicit projection for the public block-sequence conversion entry point.
/// The surrounding `ZSTD_CCtx` remains opaque; only the sequence store and
/// compressed-block repcode slots are needed by the converter.
#[repr(C)]
pub struct ZSTD_rust_convertBlockSequencesState {
    seq_store: *mut SeqStore_t,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_convertBlockSequencesState, seq_store) == 0);
    assert!(offset_of!(ZSTD_rust_convertBlockSequencesState, prev_c_block) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_convertBlockSequencesState, next_c_block) == 2 * size_of::<usize>()
    );
    assert!(size_of::<ZSTD_rust_convertBlockSequencesState>() == 3 * size_of::<usize>());
};

const _: () = {
    assert!(offset_of!(ZSTD_rust_sequenceLiteralsState, seq_store) == 0);
    assert!(offset_of!(ZSTD_rust_sequenceLiteralsState, prev_c_block) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_sequenceLiteralsState, next_c_block) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_sequenceLiteralsState, tmp_workspace) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_sequenceLiteralsState, tmp_wksp_size) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_sequenceLiteralsState, block_size_max) == 5 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_sequenceLiteralsState, bmi2) == 6 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_sequenceLiteralsState, strategy)
            == 6 * size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceLiteralsState, disable_literal_compression)
            == 6 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceLiteralsState, repcode_resolution)
            == 6 * size_of::<usize>() + 3 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceLiteralsState, is_first_block)
            == 6 * size_of::<usize>() + 4 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceLiteralsState, callback_context)
            == 6 * size_of::<usize>() + 4 * size_of::<c_int>() + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceLiteralsState, convert_block_sequences)
            == 6 * size_of::<usize>() + 4 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_sequenceLiteralsState>()
            == 6 * size_of::<usize>() + 4 * size_of::<c_int>() + 3 * size_of::<usize>()
    );
};

type SequenceApiInitFn =
    unsafe extern "C" fn(*mut c_void, usize, *mut ZSTD_rust_sequenceApiState) -> usize;

/// Explicit projection for the public sequence-compression API orchestration.
///
/// Rust owns validation ordering, frame-header/checksum sequencing, and
/// output accounting.  Frame-header parameters are projected as scalars; C
/// retains the private CCtx and sequence-store/block layouts through the
/// initialization callback and two block-state projections.  The XXH64 state
/// is projected directly so checksum updates and serialization stay in Rust.
#[repr(C)]
pub struct ZSTD_rust_sequenceApiState {
    callback_context: *mut c_void,
    sequence_state: *mut ZSTD_rust_sequenceCompressionState,
    sequence_literals_state: *mut ZSTD_rust_sequenceLiteralsState,
    init: SequenceApiInitFn,
    checksum_state: *mut XXH64_state_t,
    checksum_flag: c_int,
    block_delimiters: c_int,
    validate_sequences: c_int,
    no_dict_id_flag: c_int,
    content_size_flag: c_int,
    format: c_int,
    window_log: c_uint,
    dict_id: c_uint,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_sequenceApiState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_sequenceApiState, sequence_state) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_sequenceApiState, sequence_literals_state) == 2 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_sequenceApiState, init) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_sequenceApiState, checksum_state) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_sequenceApiState, checksum_flag) == size_of::<[usize; 5]>());
    assert!(
        offset_of!(ZSTD_rust_sequenceApiState, block_delimiters)
            == size_of::<[usize; 5]>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceApiState, validate_sequences)
            == size_of::<[usize; 5]>() + size_of::<[c_int; 2]>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceApiState, no_dict_id_flag)
            == size_of::<[usize; 5]>() + size_of::<[c_int; 3]>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceApiState, content_size_flag)
            == size_of::<[usize; 5]>() + size_of::<[c_int; 4]>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceApiState, format)
            == size_of::<[usize; 5]>() + size_of::<[c_int; 5]>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceApiState, window_log)
            == size_of::<[usize; 5]>() + size_of::<[c_int; 6]>()
    );
    assert!(
        offset_of!(ZSTD_rust_sequenceApiState, dict_id)
            == size_of::<[usize; 5]>() + size_of::<[c_int; 6]>() + size_of::<c_uint>()
    );
    assert!(
        size_of::<ZSTD_rust_sequenceApiState>() == if size_of::<usize>() == 8 { 72 } else { 52 }
    );
};

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
struct SequenceApiPlan {
    update_input_checksum: bool,
    append_frame_checksum: bool,
}

/// Apply the public sequence API's post-initialization validation policy.
///
/// The order is intentional and matches the C entry point: the literals
/// variant rejects no-delimiter mode first, then sequence validation, then a
/// frame checksum.  The ordinary variant permits all three independently.
fn sequence_api_plan(
    with_literals: bool,
    block_delimiters: c_int,
    validate_sequences: c_int,
    checksum_flag: c_int,
) -> Result<SequenceApiPlan, usize> {
    if with_literals {
        if block_delimiters == ZSTD_SF_NO_BLOCK_DELIMITERS {
            return Err(ERROR(ZstdErrorCode::FrameParameterUnsupported));
        }
        if validate_sequences != 0 {
            return Err(ERROR(ZstdErrorCode::ParameterUnsupported));
        }
        if checksum_flag != 0 {
            return Err(ERROR(ZstdErrorCode::FrameParameterUnsupported));
        }
        return Ok(SequenceApiPlan {
            update_input_checksum: false,
            append_frame_checksum: false,
        });
    }

    Ok(SequenceApiPlan {
        update_input_checksum: checksum_flag != 0,
        append_frame_checksum: checksum_flag != 0,
    })
}

#[inline]
fn sequence_api_validate_literal_capacity(lit_size: usize, lit_capacity: usize) -> usize {
    if lit_capacity < lit_size {
        ERROR(ZstdErrorCode::WorkSpaceTooSmall)
    } else {
        0
    }
}

/// Explicit projection of the state used by `ZSTD_compressSeqStore_singleBlock`.
///
/// Sequence-store construction and split discovery remain in C. Only the
/// sequence store, simulated repcode histories, compressed-block state slots,
/// sequence collector, and scalar compression settings cross the ABI.
#[repr(C)]
pub struct ZSTD_rust_seqStoreSingleBlockState {
    seq_store: *const SeqStore_t,
    d_rep: *mut u32,
    c_rep: *mut u32,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
    tmp_workspace: *mut c_void,
    tmp_wksp_size: usize,
    seq_collector: *mut SeqCollector,
    strategy: c_int,
    disable_literal_compression: c_int,
    bmi2: c_int,
    is_first_block: c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_seqStoreSingleBlockState, seq_store) == 0);
    assert!(offset_of!(ZSTD_rust_seqStoreSingleBlockState, d_rep) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_seqStoreSingleBlockState, c_rep) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_seqStoreSingleBlockState, prev_c_block) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_seqStoreSingleBlockState, next_c_block) == 4 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_seqStoreSingleBlockState, tmp_workspace) == 5 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_seqStoreSingleBlockState, tmp_wksp_size) == 6 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_seqStoreSingleBlockState, seq_collector) == 7 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_seqStoreSingleBlockState, strategy) == usize::BITS as usize);
    assert!(
        offset_of!(
            ZSTD_rust_seqStoreSingleBlockState,
            disable_literal_compression
        ) == usize::BITS as usize + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_seqStoreSingleBlockState, bmi2)
            == usize::BITS as usize + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_seqStoreSingleBlockState, is_first_block)
            == usize::BITS as usize + 3 * size_of::<c_int>()
    );
    assert!(
        size_of::<ZSTD_rust_seqStoreSingleBlockState>()
            == usize::BITS as usize + 4 * size_of::<c_int>()
    );
};

/// Explicit projection of the state used by the post-split partition loop.
///
/// The C caller still owns the private compression context and derives the
/// partition boundaries. Rust owns the partition accounting, repcode
/// simulation, and repeated single-block dispatch.
#[repr(C)]
pub struct ZSTD_rust_splitBlockState {
    seq_store: *const SeqStore_t,
    partitions: *const u32,
    next_seq_store: *mut SeqStore_t,
    curr_seq_store: *mut SeqStore_t,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
    tmp_workspace: *mut c_void,
    tmp_wksp_size: usize,
    seq_collector: *mut SeqCollector,
    block_size_max: usize,
    strategy: c_int,
    disable_literal_compression: c_int,
    bmi2: c_int,
    is_first_block: c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_splitBlockState, seq_store) == 0);
    assert!(offset_of!(ZSTD_rust_splitBlockState, partitions) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_splitBlockState, next_seq_store) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_splitBlockState, curr_seq_store) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_splitBlockState, prev_c_block) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_splitBlockState, next_c_block) == 5 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_splitBlockState, tmp_workspace) == 6 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_splitBlockState, tmp_wksp_size) == 7 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_splitBlockState, seq_collector) == usize::BITS as usize);
    assert!(offset_of!(ZSTD_rust_splitBlockState, block_size_max) == 9 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_splitBlockState, strategy) == 10 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_splitBlockState, disable_literal_compression)
            == 10 * size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_splitBlockState, bmi2)
            == 10 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_splitBlockState, is_first_block)
            == 10 * size_of::<usize>() + 3 * size_of::<c_int>()
    );
    assert!(
        size_of::<ZSTD_rust_splitBlockState>() == 10 * size_of::<usize>() + 4 * size_of::<c_int>()
    );
};

/// Explicit projection of the state used by `ZSTD_compressBlock_internal`.
///
/// Sequence-store construction enters through an explicit build-state
/// projection. Rust owns sequence collection, entropy emission, the legacy
/// first-block RLE gate, and the compressed-block state transitions after the
/// store is ready.
#[repr(C)]
pub struct ZSTD_rust_blockInternalState {
    seq_store: *const SeqStore_t,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
    tmp_workspace: *mut c_void,
    tmp_wksp_size: usize,
    seq_collector: *mut SeqCollector,
    strategy: c_int,
    disable_literal_compression: c_int,
    bmi2: c_int,
    is_first_block: c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_blockInternalState, seq_store) == 0);
    assert!(offset_of!(ZSTD_rust_blockInternalState, prev_c_block) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_blockInternalState, next_c_block) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_blockInternalState, tmp_workspace) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_blockInternalState, tmp_wksp_size) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_blockInternalState, seq_collector) == 5 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_blockInternalState, strategy) == 6 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_blockInternalState, disable_literal_compression)
            == 6 * size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_blockInternalState, bmi2)
            == 6 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_blockInternalState, is_first_block)
            == 6 * size_of::<usize>() + 3 * size_of::<c_int>()
    );
    assert!(
        size_of::<ZSTD_rust_blockInternalState>()
            == 6 * size_of::<usize>() + 4 * size_of::<c_int>()
    );
};

/// Explicit projection of the state used by the target-sized block body.
///
/// Sequence-store construction and the matchfinder remain in C.  This state
/// contains only the already-Rust-owned block-compression inputs and the two
/// pointer slots that the compressed-block confirmation leaf swaps.
#[repr(C)]
pub struct ZSTD_rust_targetCBlockSizeState {
    seq_store: *mut SeqStore_t,
    prev_c_block: *mut *mut ZSTD_compressedBlockState_t,
    next_c_block: *mut *mut ZSTD_compressedBlockState_t,
    tmp_workspace: *mut c_void,
    tmp_wksp_size: usize,
    strategy: c_int,
    disable_literal_compression: c_int,
    bmi2: c_int,
    window_log: c_uint,
    target_c_block_size: usize,
    is_first_block: c_int,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_targetCBlockSizeState, seq_store) == 0);
    assert!(offset_of!(ZSTD_rust_targetCBlockSizeState, prev_c_block) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_targetCBlockSizeState, next_c_block) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_targetCBlockSizeState, tmp_workspace) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_targetCBlockSizeState, tmp_wksp_size) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_targetCBlockSizeState, strategy) == 5 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_targetCBlockSizeState, disable_literal_compression)
            == 5 * size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_targetCBlockSizeState, bmi2)
            == 5 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_targetCBlockSizeState, window_log)
            == 5 * size_of::<usize>() + 3 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_targetCBlockSizeState, target_c_block_size)
            == 5 * size_of::<usize>() + 4 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_targetCBlockSizeState, is_first_block)
            == 5 * size_of::<usize>() + 4 * size_of::<c_int>() + size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_targetCBlockSizeState>()
            == if size_of::<usize>() == 8 { 72 } else { 44 }
    );
};

#[repr(i32)]
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
enum TargetCBlockAction {
    Raw = 0,
    Rle = 1,
    Compressed = 2,
    Error = 3,
}

#[derive(Debug, Copy, Clone, PartialEq, Eq)]
enum SequenceBlockAction {
    Raw,
    Rle,
    Compressed,
}

type SingleBlockEntropyFn = unsafe extern "C" fn(
    *const SeqStore_t,
    *const ZSTD_entropyCTables_t,
    *mut ZSTD_entropyCTables_t,
    c_int,
    c_int,
    *mut c_void,
    usize,
    usize,
    *mut c_void,
    usize,
    c_int,
) -> usize;
type SingleBlockResolveOffCodesFn =
    unsafe extern "C" fn(*mut u32, *mut u32, *const SeqStore_t, c_uint);
type SingleBlockCopySequencesFn =
    unsafe extern "C" fn(*mut SeqCollector, *const SeqStore_t, *const u32) -> usize;
type SingleBlockConfirmFn = unsafe extern "C" fn(
    *mut *mut ZSTD_compressedBlockState_t,
    *mut *mut ZSTD_compressedBlockState_t,
);
type SingleBlockRawFn =
    unsafe extern "C" fn(*mut c_void, usize, *const c_void, usize, c_uint) -> usize;
type SingleBlockRleFn = unsafe extern "C" fn(*mut c_void, usize, u8, usize, c_uint) -> usize;
type SingleBlockWriteHeaderFn = unsafe extern "C" fn(*mut c_void, usize, usize, c_uint);
type SingleBlockIsRleFn = unsafe extern "C" fn(*const u8, usize) -> c_int;

#[derive(Clone, Copy)]
struct SingleBlockSeams {
    entropy_compress: SingleBlockEntropyFn,
    resolve_off_codes: SingleBlockResolveOffCodesFn,
    copy_sequences: SingleBlockCopySequencesFn,
    confirm: SingleBlockConfirmFn,
    raw: SingleBlockRawFn,
    rle: SingleBlockRleFn,
    write_header: SingleBlockWriteHeaderFn,
    is_rle: SingleBlockIsRleFn,
}

impl SingleBlockSeams {
    fn production() -> Self {
        Self {
            entropy_compress: ZSTD_rust_entropyCompressSeqStore,
            resolve_off_codes: ZSTD_rust_seqStore_resolveOffCodes,
            copy_sequences: ZSTD_rust_copyBlockSequences,
            confirm: ZSTD_rust_confirmRepcodesAndEntropyTables,
            raw: ZSTD_rust_noCompressBlock,
            rle: ZSTD_rust_rleCompressBlock,
            write_header: ZSTD_rust_writeBlockHeader,
            is_rle: ZSTD_rust_isRLE,
        }
    }
}

/// Rust-owned sequence-store branch policy. C callbacks perform the
/// operations which need the private matchfinder or CCtx
/// parameter/function-pointer state.
#[allow(clippy::too_many_arguments)]
unsafe fn build_seq_store_select_sequences_body_with(
    state: &ZSTD_rust_buildSeqStoreState,
    seq_store: *mut SeqStore_t,
    next_rep: *mut u32,
    src: *const c_void,
    src_size: usize,
    seq_store_complete: &mut c_int,
) -> usize {
    if seq_store.is_null()
        || next_rep.is_null()
        || src.is_null()
        || state.compress_external_sequences as usize == 0
        || state.compress_ldm as usize == 0
        || state.try_external_sequence_producer as usize == 0
        || state.compress_internal as usize == 0
        || state.clear_ldm_seq_store as usize == 0
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    *seq_store_complete = 0;
    if state.has_external_sequences != 0 {
        if state.has_external_sequence_producer != 0 {
            return ERROR(ZstdErrorCode::ParameterCombinationUnsupported);
        }
        return unsafe {
            (state.compress_external_sequences)(
                state.callback_context,
                seq_store,
                next_rep,
                src,
                src_size,
            )
        };
    }

    if state.ldm_enabled != 0 {
        if state.has_external_sequence_producer != 0 {
            return ERROR(ZstdErrorCode::ParameterCombinationUnsupported);
        }
        return unsafe {
            (state.compress_ldm)(state.callback_context, seq_store, next_rep, src, src_size)
        };
    }

    if state.has_external_sequence_producer != 0 {
        let mut allow_fallback = 0;
        let producer_result = unsafe {
            (state.try_external_sequence_producer)(
                state.callback_context,
                src,
                src_size,
                seq_store_complete,
                &mut allow_fallback,
            )
        };
        if *seq_store_complete != 0 {
            unsafe { (state.clear_ldm_seq_store)(state.callback_context) };
            return producer_result;
        }
        if allow_fallback == 0 || state.enable_match_finder_fallback == 0 {
            return producer_result;
        }
        unsafe { (state.clear_ldm_seq_store)(state.callback_context) };
        return unsafe {
            (state.compress_internal)(state.callback_context, seq_store, next_rep, src, src_size)
        };
    }

    unsafe { (state.clear_ldm_seq_store)(state.callback_context) };
    unsafe { (state.compress_internal)(state.callback_context, seq_store, next_rep, src, src_size) }
}

/// Rust-owned sequence-store boundary. C callbacks perform the operations
/// which need the private matchfinder or CCtx parameter/function-pointer state.
#[allow(clippy::too_many_arguments)]
unsafe fn build_seq_store_body_with(
    state: &ZSTD_rust_buildSeqStoreState,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if state.seq_store.is_null()
        || state.skip_small_block as usize == 0
        || state.prepare_match_state as usize == 0
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    if src_size > ZSTD_BLOCKSIZE_MAX {
        return ERROR(ZstdErrorCode::SrcSizeWrong);
    }

    if src_size < MIN_COMPRESSIBLE_BLOCK_SIZE {
        unsafe { (state.skip_small_block)(state.callback_context, src_size) };
        return ZSTD_BSS_NO_COMPRESS as usize;
    }

    if src.is_null() || state.prev_c_block.is_null() || state.next_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let prev_c_block = unsafe { *state.prev_c_block };
    let next_c_block = unsafe { *state.next_c_block };
    if prev_c_block.is_null() || next_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    unsafe { ZSTD_rust_resetSeqStore(state.seq_store) };
    unsafe {
        (state.prepare_match_state)(state.callback_context, src, src_size);
    }

    unsafe {
        ptr::copy_nonoverlapping(
            (*prev_c_block).rep.as_ptr(),
            (*next_c_block).rep.as_mut_ptr(),
            ZSTD_REP_NUM,
        );
    }

    let mut seq_store_complete = 0;
    let last_literals_size = unsafe {
        build_seq_store_select_sequences_body_with(
            state,
            state.seq_store,
            (*next_c_block).rep.as_mut_ptr(),
            src,
            src_size,
            &mut seq_store_complete,
        )
    };
    if ERR_isError(last_literals_size) {
        return last_literals_size;
    }
    if seq_store_complete != 0 {
        return ZSTD_BSS_COMPRESS as usize;
    }
    if last_literals_size > src_size {
        return ERROR(ZstdErrorCode::Generic);
    }

    unsafe {
        ZSTD_rust_storeLastLiterals(
            state.seq_store,
            src.cast::<u8>().add(src_size - last_literals_size),
            last_literals_size,
        );
    }
    if state.validate_seq_store != 0 {
        unsafe { ZSTD_rust_validateSeqStore(state.seq_store, state.min_match) };
    }
    ZSTD_BSS_COMPRESS as usize
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_buildSeqStore(
    state: *const ZSTD_rust_buildSeqStoreState,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe { build_seq_store_body_with(&*state, src, src_size) }
}

/// Rust implementation of `ZSTD_compressBlock_internal` after the C caller
/// has built the sequence store.
#[allow(clippy::too_many_arguments)]
unsafe fn compress_block_internal_body_with(
    state: &ZSTD_rust_blockInternalState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    frame: c_uint,
    seams: SingleBlockSeams,
) -> usize {
    const RLE_MAX_LENGTH: usize = 25;
    const FSE_REPEAT_CHECK: c_int = 1;
    const FSE_REPEAT_VALID: c_int = 2;

    if state.seq_store.is_null()
        || state.prev_c_block.is_null()
        || state.next_c_block.is_null()
        || state.seq_collector.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    let prev_c_block = unsafe { *state.prev_c_block };
    let next_c_block = unsafe { *state.next_c_block };
    if prev_c_block.is_null() || next_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    if unsafe { (*state.seq_collector).collectSequences } != 0 {
        let result = unsafe {
            (seams.copy_sequences)(
                state.seq_collector,
                state.seq_store,
                (*prev_c_block).rep.as_ptr(),
            )
        };
        if ERR_isError(result) {
            return result;
        }
        unsafe { (seams.confirm)(state.prev_c_block, state.next_c_block) };
        return 0;
    }

    let mut c_size = unsafe {
        (seams.entropy_compress)(
            state.seq_store,
            ptr::addr_of!((*prev_c_block).entropy),
            ptr::addr_of_mut!((*next_c_block).entropy),
            state.strategy,
            state.disable_literal_compression,
            dst,
            dst_capacity,
            src_size,
            state.tmp_workspace,
            state.tmp_wksp_size,
            state.bmi2,
        )
    };

    if frame != 0
        && state.is_first_block == 0
        && c_size < RLE_MAX_LENGTH
        && unsafe { (seams.is_rle)(src.cast(), src_size) } != 0
    {
        /* Preserve the legacy decoder compatibility rule for the first frame
         * block: later repeated blocks may use the one-byte RLE form. */
        c_size = 1;
        unsafe {
            *dst.cast::<u8>() = *src.cast::<u8>();
        }
    }

    if !ERR_isError(c_size) && c_size > 1 {
        unsafe { (seams.confirm)(state.prev_c_block, state.next_c_block) };
    }

    let prev_c_block = unsafe { *state.prev_c_block };
    if prev_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    if unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode } == FSE_REPEAT_VALID {
        unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode = FSE_REPEAT_CHECK };
    }

    c_size
}

unsafe fn compress_block_internal_after_build_body_with(
    state: &ZSTD_rust_blockInternalState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    frame: c_uint,
    bss: c_int,
    seams: SingleBlockSeams,
) -> usize {
    if bss == ZSTD_BSS_NO_COMPRESS {
        if state.seq_collector.is_null() || state.prev_c_block.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        if unsafe { (*state.seq_collector).collectSequences } != 0 {
            return ERROR(ZstdErrorCode::SequenceProducerFailed);
        }
        let prev_c_block = unsafe { *state.prev_c_block };
        if prev_c_block.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        if unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode } == FSE_REPEAT_VALID {
            unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode = FSE_REPEAT_CHECK };
        }
        return 0;
    }
    if bss != ZSTD_BSS_COMPRESS {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_block_internal_body_with(state, dst, dst_capacity, src, src_size, frame, seams)
    }
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressBlockInternal(
    state: *const ZSTD_rust_blockInternalState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    frame: c_uint,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_block_internal_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            src_size,
            frame,
            SingleBlockSeams::production(),
        )
    }
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressBlockInternalAfterBuild(
    state: *const ZSTD_rust_blockInternalState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    frame: c_uint,
    bss: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_block_internal_after_build_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            src_size,
            frame,
            bss,
            SingleBlockSeams::production(),
        )
    }
}

#[inline]
fn sequence_block_action(
    is_first_block: c_int,
    maybe_rle: c_int,
    is_rle: c_int,
    compressed_size: usize,
) -> SequenceBlockAction {
    if is_first_block == 0 && maybe_rle != 0 && is_rle != 0 {
        return SequenceBlockAction::Rle;
    }
    match compressed_size {
        0 => SequenceBlockAction::Raw,
        1 => SequenceBlockAction::Rle,
        _ => SequenceBlockAction::Compressed,
    }
}

#[inline]
fn target_c_block_size_action(
    bss: c_int,
    is_first_block: c_int,
    maybe_rle: c_int,
    is_rle: c_int,
    c_size: usize,
    src_size: usize,
    strategy: c_int,
) -> TargetCBlockAction {
    if bss != ZSTD_TARGET_CBLOCK_BSS_COMPRESS {
        return TargetCBlockAction::Raw;
    }
    if is_first_block == 0 && maybe_rle != 0 && is_rle != 0 {
        return TargetCBlockAction::Rle;
    }
    if c_size == 0 || c_size == ERROR(ZstdErrorCode::DstSizeTooSmall) {
        return TargetCBlockAction::Raw;
    }
    if ERR_isError(c_size) {
        return TargetCBlockAction::Error;
    }

    let max_c_size = src_size.wrapping_sub(min_gain(src_size, strategy));
    if c_size < max_c_size.wrapping_add(ZSTD_BLOCK_HEADER_SIZE) {
        TargetCBlockAction::Compressed
    } else {
        TargetCBlockAction::Raw
    }
}

type TargetCBlockSuperBlockFn = unsafe extern "C" fn(
    *const c_void,
    *const c_void,
    *mut c_void,
    c_int,
    c_int,
    *mut c_void,
    usize,
    c_int,
    c_uint,
    usize,
    *mut c_void,
    usize,
    *const c_void,
    usize,
    c_uint,
) -> usize;

/// Rust implementation of `ZSTD_compressBlock_targetCBlockSize_body()`.
///
/// The C caller has already built the sequence store.  This function owns
/// only the RLE/superblock/raw decision and leaves context construction,
/// matchfinder state, frame progress, and outer repeat-mode cleanup in C.
#[allow(clippy::too_many_arguments)]
unsafe fn compress_block_target_c_block_size_body_with(
    state: &ZSTD_rust_targetCBlockSizeState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    bss: c_int,
    last_block: c_uint,
    compress_super_block: TargetCBlockSuperBlockFn,
) -> usize {
    if state.seq_store.is_null() || state.prev_c_block.is_null() || state.next_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let prev_c_block = unsafe { *state.prev_c_block };
    let next_c_block = unsafe { *state.next_c_block };
    if prev_c_block.is_null() || next_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let is_compress = bss == ZSTD_TARGET_CBLOCK_BSS_COMPRESS;
    let (maybe_rle, is_rle) = if is_compress {
        let maybe_rle = unsafe { ZSTD_rust_maybeRLE(state.seq_store) };
        let is_rle = unsafe { ZSTD_rust_isRLE(src.cast(), src_size) };
        (maybe_rle, is_rle)
    } else {
        (0, 0)
    };

    let action = target_c_block_size_action(
        bss,
        state.is_first_block,
        maybe_rle,
        is_rle,
        0,
        src_size,
        state.strategy,
    );
    if action == TargetCBlockAction::Rle {
        return unsafe {
            ZSTD_rust_rleCompressBlock(dst, dst_capacity, *src.cast::<u8>(), src_size, last_block)
        };
    }

    if is_compress {
        /* The superblock result is not bounded by ZSTD_compressBound().  The
         * policy helper therefore falls back to a raw block for zero,
         * dstSize_tooSmall, or an expansion beyond blockBound(srcSize). */
        let c_size = unsafe {
            compress_super_block(
                state.seq_store.cast(),
                prev_c_block.cast(),
                next_c_block.cast(),
                state.strategy,
                state.disable_literal_compression,
                state.tmp_workspace,
                state.tmp_wksp_size,
                state.bmi2,
                state.window_log,
                state.target_c_block_size,
                dst,
                dst_capacity,
                src,
                src_size,
                last_block,
            )
        };
        let action = target_c_block_size_action(
            bss,
            state.is_first_block,
            0,
            0,
            c_size,
            src_size,
            state.strategy,
        );
        if action == TargetCBlockAction::Error {
            return c_size;
        }
        if action == TargetCBlockAction::Compressed {
            unsafe {
                ZSTD_rust_confirmRepcodesAndEntropyTables(state.prev_c_block, state.next_c_block);
            }
            return c_size;
        }
    }

    unsafe { ZSTD_rust_noCompressBlock(dst, dst_capacity, src, src_size, last_block) }
}

unsafe fn compress_block_target_c_block_size_after_build_body_with(
    state: &ZSTD_rust_targetCBlockSizeState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    bss: c_int,
    last_block: c_uint,
    compress_super_block: TargetCBlockSuperBlockFn,
) -> usize {
    if bss != ZSTD_BSS_COMPRESS && bss != ZSTD_BSS_NO_COMPRESS {
        return ERROR(ZstdErrorCode::Generic);
    }
    let c_size = unsafe {
        compress_block_target_c_block_size_body_with(
            state,
            dst,
            dst_capacity,
            src,
            src_size,
            bss,
            last_block,
            compress_super_block,
        )
    };
    if ERR_isError(c_size) {
        return c_size;
    }
    if state.prev_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let prev_c_block = unsafe { *state.prev_c_block };
    if prev_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    if unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode } == FSE_REPEAT_VALID {
        unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode = FSE_REPEAT_CHECK };
    }
    c_size
}

/// C ABI entry point for the target-sized block body.  The public and outer
/// block APIs remain C-owned; this is only the body after `ZSTD_buildSeqStore`.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressBlockTargetCBlockSize(
    state: *const ZSTD_rust_targetCBlockSizeState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    bss: c_int,
    last_block: c_uint,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_block_target_c_block_size_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            src_size,
            bss,
            last_block,
            ZSTD_rust_compressSuperBlock,
        )
    }
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressBlockTargetCBlockSizeAfterBuild(
    state: *const ZSTD_rust_targetCBlockSizeState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    bss: c_int,
    last_block: c_uint,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_block_target_c_block_size_after_build_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            src_size,
            bss,
            last_block,
            ZSTD_rust_compressSuperBlock,
        )
    }
}

/// Rust implementation of `ZSTD_compressSeqStore_singleBlock`.
///
/// The C caller still owns sequence-store construction, split-block control,
/// and the private compression context.  This body owns the exact block
/// decision and the associated state transitions after the sequence store is
/// ready.
#[allow(clippy::too_many_arguments)]
unsafe fn compress_seq_store_single_block_body_with(
    state: &ZSTD_rust_seqStoreSingleBlockState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    last_block: c_uint,
    is_partition: c_uint,
    seams: SingleBlockSeams,
) -> usize {
    const RLE_MAX_LENGTH: usize = 25;

    if state.seq_store.is_null()
        || state.d_rep.is_null()
        || state.c_rep.is_null()
        || state.prev_c_block.is_null()
        || state.next_c_block.is_null()
        || state.seq_collector.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    let prev_c_block = unsafe { *state.prev_c_block };
    let next_c_block = unsafe { *state.next_c_block };
    if prev_c_block.is_null() || next_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    /* Preserve the decompression-side history for raw/RLE output and for the
     * sequence collector, exactly as the original C body does. */
    let mut d_rep_original = [0u32; ZSTD_REP_NUM];
    unsafe {
        ptr::copy_nonoverlapping(state.d_rep, d_rep_original.as_mut_ptr(), ZSTD_REP_NUM);
    }

    if is_partition != 0 {
        let seq_store = unsafe { &*state.seq_store };
        let nb_seq = unsafe { seq_store.sequences.offset_from(seq_store.sequencesStart) } as c_uint;
        unsafe {
            (seams.resolve_off_codes)(state.d_rep, state.c_rep, state.seq_store, nb_seq);
        }
    }

    if dst_capacity < ZSTD_BLOCK_HEADER_SIZE {
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }

    let op = dst.cast::<u8>();
    let ip = src.cast::<u8>();
    let mut compressed_sequences_size = unsafe {
        (seams.entropy_compress)(
            state.seq_store,
            ptr::addr_of!((*prev_c_block).entropy),
            ptr::addr_of_mut!((*next_c_block).entropy),
            state.strategy,
            state.disable_literal_compression,
            op.add(ZSTD_BLOCK_HEADER_SIZE).cast(),
            dst_capacity - ZSTD_BLOCK_HEADER_SIZE,
            src_size,
            state.tmp_workspace,
            state.tmp_wksp_size,
            state.bmi2,
        )
    };
    if ERR_isError(compressed_sequences_size) {
        return compressed_sequences_size;
    }

    if state.is_first_block == 0
        && compressed_sequences_size < RLE_MAX_LENGTH
        && unsafe { (seams.is_rle)(ip, src_size) } != 0
    {
        /* Do not emit the first frame block as RLE; this preserves the legacy
         * decoder compatibility rule in the original implementation. */
        compressed_sequences_size = 1;
    }

    /* Sequence collection is deliberately before block serialization and
     * returns without the outer repeat-mode cleanup, matching C. */
    if unsafe { (*state.seq_collector).collectSequences } != 0 {
        let result = unsafe {
            (seams.copy_sequences)(
                state.seq_collector,
                state.seq_store,
                d_rep_original.as_ptr(),
            )
        };
        if ERR_isError(result) {
            return result;
        }
        unsafe { (seams.confirm)(state.prev_c_block, state.next_c_block) };
        return 0;
    }

    let c_size = if compressed_sequences_size == 0 {
        let c_size = unsafe { (seams.raw)(dst, dst_capacity, src, src_size, last_block) };
        if ERR_isError(c_size) {
            return c_size;
        }
        unsafe {
            ptr::copy_nonoverlapping(d_rep_original.as_ptr(), state.d_rep, ZSTD_REP_NUM);
        }
        c_size
    } else if compressed_sequences_size == 1 {
        let c_size = unsafe { (seams.rle)(dst, dst_capacity, *ip, src_size, last_block) };
        if ERR_isError(c_size) {
            return c_size;
        }
        unsafe {
            ptr::copy_nonoverlapping(d_rep_original.as_ptr(), state.d_rep, ZSTD_REP_NUM);
        }
        c_size
    } else {
        unsafe { (seams.confirm)(state.prev_c_block, state.next_c_block) };
        unsafe {
            (seams.write_header)(dst, compressed_sequences_size, src_size, last_block);
        }
        ZSTD_BLOCK_HEADER_SIZE.wrapping_add(compressed_sequences_size)
    };

    let prev_c_block = unsafe { *state.prev_c_block };
    if unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode } == 2 {
        unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode = 1 };
    }

    c_size
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressSeqStoreSingleBlock(
    state: *const ZSTD_rust_seqStoreSingleBlockState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    last_block: c_uint,
    is_partition: c_uint,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_seq_store_single_block_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            src_size,
            last_block,
            is_partition,
            SingleBlockSeams::production(),
        )
    }
}

#[inline]
fn split_single_block_state(
    split_state: &ZSTD_rust_splitBlockState,
    seq_store: *const SeqStore_t,
    d_rep: &mut [u32; ZSTD_REP_NUM],
    c_rep: &mut [u32; ZSTD_REP_NUM],
) -> ZSTD_rust_seqStoreSingleBlockState {
    ZSTD_rust_seqStoreSingleBlockState {
        seq_store,
        d_rep: d_rep.as_mut_ptr(),
        c_rep: c_rep.as_mut_ptr(),
        prev_c_block: split_state.prev_c_block,
        next_c_block: split_state.next_c_block,
        tmp_workspace: split_state.tmp_workspace,
        tmp_wksp_size: split_state.tmp_wksp_size,
        seq_collector: split_state.seq_collector,
        strategy: split_state.strategy,
        disable_literal_compression: split_state.disable_literal_compression,
        bmi2: split_state.bmi2,
        is_first_block: split_state.is_first_block,
    }
}

/// Rust implementation of the post-split partition loop.
///
/// C retains the private `ZSTD_CCtx` and block-split storage; Rust receives
/// projected estimator inputs alongside the sequence-store views and owns the
/// partition accounting, repcode simulation, and block emission.
#[allow(clippy::too_many_arguments)]
unsafe fn compress_block_split_body_with(
    state: &ZSTD_rust_splitBlockState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    block_size: usize,
    last_block: c_uint,
    num_splits: usize,
    seams: SingleBlockSeams,
) -> usize {
    if state.seq_store.is_null()
        || state.partitions.is_null()
        || state.next_seq_store.is_null()
        || state.curr_seq_store.is_null()
        || state.prev_c_block.is_null()
        || state.next_c_block.is_null()
        || state.seq_collector.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    let prev_c_block = unsafe { *state.prev_c_block };
    let next_c_block = unsafe { *state.next_c_block };
    if prev_c_block.is_null() || next_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    /* cRep and dRep start from the preceding block and diverge only when a
     * partition is emitted as raw or RLE. */
    let mut d_rep = [0u32; ZSTD_REP_NUM];
    unsafe {
        ptr::copy_nonoverlapping(
            (*prev_c_block).rep.as_ptr(),
            d_rep.as_mut_ptr(),
            ZSTD_REP_NUM,
        );
    }
    let mut c_rep = d_rep;
    unsafe {
        ptr::write_bytes(
            state.next_seq_store.cast::<u8>(),
            0,
            size_of::<SeqStore_t>(),
        );
    }

    if num_splits == 0 {
        let single_state = split_single_block_state(state, state.seq_store, &mut d_rep, &mut c_rep);
        let c_size = unsafe {
            compress_seq_store_single_block_body_with(
                &single_state,
                dst,
                dst_capacity,
                src,
                block_size,
                last_block,
                0,
                seams,
            )
        };
        debug_assert!(state.block_size_max <= ZSTD_BLOCKSIZE_MAX);
        debug_assert!(
            c_size <= state.block_size_max.wrapping_add(ZSTD_BLOCK_HEADER_SIZE)
                || ERR_isError(c_size)
        );
        return c_size;
    }

    unsafe {
        ZSTD_rust_deriveSeqStoreChunk(
            state.curr_seq_store,
            state.seq_store,
            0,
            *state.partitions as usize,
        );
    }

    let mut c_size = 0usize;
    let mut src_bytes_total = 0usize;
    let mut ip = src.cast::<u8>();
    let mut op = dst.cast::<u8>();
    let mut remaining_capacity = dst_capacity;

    for i in 0..=num_splits {
        let last_partition = i == num_splits;
        let mut last_block_entire_src = 0;
        let partition_seq_store = state.curr_seq_store as *const SeqStore_t;
        let partition_bytes = unsafe {
            ZSTD_rust_countSeqStoreLiteralsBytes(partition_seq_store)
                .wrapping_add(ZSTD_rust_countSeqStoreMatchBytes(partition_seq_store))
        };
        src_bytes_total = src_bytes_total.wrapping_add(partition_bytes);
        let src_bytes = if last_partition {
            last_block_entire_src = last_block;
            partition_bytes.wrapping_add(block_size.wrapping_sub(src_bytes_total))
        } else {
            unsafe {
                ZSTD_rust_deriveSeqStoreChunk(
                    state.next_seq_store,
                    state.seq_store,
                    *state.partitions.add(i) as usize,
                    *state.partitions.add(i + 1) as usize,
                );
            }
            partition_bytes
        };

        let single_state =
            split_single_block_state(state, partition_seq_store, &mut d_rep, &mut c_rep);
        let c_size_chunk = unsafe {
            compress_seq_store_single_block_body_with(
                &single_state,
                op.cast(),
                remaining_capacity,
                ip.cast(),
                src_bytes,
                last_block_entire_src,
                1,
                seams,
            )
        };
        if ERR_isError(c_size_chunk) {
            return c_size_chunk;
        }

        unsafe {
            ip = ip.add(src_bytes);
            op = op.add(c_size_chunk);
        }
        remaining_capacity = remaining_capacity.wrapping_sub(c_size_chunk);
        c_size = c_size.wrapping_add(c_size_chunk);
        unsafe {
            ptr::copy_nonoverlapping(state.next_seq_store, state.curr_seq_store, 1);
        }
        debug_assert!(c_size_chunk <= state.block_size_max.wrapping_add(ZSTD_BLOCK_HEADER_SIZE));
    }

    let final_prev_c_block = unsafe { *state.prev_c_block };
    if final_prev_c_block.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        ptr::copy_nonoverlapping(
            d_rep.as_ptr(),
            (*final_prev_c_block).rep.as_mut_ptr(),
            ZSTD_REP_NUM,
        );
    }
    c_size
}

unsafe fn compress_block_split_after_build_body_with(
    state: &ZSTD_rust_splitBlockState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    block_size: usize,
    last_block: c_uint,
    num_splits: usize,
    bss: c_int,
    seams: SingleBlockSeams,
) -> usize {
    if bss == ZSTD_BSS_NO_COMPRESS {
        if state.seq_collector.is_null() || state.prev_c_block.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        if unsafe { (*state.seq_collector).collectSequences } != 0 {
            return ERROR(ZstdErrorCode::SequenceProducerFailed);
        }
        let prev_c_block = unsafe { *state.prev_c_block };
        if prev_c_block.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        if unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode } == FSE_REPEAT_VALID {
            unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode = FSE_REPEAT_CHECK };
        }
        return unsafe {
            ZSTD_rust_noCompressBlock(dst, dst_capacity, src, block_size, last_block)
        };
    }
    if bss != ZSTD_BSS_COMPRESS {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_block_split_body_with(
            state,
            dst,
            dst_capacity,
            src,
            block_size,
            last_block,
            num_splits,
            seams,
        )
    }
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressBlockSplit(
    state: *const ZSTD_rust_splitBlockState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    block_size: usize,
    last_block: c_uint,
    num_splits: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_block_split_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            block_size,
            last_block,
            num_splits,
            SingleBlockSeams::production(),
        )
    }
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressBlockSplitAfterBuild(
    state: *const ZSTD_rust_splitBlockState,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    block_size: usize,
    last_block: c_uint,
    num_splits: usize,
    bss: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    unsafe {
        compress_block_split_after_build_body_with(
            &*state,
            dst,
            dst_capacity,
            src,
            block_size,
            last_block,
            num_splits,
            bss,
            SingleBlockSeams::production(),
        )
    }
}

unsafe fn store_converted_sequence(
    seq_store: &mut SeqStore_t,
    lit_length: u32,
    off_base: u32,
    match_length: u32,
) -> bool {
    let sequence_index = unsafe { seq_store.sequences.offset_from(seq_store.sequencesStart) };
    if sequence_index < 0 || sequence_index as usize >= seq_store.maxNbSeq {
        return false;
    }
    let ml_base = match (match_length as usize).checked_sub(MINMATCH) {
        Some(value) => value,
        None => return false,
    };

    if lit_length as usize > u16::MAX as usize {
        if seq_store.longLengthType != 0 {
            return false;
        }
        seq_store.longLengthType = ZSTD_LLT_LITERAL_LENGTH;
        seq_store.longLengthPos = sequence_index as u32;
    }
    if ml_base > u16::MAX as usize {
        if seq_store.longLengthType != 0 {
            return false;
        }
        seq_store.longLengthType = ZSTD_LLT_MATCH_LENGTH;
        seq_store.longLengthPos = sequence_index as u32;
    }

    unsafe {
        (*seq_store.sequences).litLength = lit_length as u16;
        (*seq_store.sequences).offBase = off_base;
        (*seq_store.sequences).mlBase = ml_base as u16;
        seq_store.sequences = seq_store.sequences.add(1);
    }
    true
}

unsafe fn convert_block_sequences_body_with(
    state: &ZSTD_rust_convertBlockSequencesState,
    in_seqs: *const ZSTD_Sequence,
    nb_sequences: usize,
    repcode_resolution: c_int,
) -> usize {
    if state.seq_store.is_null()
        || state.prev_c_block.is_null()
        || state.next_c_block.is_null()
        || in_seqs.is_null()
        || nb_sequences == 0
    {
        return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
    }

    let seq_store = unsafe { &mut *state.seq_store };
    if nb_sequences >= seq_store.maxNbSeq {
        return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
    }
    let delimiter = unsafe { *in_seqs.add(nb_sequences - 1) };
    if delimiter.matchLength != 0 || delimiter.offset != 0 {
        return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
    }

    let prev_c_block = unsafe { *state.prev_c_block };
    let next_c_block = unsafe { *state.next_c_block };
    if prev_c_block.is_null() || next_c_block.is_null() {
        return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
    }

    let mut updated_repcodes = [0u32; ZSTD_REP_NUM];
    unsafe {
        ptr::copy_nonoverlapping(
            (*prev_c_block).rep.as_ptr(),
            updated_repcodes.as_mut_ptr(),
            ZSTD_REP_NUM,
        );
    }

    if repcode_resolution == 0 {
        let full_sequence_count = nb_sequences - 1;
        let long_length = unsafe {
            ZSTD_rust_convertSequencesNoRepcodes(
                seq_store.sequencesStart,
                in_seqs,
                full_sequence_count,
            )
        };
        if long_length != 0 {
            if seq_store.longLengthType != 0 {
                return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
            }
            if long_length <= full_sequence_count {
                seq_store.longLengthType = ZSTD_LLT_MATCH_LENGTH;
                seq_store.longLengthPos = (long_length - 1) as u32;
            } else if long_length <= full_sequence_count.saturating_mul(2) {
                seq_store.longLengthType = ZSTD_LLT_LITERAL_LENGTH;
                seq_store.longLengthPos = (long_length - nb_sequences) as u32;
            } else {
                return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
            }
        }
        seq_store.sequences = unsafe { seq_store.sequencesStart.add(full_sequence_count) };

        if nb_sequences > 1 {
            let rep = &mut updated_repcodes;
            if nb_sequences >= 4 {
                let last_seq_idx = nb_sequences - 2;
                rep[2] = unsafe { (*in_seqs.add(last_seq_idx - 2)).offset };
                rep[1] = unsafe { (*in_seqs.add(last_seq_idx - 1)).offset };
                rep[0] = unsafe { (*in_seqs.add(last_seq_idx)).offset };
            } else if nb_sequences == 3 {
                rep[2] = rep[0];
                rep[1] = unsafe { (*in_seqs).offset };
                rep[0] = unsafe { (*in_seqs.add(1)).offset };
            } else {
                rep[2] = rep[1];
                rep[1] = rep[0];
                rep[0] = unsafe { (*in_seqs).offset };
            }
        }
    } else {
        for index in 0..(nb_sequences - 1) {
            let sequence = unsafe { *in_seqs.add(index) };
            let ll0 = sequence.litLength == 0;
            let off_base = unsafe {
                ZSTD_rust_finalizeOffBase(
                    sequence.offset,
                    updated_repcodes.as_ptr(),
                    u32::from(ll0),
                )
            };
            if !unsafe {
                store_converted_sequence(
                    seq_store,
                    sequence.litLength,
                    off_base,
                    sequence.matchLength,
                )
            } {
                return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
            }
            update_rep(&mut updated_repcodes, off_base, ll0);
        }
    }

    unsafe {
        ptr::copy_nonoverlapping(
            updated_repcodes.as_ptr(),
            (*next_c_block).rep.as_mut_ptr(),
            ZSTD_REP_NUM,
        );
    }
    0
}

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_convertBlockSequences(
    state: *const ZSTD_rust_convertBlockSequencesState,
    in_seqs: *const ZSTD_Sequence,
    nb_sequences: usize,
    repcode_resolution: c_int,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
    }
    unsafe { convert_block_sequences_body_with(&*state, in_seqs, nb_sequences, repcode_resolution) }
}

/// Select the strategy used by the simple compression entry points.
///
/// This is the Rust equivalent of the strategy portion of
/// `ZSTD_getParams_internal(..., ZSTD_cpm_noAttachDict)`: use the actual
/// source size for table selection, then apply the ordinary automatic
/// parameter adjustment before dispatching to the Rust or C frame path.
#[no_mangle]
pub extern "C" fn ZSTD_rust_compressCCtxStrategy(
    src_size: usize,
    compression_level: c_int,
) -> c_int {
    let cparams = ZSTD_rust_params_selectCParams(
        compression_level,
        src_size as u64,
        0,
        ZSTD_RUST_CPM_NO_ATTACH_DICT,
    );
    ZSTD_rust_params_adjustCParams(
        cparams,
        src_size as u64,
        0,
        ZSTD_RUST_CPM_NO_ATTACH_DICT,
        ZSTD_RUST_PS_AUTO,
    )
    .strategy
}

/// Classify the target-sized block policy without crossing the C context ABI.
///
/// C calls this once before the superblock attempt to classify the RLE
/// precondition, then again with the superblock result and zero RLE flags.
#[no_mangle]
pub extern "C" fn ZSTD_rust_targetCBlockSizeAction(
    bss: c_int,
    is_first_block: c_int,
    maybe_rle: c_int,
    is_rle: c_int,
    c_size: usize,
    src_size: usize,
    strategy: c_int,
) -> c_int {
    target_c_block_size_action(
        bss,
        is_first_block,
        maybe_rle,
        is_rle,
        c_size,
        src_size,
        strategy,
    ) as c_int
}

#[repr(C)]
pub struct ZSTD_inBuffer {
    pub src: *const c_void,
    pub size: usize,
    pub pos: usize,
}

#[repr(C)]
pub struct ZSTD_outBuffer {
    pub dst: *mut c_void,
    pub size: usize,
    pub pos: usize,
}

#[no_mangle]
pub extern "C" fn ZSTD_rust_inBufferForEndFlush(
    in_buffer_mode: c_int,
    expected_src: *const c_void,
    expected_size: usize,
    expected_pos: usize,
) -> ZSTD_inBuffer {
    if in_buffer_mode == ZSTD_BM_STABLE {
        ZSTD_inBuffer {
            src: expected_src,
            size: expected_size,
            pos: expected_pos,
        }
    } else {
        ZSTD_inBuffer {
            src: ptr::null(),
            size: 0,
            pos: 0,
        }
    }
}

#[inline]
fn end_stream_remaining(
    remaining_to_flush: usize,
    frame_ended: c_int,
    checksum_flag: c_int,
) -> usize {
    if frame_ended != 0 {
        return remaining_to_flush;
    }

    remaining_to_flush
        .wrapping_add(ZSTD_BLOCK_HEADER_SIZE)
        .wrapping_add((checksum_flag as usize).wrapping_mul(4))
}

/// Estimate single-threaded end-stream output without crossing C context state.
#[no_mangle]
pub extern "C" fn ZSTD_rust_endStreamRemaining(
    remaining_to_flush: usize,
    frame_ended: c_int,
    checksum_flag: c_int,
) -> usize {
    end_stream_remaining(remaining_to_flush, frame_ended, checksum_flag)
}

#[inline]
fn check_buffer_stability(
    in_buffer_mode: c_int,
    out_buffer_mode: c_int,
    expected_in_src: *const c_void,
    expected_in_pos: usize,
    input_src: *const c_void,
    input_pos: usize,
    expected_out_buffer_size: usize,
    output_size: usize,
    output_pos: usize,
) -> usize {
    if in_buffer_mode == ZSTD_BM_STABLE
        && (expected_in_src != input_src || expected_in_pos != input_pos)
    {
        return ERROR(ZstdErrorCode::StabilityConditionNotRespected);
    }

    if out_buffer_mode == ZSTD_BM_STABLE
        && expected_out_buffer_size != output_size.wrapping_sub(output_pos)
    {
        return ERROR(ZstdErrorCode::StabilityConditionNotRespected);
    }

    0
}

/// Validate the stable input/output buffer expectations without crossing the
/// private `ZSTD_CCtx` layout into Rust. Raw pointers are compared only for
/// identity and are never dereferenced.
#[no_mangle]
pub extern "C" fn ZSTD_rust_checkBufferStability(
    in_buffer_mode: c_int,
    out_buffer_mode: c_int,
    expected_in_src: *const c_void,
    expected_in_pos: usize,
    input_src: *const c_void,
    input_pos: usize,
    expected_out_buffer_size: usize,
    output_size: usize,
    output_pos: usize,
) -> usize {
    check_buffer_stability(
        in_buffer_mode,
        out_buffer_mode,
        expected_in_src,
        expected_in_pos,
        input_src,
        input_pos,
        expected_out_buffer_size,
        output_size,
        output_pos,
    )
}

#[inline]
unsafe fn set_buffer_expectations(
    in_buffer_mode: c_int,
    out_buffer_mode: c_int,
    expected_in_buffer: *mut ZSTD_inBuffer,
    expected_out_buffer_size: *mut usize,
    output: *const ZSTD_outBuffer,
    input: *const ZSTD_inBuffer,
) {
    if in_buffer_mode == ZSTD_BM_STABLE {
        unsafe {
            *expected_in_buffer = ptr::read(input);
        }
    }
    if out_buffer_mode == ZSTD_BM_STABLE {
        let output = unsafe { &*output };
        unsafe {
            *expected_out_buffer_size = output.size.wrapping_sub(output.pos);
        }
    }
}

/// Update the stable input/output expectations after a compression call.
///
/// C retains the private `ZSTD_CCtx` fields and passes only their projections;
/// Rust owns the buffer-mode policy and C-size arithmetic.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_setBufferExpectations(
    in_buffer_mode: c_int,
    out_buffer_mode: c_int,
    expected_in_buffer: *mut ZSTD_inBuffer,
    expected_out_buffer_size: *mut usize,
    output: *const ZSTD_outBuffer,
    input: *const ZSTD_inBuffer,
) {
    unsafe {
        set_buffer_expectations(
            in_buffer_mode,
            out_buffer_mode,
            expected_in_buffer,
            expected_out_buffer_size,
            output,
            input,
        );
    }
}

#[inline]
fn select_sequence_copier(mode: c_int) -> c_int {
    debug_assert!(
        (ZSTD_SF_NO_BLOCK_DELIMITERS..=ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS).contains(&mode)
    );
    if mode == ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS {
        ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS
    } else {
        debug_assert_eq!(mode, ZSTD_SF_NO_BLOCK_DELIMITERS);
        ZSTD_SF_NO_BLOCK_DELIMITERS
    }
}

/// Select the C-side sequence transfer policy without crossing private
/// function pointers through the Rust ABI. Invalid values retain the C
/// release fallback to the no-delimiter policy after debug validation.
#[no_mangle]
pub extern "C" fn ZSTD_rust_selectSequenceCopier(mode: c_int) -> c_int {
    select_sequence_copier(mode)
}

/* HUF_WORKSPACE_SIZE + (MaxSeq + 2) * sizeof(unsigned), rounded up.  The
 * superblock leaf also accepts the larger pre-split workspace, so a fixed
 * 16 KiB buffer is sufficient for this first non-splitting path on both
 * supported pointer widths. */
const TMP_WORKSPACE_SIZE: usize = 16 << 10;

#[inline]
fn update_frame_progression(
    consumed_src_size: &mut u64,
    produced_c_size: &mut u64,
    pledged_src_size_plus_one: u64,
    src_size: usize,
    c_size: usize,
    frame_header_size: usize,
) -> bool {
    *consumed_src_size = consumed_src_size.wrapping_add(src_size as u64);
    *produced_c_size = produced_c_size.wrapping_add(c_size.wrapping_add(frame_header_size) as u64);

    pledged_src_size_plus_one != 0 && consumed_src_size.wrapping_add(1) > pledged_src_size_plus_one
}

/// Update C-owned frame counters after successful compression.
///
/// A zero pledge means that the source size is unknown.  C keeps the
/// diagnostic that accompanies a nonzero overrun result.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_updateFrameProgression(
    consumed_src_size: *mut u64,
    produced_c_size: *mut u64,
    pledged_src_size_plus_one: u64,
    src_size: usize,
    c_size: usize,
    frame_header_size: usize,
) -> c_int {
    let consumed_src_size = unsafe { &mut *consumed_src_size };
    let produced_c_size = unsafe { &mut *produced_c_size };
    update_frame_progression(
        consumed_src_size,
        produced_c_size,
        pledged_src_size_plus_one,
        src_size,
        c_size,
        frame_header_size,
    ) as c_int
}

/// ABI-compatible representation of `ZSTD_frameProgression` from `zstd.h`.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_frameProgression {
    pub ingested: u64,
    pub consumed: u64,
    pub produced: u64,
    pub flushed: u64,
    pub currentJobID: c_uint,
    pub nbActiveWorkers: c_uint,
}

#[inline]
fn frame_progression(
    consumed_src_size: u64,
    buffered: usize,
    produced_c_size: u64,
) -> ZSTD_frameProgression {
    ZSTD_frameProgression {
        // C's usual arithmetic conversions promote size_t to U64 before wrapping.
        ingested: consumed_src_size.wrapping_add(buffered as u64),
        consumed: consumed_src_size,
        produced: produced_c_size,
        flushed: produced_c_size,
        currentJobID: 0,
        nbActiveWorkers: 0,
    }
}

/// Construct single-threaded frame progression from C-owned scalar state.
#[no_mangle]
pub extern "C" fn ZSTD_rust_frameProgression(
    consumed_src_size: u64,
    buffered: usize,
    produced_c_size: u64,
) -> ZSTD_frameProgression {
    frame_progression(consumed_src_size, buffered, produced_c_size)
}

type ToFlushNowFn = unsafe extern "C" fn(*mut c_void) -> usize;

/// Explicit projection for the `ZSTD_toFlushNow` multithread policy.
///
/// Rust owns the worker-count branch; C retains the private CCtx and MT
/// context behind the callback.
#[repr(C)]
pub struct ZSTD_rust_toFlushNowState {
    callback_context: *mut c_void,
    nb_workers: c_int,
    to_flush_now: ToFlushNowFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_toFlushNowState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_toFlushNowState, nb_workers) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_toFlushNowState, to_flush_now) == 2 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_toFlushNowState>() == 3 * size_of::<usize>());
};

#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_toFlushNow(state: *const ZSTD_rust_toFlushNowState) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.nb_workers <= 0 {
        return 0;
    }
    unsafe { (state.to_flush_now)(state.callback_context) }
}

#[inline]
fn window_correct_overflow(curr: u32, cycle_log: u32, max_dist: u32) -> u32 {
    let cycle_size = 1u32.wrapping_shl(cycle_log);
    let cycle_mask = cycle_size.wrapping_sub(1);
    let current_cycle = curr & cycle_mask;
    let current_cycle_correction = if current_cycle < ZSTD_WINDOW_START_INDEX {
        cycle_size.max(ZSTD_WINDOW_START_INDEX)
    } else {
        0
    };
    let new_current = current_cycle
        .wrapping_add(current_cycle_correction)
        .wrapping_add(max_dist.max(cycle_size));
    curr.wrapping_sub(new_current)
}

/// Return the scalar correction for C's window-overflow state transition.
///
/// C retains pointer arithmetic, invariant checks, and all `ZSTD_window_t`
/// mutation.  This leaf owns only the U32 cycle arithmetic so its wrapping
/// behavior is explicit and independent of the host pointer width.
#[no_mangle]
pub extern "C" fn ZSTD_rust_windowCorrectOverflow(curr: u32, cycle_log: u32, max_dist: u32) -> u32 {
    window_correct_overflow(curr, cycle_log, max_dist)
}

#[inline]
fn window_can_overflow_correct(
    curr: u32,
    cycle_log: u32,
    max_dist: u32,
    loaded_dict_end: u32,
    nb_overflow_corrections: u32,
) -> bool {
    let cycle_size = 1u32.wrapping_shl(cycle_log);
    let min_index_to_overflow_correct = cycle_size
        .wrapping_add(max_dist.max(cycle_size))
        .wrapping_add(ZSTD_WINDOW_START_INDEX);
    let adjustment = nb_overflow_corrections.wrapping_add(1);
    let adjusted_index = min_index_to_overflow_correct
        .wrapping_mul(adjustment)
        .max(min_index_to_overflow_correct);
    let index_large_enough = curr > adjusted_index;
    let dictionary_invalidated = curr > max_dist.wrapping_add(loaded_dict_end);
    index_large_enough && dictionary_invalidated
}

/// Return whether the C-owned window state should enter overflow correction.
///
/// C retains both pointer subtractions and the `ZSTD_window_t` state. The
/// early-correction result is supplied as a scalar because it is based on the
/// block-start index, while `curr` is the block-end index used by the normal
/// current-limit fallback. The current limit and fuzzing policy are supplied
/// by C so their 32/64-bit and build-mode choices remain authoritative.
#[inline]
fn window_need_overflow_correction(
    curr: u32,
    can_overflow_correct: bool,
    current_max: u32,
    overflow_correct_frequently: bool,
) -> bool {
    (overflow_correct_frequently && can_overflow_correct) || curr > current_max
}

#[no_mangle]
pub extern "C" fn ZSTD_rust_windowCanOverflowCorrect(
    curr: u32,
    cycle_log: u32,
    max_dist: u32,
    loaded_dict_end: u32,
    nb_overflow_corrections: u32,
) -> u32 {
    window_can_overflow_correct(
        curr,
        cycle_log,
        max_dist,
        loaded_dict_end,
        nb_overflow_corrections,
    ) as u32
}

#[no_mangle]
pub extern "C" fn ZSTD_rust_windowNeedOverflowCorrection(
    curr: u32,
    can_overflow_correct: u32,
    current_max: u32,
    overflow_correct_frequently: c_int,
) -> u32 {
    window_need_overflow_correction(
        curr,
        can_overflow_correct != 0,
        current_max,
        overflow_correct_frequently != 0,
    ) as u32
}

type OverflowNeedCorrectionFn =
    unsafe extern "C" fn(*mut c_void, *const c_void, *const c_void) -> c_int;
type OverflowCorrectFn = unsafe extern "C" fn(*mut c_void, *const c_void) -> c_uint;
type OverflowCallbackFn = unsafe extern "C" fn(*mut c_void);
type OverflowReduceIndexFn = unsafe extern "C" fn(*mut c_void, c_uint);

/// Projection for the overflow-correction ordering around C-owned match state.
///
/// Rust owns the correction branch and callback order. C retains the window,
/// workspace, match tables, and dictionary pointers behind these callbacks.
#[repr(C)]
pub struct ZSTD_rust_overflowCorrectState {
    callback_context: *mut c_void,
    next_to_update: *mut c_uint,
    need_correction: Option<OverflowNeedCorrectionFn>,
    correct_overflow: Option<OverflowCorrectFn>,
    mark_tables_dirty: Option<OverflowCallbackFn>,
    reduce_index: Option<OverflowReduceIndexFn>,
    mark_tables_clean: Option<OverflowCallbackFn>,
    loaded_dict_end: *mut c_uint,
    dict_match_state: *mut *const c_void,
}

const _: () = {
    assert!(size_of::<OverflowNeedCorrectionFn>() == size_of::<usize>());
    assert!(size_of::<OverflowCorrectFn>() == size_of::<usize>());
    assert!(size_of::<OverflowCallbackFn>() == size_of::<usize>());
    assert!(size_of::<OverflowReduceIndexFn>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_overflowCorrectState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_overflowCorrectState, next_to_update) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_overflowCorrectState, need_correction) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_overflowCorrectState, correct_overflow) == 3 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_overflowCorrectState, mark_tables_dirty) == 4 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_overflowCorrectState, reduce_index) == 5 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_overflowCorrectState, mark_tables_clean) == 6 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_overflowCorrectState, loaded_dict_end) == 7 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_overflowCorrectState, dict_match_state) == size_of::<[usize; 8]>()
    );
    assert!(size_of::<ZSTD_rust_overflowCorrectState>() == size_of::<[usize; 9]>());
};

/// Apply one overflow correction while keeping all private codec state in C.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_overflowCorrectIfNeeded(
    state: *const ZSTD_rust_overflowCorrectState,
    src: *const c_void,
    src_end: *const c_void,
) {
    if state.is_null() {
        return;
    }
    let state = unsafe { &*state };
    if state.callback_context.is_null()
        || state.next_to_update.is_null()
        || state.loaded_dict_end.is_null()
        || state.dict_match_state.is_null()
    {
        return;
    }
    let (
        Some(need_correction),
        Some(correct_overflow),
        Some(mark_tables_dirty),
        Some(reduce_index),
        Some(mark_tables_clean),
    ) = (
        state.need_correction,
        state.correct_overflow,
        state.mark_tables_dirty,
        state.reduce_index,
        state.mark_tables_clean,
    )
    else {
        return;
    };

    unsafe {
        if need_correction(state.callback_context, src, src_end) == 0 {
            return;
        }
        let correction = correct_overflow(state.callback_context, src);
        mark_tables_dirty(state.callback_context);
        reduce_index(state.callback_context, correction);
        mark_tables_clean(state.callback_context);
        *state.next_to_update = (*state.next_to_update).saturating_sub(correction);
        *state.loaded_dict_end = 0;
        *state.dict_match_state = ptr::null();
    }
}

#[inline]
fn limit_next_to_update(curr: u32, next_to_update: u32) -> u32 {
    let const_gap = 384u32;
    let const_step = 192u32;
    if curr > next_to_update.wrapping_add(const_gap) {
        curr.wrapping_sub(const_step.min(curr.wrapping_sub(next_to_update).wrapping_sub(const_gap)))
    } else {
        next_to_update
    }
}

/// Limit a stale matchfinder update point after a very long match.
///
/// C computes the source index against its private window base; Rust owns the
/// wrapping U32 threshold and bounded catch-up arithmetic.
#[no_mangle]
pub extern "C" fn ZSTD_rust_limitNextToUpdate(curr: u32, next_to_update: u32) -> u32 {
    limit_next_to_update(curr, next_to_update)
}

#[inline]
fn next_input_size_hint(
    in_buffer_mode: c_int,
    block_size_max: usize,
    stable_in_not_consumed: usize,
    in_buff_target: usize,
    in_buff_pos: usize,
) -> usize {
    if in_buffer_mode == ZSTD_BM_STABLE {
        return block_size_max.wrapping_sub(stable_in_not_consumed);
    }

    let hint_in_size = in_buff_target.wrapping_sub(in_buff_pos);
    if hint_in_size == 0 {
        block_size_max
    } else {
        hint_in_size
    }
}

/// Return the next input size required by the C streaming state machine.
#[no_mangle]
pub extern "C" fn ZSTD_rust_nextInputSizeHint(
    in_buffer_mode: c_int,
    block_size_max: usize,
    stable_in_not_consumed: usize,
    in_buff_target: usize,
    in_buff_pos: usize,
) -> usize {
    next_input_size_hint(
        in_buffer_mode,
        block_size_max,
        stable_in_not_consumed,
        in_buff_target,
        in_buff_pos,
    )
}

type NextInputSizeHintMTorSTFn = unsafe extern "C" fn(*mut c_void) -> usize;

/// Projection for the MT-versus-single-thread input-hint dispatch.
///
/// Rust owns only the worker-count branch. The single-thread hint inputs are
/// scalar, while the MT context remains opaque behind its C callback.
#[repr(C)]
pub struct ZSTD_rust_nextInputSizeHintMTorSTState {
    block_size_max: usize,
    stable_in_not_consumed: usize,
    in_buff_target: usize,
    in_buff_pos: usize,
    nb_workers: c_int,
    in_buffer_mode: c_int,
    mt_context: *mut c_void,
    mt_next_input_size_hint: Option<NextInputSizeHintMTorSTFn>,
}

const _: () = {
    assert!(size_of::<NextInputSizeHintMTorSTFn>() == size_of::<usize>());
    assert!(size_of::<Option<NextInputSizeHintMTorSTFn>>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_nextInputSizeHintMTorSTState, block_size_max) == 0);
    assert!(
        offset_of!(
            ZSTD_rust_nextInputSizeHintMTorSTState,
            stable_in_not_consumed
        ) == size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_nextInputSizeHintMTorSTState, in_buff_target)
            == 2 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_nextInputSizeHintMTorSTState, in_buff_pos) == 3 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_nextInputSizeHintMTorSTState, nb_workers) == 4 * size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_nextInputSizeHintMTorSTState, in_buffer_mode)
            == 4 * size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_nextInputSizeHintMTorSTState, mt_context)
            == 4 * size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(
            ZSTD_rust_nextInputSizeHintMTorSTState,
            mt_next_input_size_hint
        ) == 4 * size_of::<usize>() + 2 * size_of::<c_int>() + size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_nextInputSizeHintMTorSTState>()
            == 4 * size_of::<usize>() + 2 * size_of::<c_int>() + 2 * size_of::<usize>()
    );
};

/// Select the MT or single-thread input-size hint without exposing the MT
/// context representation to Rust.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_nextInputSizeHintMTorST(
    state: *const ZSTD_rust_nextInputSizeHintMTorSTState,
) -> usize {
    let Some(state) = (unsafe { state.as_ref() }) else {
        return 0;
    };
    if state.nb_workers >= 1 {
        let Some(mt_next_input_size_hint) = state.mt_next_input_size_hint else {
            return 0;
        };
        return unsafe { mt_next_input_size_hint(state.mt_context) };
    }
    next_input_size_hint(
        state.in_buffer_mode,
        state.block_size_max,
        state.stable_in_not_consumed,
        state.in_buff_target,
        state.in_buff_pos,
    )
}

#[inline]
fn mt_next_input_size_hint(target_section_size: usize, in_buff_filled: usize) -> usize {
    let hint_in_size = target_section_size.wrapping_sub(in_buff_filled);
    if hint_in_size == 0 {
        target_section_size
    } else {
        hint_in_size
    }
}

/// Return the next input size required by the C multithreaded streaming state.
#[no_mangle]
pub extern "C" fn ZSTDMT_rust_nextInputSizeHint(
    target_section_size: usize,
    in_buff_filled: usize,
) -> usize {
    mt_next_input_size_hint(target_section_size, in_buff_filled)
}

#[inline]
fn mt_sizeof_cctx(
    mtctx_size: usize,
    factory_size: usize,
    buffer_pool_size: usize,
    jobs_size: usize,
    cctx_pool_size: usize,
    seq_pool_size: usize,
    cdict_size: usize,
    round_buff_size: usize,
) -> usize {
    mtctx_size
        .wrapping_add(factory_size)
        .wrapping_add(buffer_pool_size)
        .wrapping_add(jobs_size)
        .wrapping_add(cctx_pool_size)
        .wrapping_add(seq_pool_size)
        .wrapping_add(cdict_size)
        .wrapping_add(round_buff_size)
}

/// Aggregate C-owned multithreaded context size components with C `size_t`
/// wrapping semantics.
#[no_mangle]
pub extern "C" fn ZSTDMT_rust_sizeofCCtx(
    mtctx_size: usize,
    factory_size: usize,
    buffer_pool_size: usize,
    jobs_size: usize,
    cctx_pool_size: usize,
    seq_pool_size: usize,
    cdict_size: usize,
    round_buff_size: usize,
) -> usize {
    mt_sizeof_cctx(
        mtctx_size,
        factory_size,
        buffer_pool_size,
        jobs_size,
        cctx_pool_size,
        seq_pool_size,
        cdict_size,
        round_buff_size,
    )
}

#[inline]
fn bitmix(mut val: u64, len: u64) -> u64 {
    val ^= val.rotate_right(49) ^ val.rotate_right(24);
    val = val.wrapping_mul(0x9FB21C651E98DF25);
    val ^= (val >> 35).wrapping_add(len);
    val = val.wrapping_mul(0x9FB21C651E98DF25);
    val ^ (val >> 28)
}

#[inline]
fn advance_hash_salt(hash_salt: u64, hash_salt_entropy: u64) -> u64 {
    bitmix(hash_salt, 8) ^ bitmix(hash_salt_entropy, 4)
}

/// Advance the row-matchfinder salt without exposing C's private match state.
#[no_mangle]
pub extern "C" fn ZSTD_rust_advanceHashSalt(hash_salt: u64, hash_salt_entropy: u64) -> u64 {
    advance_hash_salt(hash_salt, hash_salt_entropy)
}

/// Advance a C-owned row-matchfinder salt in place while C retains the
/// private match-state layout.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_advanceHashSaltInPlace(
    hash_salt: *mut u64,
    hash_salt_entropy: u64,
) {
    debug_assert!(!hash_salt.is_null());
    unsafe {
        *hash_salt = advance_hash_salt(*hash_salt, hash_salt_entropy);
    }
}

#[inline]
fn index_too_close_to_max(next_src_base_offset: usize) -> bool {
    next_src_base_offset > ZSTD_CURRENT_MAX - ZSTD_INDEXOVERFLOW_MARGIN
}

/// Return whether a scalar C window offset is within the overflow margin.
#[no_mangle]
pub extern "C" fn ZSTD_indexTooCloseToMax(next_src_base_offset: usize) -> c_int {
    index_too_close_to_max(next_src_base_offset) as c_int
}

#[inline]
fn dict_too_big(loaded_dict_size: usize) -> bool {
    loaded_dict_size > ZSTD_CHUNKSIZE_MAX
}

/// Return whether a dictionary exceeds the maximum loadable chunk size.
#[no_mangle]
pub extern "C" fn ZSTD_dictTooBig(loaded_dict_size: usize) -> c_int {
    dict_too_big(loaded_dict_size) as c_int
}

type ResetMatchStateCallback = unsafe extern "C" fn(*mut c_void);
type ResetMatchStateSetPointer = unsafe extern "C" fn(*mut c_void, c_int, *mut c_void);
type ResetMatchStateReserve = unsafe extern "C" fn(*mut c_void, c_int, usize) -> *mut c_void;
type ResetMatchStateReserveFailed = unsafe extern "C" fn(*mut c_void) -> c_int;
type ResetMatchStateZero = unsafe extern "C" fn(*mut c_void, *mut c_void, usize);

const RESET_MATCH_RESERVE_TABLE: c_int = 0;
const RESET_MATCH_RESERVE_ALIGNED_INIT_ONCE: c_int = 1;
const RESET_MATCH_RESERVE_ALIGNED64: c_int = 2;

const RESET_MATCH_POINTER_HASH_TABLE: c_int = 0;
const RESET_MATCH_POINTER_CHAIN_TABLE: c_int = 1;
const RESET_MATCH_POINTER_HASH_TABLE3: c_int = 2;
const RESET_MATCH_POINTER_TAG_TABLE: c_int = 3;
const RESET_MATCH_POINTER_LIT_FREQ: c_int = 4;
const RESET_MATCH_POINTER_LIT_LENGTH_FREQ: c_int = 5;
const RESET_MATCH_POINTER_MATCH_LENGTH_FREQ: c_int = 6;
const RESET_MATCH_POINTER_OFF_CODE_FREQ: c_int = 7;
const RESET_MATCH_POINTER_MATCH_TABLE: c_int = 8;
const RESET_MATCH_POINTER_PRICE_TABLE: c_int = 9;

/// Private C layout pointers and callback seams for match-state reset.
///
/// Rust owns the reset policy and allocation order. C retains the workspace,
/// window, and private match-state pointer representations behind callbacks.
#[repr(C)]
pub struct ZSTD_rust_resetMatchStateState {
    callback_context: *mut c_void,
    c_params: ZSTD_compressionParameters,
    dedicated_dict_search: c_int,
    use_row_match_finder: c_int,
    comp_reset_policy: c_int,
    index_reset_policy: c_int,
    reset_target: c_int,
    hash_log3_max: c_uint,
    lit_freq_size: usize,
    lit_length_freq_size: usize,
    match_length_freq_size: usize,
    off_code_freq_size: usize,
    match_size: usize,
    optimal_size: usize,
    hash_log3: *mut c_uint,
    row_hash_log: *mut c_uint,
    hash_salt: *mut u64,
    lazy_skipping: *mut c_int,
    c_params_out: *mut ZSTD_compressionParameters,
    set_pointer: Option<ResetMatchStateSetPointer>,
    window_init: Option<ResetMatchStateCallback>,
    mark_tables_dirty: Option<ResetMatchStateCallback>,
    invalidate_match_state: Option<ResetMatchStateCallback>,
    clear_tables: Option<ResetMatchStateCallback>,
    clean_tables: Option<ResetMatchStateCallback>,
    advance_hash_salt: Option<ResetMatchStateCallback>,
    reserve: Option<ResetMatchStateReserve>,
    reserve_failed: Option<ResetMatchStateReserveFailed>,
    zero: Option<ResetMatchStateZero>,
}

const _: () = {
    assert!(size_of::<ResetMatchStateCallback>() == size_of::<usize>());
    assert!(size_of::<ResetMatchStateSetPointer>() == size_of::<usize>());
    assert!(size_of::<ResetMatchStateReserve>() == size_of::<usize>());
    assert!(size_of::<ResetMatchStateReserveFailed>() == size_of::<usize>());
    assert!(size_of::<ResetMatchStateZero>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetMatchStateState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_resetMatchStateState, c_params) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_resetMatchStateState, lit_freq_size)
            > offset_of!(ZSTD_rust_resetMatchStateState, hash_log3_max)
    );
    assert!(
        offset_of!(ZSTD_rust_resetMatchStateState, hash_log3)
            == offset_of!(ZSTD_rust_resetMatchStateState, optimal_size) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetMatchStateState, set_pointer)
            == offset_of!(ZSTD_rust_resetMatchStateState, c_params_out) + size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_resetMatchStateState>()
            == offset_of!(ZSTD_rust_resetMatchStateState, zero) + size_of::<usize>()
    );
};

#[inline]
fn reset_match_state_table_size(log: u32) -> Option<usize> {
    1usize.checked_shl(log)
}

/// Reset and allocate one private match-state projection.
///
/// The callback context deliberately remains opaque here. This keeps C's
/// workspace phases and match-state layout out of the Rust ABI while making
/// the policy/order independently testable.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_resetMatchState(
    state: *const ZSTD_rust_resetMatchStateState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let Some(set_pointer) = state.set_pointer else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(window_init) = state.window_init else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(mark_tables_dirty) = state.mark_tables_dirty else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(invalidate_match_state) = state.invalidate_match_state else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(clear_tables) = state.clear_tables else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(clean_tables) = state.clean_tables else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(advance_hash_salt) = state.advance_hash_salt else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(reserve) = state.reserve else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(reserve_failed) = state.reserve_failed else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(zero) = state.zero else {
        return ERROR(ZstdErrorCode::Generic);
    };
    if state.callback_context.is_null()
        || state.hash_log3.is_null()
        || state.row_hash_log.is_null()
        || state.hash_salt.is_null()
        || state.lazy_skipping.is_null()
        || state.c_params_out.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }
    if state.use_row_match_finder == ZSTD_RUST_PS_AUTO
        || !matches!(state.comp_reset_policy, 0..=1)
        || !matches!(state.index_reset_policy, 0..=1)
        || !matches!(state.reset_target, 0..=1)
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    let chain_size = if ZSTD_rust_params_allocateChainTable(
        state.c_params.strategy,
        state.use_row_match_finder,
        c_int::from(state.dedicated_dict_search != 0 && state.reset_target == 0),
    ) != 0
    {
        let Some(size) = reset_match_state_table_size(state.c_params.chainLog) else {
            return ERROR(ZstdErrorCode::Generic);
        };
        size
    } else {
        0
    };
    let Some(hash_size) = reset_match_state_table_size(state.c_params.hashLog) else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let hash_log3 = if state.reset_target == 1 && state.c_params.minMatch == 3 {
        state.hash_log3_max.min(state.c_params.windowLog)
    } else {
        0
    };
    let hash3_size = if hash_log3 == 0 {
        0
    } else {
        let Some(size) = reset_match_state_table_size(hash_log3) else {
            return ERROR(ZstdErrorCode::Generic);
        };
        size
    };

    if state.index_reset_policy == 1 {
        unsafe {
            window_init(state.callback_context);
            mark_tables_dirty(state.callback_context);
        }
    }

    unsafe {
        *state.hash_log3 = hash_log3;
        *state.lazy_skipping = 0;
        invalidate_match_state(state.callback_context);
        debug_assert_eq!(reserve_failed(state.callback_context), 0);
        clear_tables(state.callback_context);
    }

    unsafe {
        set_pointer(
            state.callback_context,
            RESET_MATCH_POINTER_HASH_TABLE,
            reserve(
                state.callback_context,
                RESET_MATCH_RESERVE_TABLE,
                hash_size.wrapping_mul(size_of::<c_uint>()),
            ),
        );
        set_pointer(
            state.callback_context,
            RESET_MATCH_POINTER_CHAIN_TABLE,
            reserve(
                state.callback_context,
                RESET_MATCH_RESERVE_TABLE,
                chain_size.wrapping_mul(size_of::<c_uint>()),
            ),
        );
        set_pointer(
            state.callback_context,
            RESET_MATCH_POINTER_HASH_TABLE3,
            reserve(
                state.callback_context,
                RESET_MATCH_RESERVE_TABLE,
                hash3_size.wrapping_mul(size_of::<c_uint>()),
            ),
        );
    }
    if unsafe { reserve_failed(state.callback_context) } != 0 {
        return ERROR(ZstdErrorCode::MemoryAllocation);
    }

    if state.comp_reset_policy != 1 {
        unsafe { clean_tables(state.callback_context) };
    }

    if ZSTD_rust_params_rowMatchFinderUsed(state.c_params.strategy, state.use_row_match_finder) != 0
    {
        if state.reset_target == 1 {
            let tag_table = unsafe {
                reserve(
                    state.callback_context,
                    RESET_MATCH_RESERVE_ALIGNED_INIT_ONCE,
                    hash_size,
                )
            };
            unsafe {
                set_pointer(
                    state.callback_context,
                    RESET_MATCH_POINTER_TAG_TABLE,
                    tag_table,
                );
                advance_hash_salt(state.callback_context);
            }
        } else {
            let tag_table = unsafe {
                reserve(
                    state.callback_context,
                    RESET_MATCH_RESERVE_ALIGNED64,
                    hash_size,
                )
            };
            unsafe {
                set_pointer(
                    state.callback_context,
                    RESET_MATCH_POINTER_TAG_TABLE,
                    tag_table,
                );
            }
            if unsafe { reserve_failed(state.callback_context) } != 0 {
                return ERROR(ZstdErrorCode::MemoryAllocation);
            }
            unsafe {
                zero(state.callback_context, tag_table, hash_size);
                *state.hash_salt = 0;
            }
        }
        if unsafe { reserve_failed(state.callback_context) } != 0 {
            return ERROR(ZstdErrorCode::MemoryAllocation);
        }
        let row_log = state.c_params.searchLog.clamp(4, 6);
        debug_assert!(state.c_params.hashLog >= row_log);
        unsafe {
            *state.row_hash_log = state.c_params.hashLog.wrapping_sub(row_log);
        }
    }

    if state.reset_target == 1 && state.c_params.strategy >= 7 {
        unsafe {
            set_pointer(
                state.callback_context,
                RESET_MATCH_POINTER_LIT_FREQ,
                reserve(
                    state.callback_context,
                    RESET_MATCH_RESERVE_ALIGNED64,
                    state.lit_freq_size,
                ),
            );
            set_pointer(
                state.callback_context,
                RESET_MATCH_POINTER_LIT_LENGTH_FREQ,
                reserve(
                    state.callback_context,
                    RESET_MATCH_RESERVE_ALIGNED64,
                    state.lit_length_freq_size,
                ),
            );
            set_pointer(
                state.callback_context,
                RESET_MATCH_POINTER_MATCH_LENGTH_FREQ,
                reserve(
                    state.callback_context,
                    RESET_MATCH_RESERVE_ALIGNED64,
                    state.match_length_freq_size,
                ),
            );
            set_pointer(
                state.callback_context,
                RESET_MATCH_POINTER_OFF_CODE_FREQ,
                reserve(
                    state.callback_context,
                    RESET_MATCH_RESERVE_ALIGNED64,
                    state.off_code_freq_size,
                ),
            );
            set_pointer(
                state.callback_context,
                RESET_MATCH_POINTER_MATCH_TABLE,
                reserve(
                    state.callback_context,
                    RESET_MATCH_RESERVE_ALIGNED64,
                    state.match_size,
                ),
            );
            set_pointer(
                state.callback_context,
                RESET_MATCH_POINTER_PRICE_TABLE,
                reserve(
                    state.callback_context,
                    RESET_MATCH_RESERVE_ALIGNED64,
                    state.optimal_size,
                ),
            );
        }
    }

    unsafe {
        *state.c_params_out = state.c_params;
    }
    if unsafe { reserve_failed(state.callback_context) } != 0 {
        return ERROR(ZstdErrorCode::MemoryAllocation);
    }
    0
}

#[inline]
fn sizeof_local_dict(dict_buffer_present: c_int, dict_size: usize, cdict_size: usize) -> usize {
    let buffer_size = if dict_buffer_present != 0 {
        dict_size
    } else {
        0
    };
    buffer_size.wrapping_add(cdict_size)
}

/// Add the C-owned local-dictionary sizes with C `size_t` wrapping semantics.
#[no_mangle]
pub extern "C" fn ZSTD_rust_sizeofLocalDict(
    dict_buffer_present: c_int,
    dict_size: usize,
    cdict_size: usize,
) -> usize {
    sizeof_local_dict(dict_buffer_present, dict_size, cdict_size)
}

#[inline]
fn sizeof_cdict(object_size: usize, workspace_size: usize) -> usize {
    object_size.wrapping_add(workspace_size)
}

/// Aggregate C-owned dictionary size components with C `size_t` wrapping
/// semantics.
#[no_mangle]
pub extern "C" fn ZSTD_rust_sizeofCDict(objectSize: usize, workspaceSize: usize) -> usize {
    sizeof_cdict(objectSize, workspaceSize)
}

#[inline]
fn sizeof_cctx(
    object_size: usize,
    workspace_size: usize,
    local_dict_size: usize,
    mtctx_size: usize,
) -> usize {
    object_size
        .wrapping_add(workspace_size)
        .wrapping_add(local_dict_size)
        .wrapping_add(mtctx_size)
}

/// Aggregate C-owned context size components with C `size_t` wrapping
/// semantics.
#[no_mangle]
pub extern "C" fn ZSTD_rust_sizeofCCtx(
    object_size: usize,
    workspace_size: usize,
    local_dict_size: usize,
    mtctx_size: usize,
) -> usize {
    sizeof_cctx(object_size, workspace_size, local_dict_size, mtctx_size)
}

#[inline]
fn estimate_workspace_size(
    cctx_space: usize,
    tmp_work_space: usize,
    block_state_space: usize,
    ldm_space: usize,
    ldm_seq_space: usize,
    match_state_size: usize,
    token_space: usize,
    buffer_space: usize,
    external_seq_space: usize,
) -> usize {
    cctx_space
        .wrapping_add(tmp_work_space)
        .wrapping_add(block_state_space)
        .wrapping_add(ldm_space)
        .wrapping_add(ldm_seq_space)
        .wrapping_add(match_state_size)
        .wrapping_add(token_space)
        .wrapping_add(buffer_space)
        .wrapping_add(external_seq_space)
}

/// Aggregate workspace-size components with C `size_t` wrapping semantics.
#[no_mangle]
pub extern "C" fn ZSTD_rust_estimateWorkspaceSize(
    cctx_space: usize,
    tmp_work_space: usize,
    block_state_space: usize,
    ldm_space: usize,
    ldm_seq_space: usize,
    match_state_size: usize,
    token_space: usize,
    buffer_space: usize,
    external_seq_space: usize,
) -> usize {
    estimate_workspace_size(
        cctx_space,
        tmp_work_space,
        block_state_space,
        ldm_space,
        ldm_seq_space,
        match_state_size,
        token_space,
        buffer_space,
        external_seq_space,
    )
}

/// Private C layout sizes needed by the CCtx workspace estimator.
///
/// The scalar sizes keep `ZSTD_CCtx`, `ldmEntry_t`, and the other private C
/// objects opaque while allowing Rust to own the workspace-sizing formula.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default)]
pub struct ZSTD_rustCCtxWorkspaceSizing {
    pub cctxSize: usize,
    pub compressedBlockStateSize: usize,
    pub seqDefSize: usize,
    pub rawSeqSize: usize,
    pub externalSequenceSize: usize,
    pub tmpWorkspaceSize: usize,
    pub wildcopyOverlength: usize,
    pub matchTSize: usize,
    pub optimalTSize: usize,
    pub asanRedzoneSize: usize,
}

const _: () = {
    assert!(size_of::<ZSTD_rustCCtxWorkspaceSizing>() == size_of::<[usize; 10]>());
};

const ZSTD_HASHLOG3_MAX: u32 = 17;

#[inline]
fn cctx_cwksp_alloc_size(size: usize, asan_redzone_size: usize) -> usize {
    if size == 0 {
        0
    } else {
        size.wrapping_add(asan_redzone_size.wrapping_mul(2))
    }
}

#[inline]
fn cctx_cwksp_align(size: usize, alignment: usize) -> usize {
    size.wrapping_add(alignment - 1) & !(alignment - 1)
}

#[inline]
fn cctx_cwksp_aligned64_alloc_size(size: usize, asan_redzone_size: usize) -> usize {
    cctx_cwksp_alloc_size(cctx_cwksp_align(size, 64), asan_redzone_size)
}

#[inline]
fn cctx_ldm_table_size(
    ldm_enable: c_int,
    hash_log: u32,
    bucket_size_log: u32,
    asan_redzone_size: usize,
) -> usize {
    if ldm_enable != ZSTD_RUST_PS_ENABLE {
        return 0;
    }
    let hash_size = 1usize << hash_log;
    let bucket_log = bucket_size_log.min(hash_log);
    let bucket_size = 1usize << (hash_log - bucket_log);
    cctx_cwksp_alloc_size(bucket_size, asan_redzone_size).wrapping_add(cctx_cwksp_alloc_size(
        hash_size.wrapping_mul(2 * size_of::<u32>()),
        asan_redzone_size,
    ))
}

/// Estimate the CCtx workspace using the private C layout sizes supplied by
/// the adapter. This owns the orchestration formerly kept in
/// `ZSTD_estimateCCtxSize_usingCCtxParams_internal()`.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_estimateCCtxWorkspaceSize(
    cparams: ZSTD_compressionParameters,
    ldm_enable: c_int,
    ldm_hash_log: u32,
    ldm_bucket_size_log: u32,
    ldm_min_match_length: u32,
    is_static: c_int,
    use_row_match_finder: c_int,
    buff_in_size: usize,
    buff_out_size: usize,
    pledged_src_size: u64,
    use_sequence_producer: c_int,
    max_block_size: usize,
    sizing: *const ZSTD_rustCCtxWorkspaceSizing,
) -> usize {
    if sizing.is_null() {
        return 0;
    }
    let sizing = unsafe { *sizing };
    let window_limit = 1u64.checked_shl(cparams.windowLog).unwrap_or(u64::MAX);
    let window_size = (window_limit.min(pledged_src_size).min(usize::MAX as u64) as usize).max(1);
    let block_size = ZSTD_resolveMaxBlockSize(max_block_size).min(window_size);
    let max_nb_seq = ZSTD_rust_params_maxNbSeq(block_size, cparams.minMatch, use_sequence_producer);
    let token_space = cctx_cwksp_alloc_size(
        sizing.wildcopyOverlength.wrapping_add(block_size),
        sizing.asanRedzoneSize,
    )
    .wrapping_add(cctx_cwksp_aligned64_alloc_size(
        max_nb_seq.wrapping_mul(sizing.seqDefSize),
        sizing.asanRedzoneSize,
    ))
    .wrapping_add(3usize.wrapping_mul(cctx_cwksp_alloc_size(
        max_nb_seq.wrapping_mul(size_of::<u8>()),
        sizing.asanRedzoneSize,
    )));
    let tmp_workspace = cctx_cwksp_alloc_size(sizing.tmpWorkspaceSize, sizing.asanRedzoneSize);
    let block_state_space = 2usize.wrapping_mul(cctx_cwksp_alloc_size(
        sizing.compressedBlockStateSize,
        sizing.asanRedzoneSize,
    ));
    let match_state_sizing = ZSTD_rustMatchStateSizing {
        hashLog3Max: ZSTD_HASHLOG3_MAX,
        matchTSize: sizing.matchTSize,
        optimalTSize: sizing.optimalTSize,
        asanRedzoneSize: sizing.asanRedzoneSize,
    };
    let match_state_size = unsafe {
        ZSTD_rust_params_estimateMatchStateSize(
            cparams,
            use_row_match_finder,
            0,
            1,
            &match_state_sizing,
        )
    };
    let ldm_space = cctx_ldm_table_size(
        ldm_enable,
        ldm_hash_log,
        ldm_bucket_size_log,
        sizing.asanRedzoneSize,
    );
    let max_nb_ldm_seq = if ldm_enable == ZSTD_RUST_PS_ENABLE && ldm_min_match_length != 0 {
        block_size / ldm_min_match_length as usize
    } else {
        0
    };
    let ldm_seq_space = if ldm_enable == ZSTD_RUST_PS_ENABLE {
        cctx_cwksp_aligned64_alloc_size(
            max_nb_ldm_seq.wrapping_mul(sizing.rawSeqSize),
            sizing.asanRedzoneSize,
        )
    } else {
        0
    };
    let buffer_space = cctx_cwksp_alloc_size(buff_in_size, sizing.asanRedzoneSize)
        .wrapping_add(cctx_cwksp_alloc_size(buff_out_size, sizing.asanRedzoneSize));
    let cctx_space = if is_static != 0 {
        cctx_cwksp_alloc_size(sizing.cctxSize, sizing.asanRedzoneSize)
    } else {
        0
    };
    let external_seq_space = if use_sequence_producer != 0 {
        cctx_cwksp_aligned64_alloc_size(
            crate::zstd_compress_api::ZSTD_sequenceBound(block_size)
                .wrapping_mul(sizing.externalSequenceSize),
            sizing.asanRedzoneSize,
        )
    } else {
        0
    };

    estimate_workspace_size(
        cctx_space,
        tmp_workspace,
        block_state_space,
        ldm_space,
        ldm_seq_space,
        match_state_size,
        token_space,
        buffer_space,
        external_seq_space,
    )
}

/// Scalar outputs computed while resetting a private C compression context.
///
/// C still owns workspace resizing and all private reservations. Rust owns
/// this policy projection so the reset formula is testable without exposing
/// `ZSTD_CCtx` or `ZSTD_cwksp` layouts across the ABI.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_rustCCtxResetPlan {
    pub windowSize: usize,
    pub blockSize: usize,
    pub maxNbSeq: usize,
    pub buffInSize: usize,
    pub buffOutSize: usize,
    pub maxNbLdmSeq: usize,
    pub maxNbExternalSeq: usize,
    pub neededSpace: usize,
    pub needsIndexReset: c_int,
}

/// Scalar inputs needed to plan a private C compression-context reset.
///
/// The C adapter supplies resolved parameters, private object sizes, and the
/// already-reduced index/dictionary predicates. No private C pointer or
/// layout is passed through this record.
#[repr(C)]
#[derive(Clone, Copy, Debug)]
pub struct ZSTD_rustCCtxResetState {
    pub cParams: ZSTD_compressionParameters,
    pub ldmEnable: c_int,
    pub ldmHashLog: c_uint,
    pub ldmBucketSizeLog: c_uint,
    pub ldmMinMatchLength: c_uint,
    pub isStatic: c_int,
    pub useRowMatchFinder: c_int,
    pub inBufferBuffered: c_int,
    pub outBufferBuffered: c_int,
    pub useSequenceProducer: c_int,
    pub initialized: c_int,
    pub indexTooClose: c_int,
    pub dictTooBig: c_int,
    pub pledgedSrcSize: u64,
    pub maxBlockSize: usize,
    pub sizing: *const ZSTD_rustCCtxWorkspaceSizing,
    pub plan: *mut ZSTD_rustCCtxResetPlan,
}

const _: () = {
    assert!(size_of::<ZSTD_rustCCtxResetPlan>() == 9 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, windowSize) == 0);
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, blockSize) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, maxNbSeq) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, buffInSize) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, buffOutSize) == 4 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, maxNbLdmSeq) == 5 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, maxNbExternalSeq) == 6 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, neededSpace) == 7 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rustCCtxResetPlan, needsIndexReset) == size_of::<[usize; 8]>());
    assert!(offset_of!(ZSTD_rustCCtxResetState, cParams) == 0);
    assert!(
        offset_of!(ZSTD_rustCCtxResetState, ldmEnable) == size_of::<ZSTD_compressionParameters>()
    );
    assert!(
        offset_of!(ZSTD_rustCCtxResetState, pledgedSrcSize)
            > offset_of!(ZSTD_rustCCtxResetState, dictTooBig)
    );
    assert!(
        offset_of!(ZSTD_rustCCtxResetState, maxBlockSize)
            == offset_of!(ZSTD_rustCCtxResetState, pledgedSrcSize) + size_of::<u64>()
    );
    assert!(
        offset_of!(ZSTD_rustCCtxResetState, sizing)
            == offset_of!(ZSTD_rustCCtxResetState, maxBlockSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rustCCtxResetState, plan)
            == offset_of!(ZSTD_rustCCtxResetState, sizing) + size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rustCCtxResetState>()
            == offset_of!(ZSTD_rustCCtxResetState, plan) + size_of::<usize>()
    );
};

/// Compute the scalar portion of `ZSTD_resetCCtx_internal()`.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_planCCtxReset(state: *const ZSTD_rustCCtxResetState) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.sizing.is_null() || state.plan.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let ldm_enabled = state.ldmEnable == ZSTD_RUST_PS_ENABLE;
    if ldm_enabled && state.ldmMinMatchLength == 0 {
        return ERROR(ZstdErrorCode::Generic);
    }

    let window_limit = 1u64
        .checked_shl(state.cParams.windowLog)
        .unwrap_or(u64::MAX);
    let window_size = (window_limit
        .min(state.pledgedSrcSize)
        .min(usize::MAX as u64) as usize)
        .max(1);
    let block_size = state.maxBlockSize.min(window_size);
    let max_nb_seq = ZSTD_rust_params_maxNbSeq(
        block_size,
        state.cParams.minMatch,
        state.useSequenceProducer,
    );
    let buff_out_size = if state.outBufferBuffered != 0 {
        crate::zstd_compress_api::ZSTD_compressBound(block_size).wrapping_add(1)
    } else {
        0
    };
    let buff_in_size = if state.inBufferBuffered != 0 {
        window_size.wrapping_add(block_size)
    } else {
        0
    };
    let max_nb_ldm_seq = if ldm_enabled {
        block_size / state.ldmMinMatchLength as usize
    } else {
        0
    };
    let max_nb_external_seq = if state.useSequenceProducer != 0 {
        crate::zstd_compress_api::ZSTD_sequenceBound(block_size)
    } else {
        0
    };
    let needed_space = unsafe {
        ZSTD_rust_estimateCCtxWorkspaceSize(
            state.cParams,
            state.ldmEnable,
            state.ldmHashLog,
            state.ldmBucketSizeLog,
            state.ldmMinMatchLength,
            state.isStatic,
            state.useRowMatchFinder,
            buff_in_size,
            buff_out_size,
            state.pledgedSrcSize,
            state.useSequenceProducer,
            state.maxBlockSize,
            state.sizing,
        )
    };
    if ERR_isError(needed_space) {
        return needed_space;
    }

    unsafe {
        *state.plan = ZSTD_rustCCtxResetPlan {
            windowSize: window_size,
            blockSize: block_size,
            maxNbSeq: max_nb_seq,
            buffInSize: buff_in_size,
            buffOutSize: buff_out_size,
            maxNbLdmSeq: max_nb_ldm_seq,
            maxNbExternalSeq: max_nb_external_seq,
            neededSpace: needed_space,
            needsIndexReset: c_int::from(
                state.indexTooClose != 0 || state.dictTooBig != 0 || state.initialized == 0,
            ),
        };
    }
    0
}

type ResetCCtxStorageSetPointer = unsafe extern "C" fn(*mut c_void, c_int, *mut c_void);
type ResetCCtxStorageSetSize = unsafe extern "C" fn(*mut c_void, c_int, usize);
type ResetCCtxStorageSetInt = unsafe extern "C" fn(*mut c_void, c_int, c_int);
type ResetCCtxStorageReserve = unsafe extern "C" fn(*mut c_void, c_int, usize) -> *mut c_void;
type ResetCCtxStorageReserveFailed = unsafe extern "C" fn(*mut c_void) -> c_int;
type ResetCCtxStorageZero = unsafe extern "C" fn(*mut c_void, *mut c_void, usize);
type ResetCCtxStorageCallback = unsafe extern "C" fn(*mut c_void);

const RESET_CCTX_RESERVE_ALIGNED64: c_int = 0;
const RESET_CCTX_RESERVE_BUFFER: c_int = 1;

const RESET_CCTX_POINTER_SEQ_START: c_int = 0;
const RESET_CCTX_POINTER_LDM_HASH: c_int = 1;
const RESET_CCTX_POINTER_LDM_SEQUENCES: c_int = 2;
const RESET_CCTX_POINTER_EXTERNAL_SEQUENCES: c_int = 3;
const RESET_CCTX_POINTER_LITERALS: c_int = 4;
const RESET_CCTX_POINTER_INPUT_BUFFER: c_int = 5;
const RESET_CCTX_POINTER_OUTPUT_BUFFER: c_int = 6;
const RESET_CCTX_POINTER_LL_CODE: c_int = 7;
const RESET_CCTX_POINTER_ML_CODE: c_int = 8;
const RESET_CCTX_POINTER_OF_CODE: c_int = 9;
const RESET_CCTX_POINTER_LDM_BUCKETS: c_int = 10;
const RESET_CCTX_POINTER_PREV_CBLOCK: c_int = 11;
const RESET_CCTX_POINTER_NEXT_CBLOCK: c_int = 12;
const RESET_CCTX_POINTER_TMP_WORKSPACE: c_int = 13;

const RESET_CCTX_SIZE_MAX_NB_SEQ: c_int = 0;
const RESET_CCTX_SIZE_MAX_NB_LIT: c_int = 1;
const RESET_CCTX_SIZE_MAX_NB_LDM_SEQ: c_int = 2;
const RESET_CCTX_SIZE_EXTERNAL_SEQ_CAPACITY: c_int = 3;
const RESET_CCTX_SIZE_INPUT_BUFFER: c_int = 4;
const RESET_CCTX_SIZE_OUTPUT_BUFFER: c_int = 5;
const RESET_CCTX_SIZE_TMP_WORKSPACE: c_int = 6;

const RESET_CCTX_INT_BUFFERED_POLICY: c_int = 0;
const RESET_CCTX_INT_INITIALIZED: c_int = 1;
const RESET_CCTX_INDEX_RESET: c_int = 1;

/// C-owned workspace/layout projection for the post-match-state reset tail.
///
/// Rust owns the reservation order and size policy. C retains the private
/// `ZSTD_CCtx`/`ldmState_t` layouts and implements the workspace callbacks.
#[repr(C)]
pub struct ZSTD_rust_resetCCtxStorageState {
    pub callbackContext: *mut c_void,
    pub ldmEnable: c_int,
    pub hasExtSeqProd: c_int,
    pub hashLog: c_uint,
    pub bucketSizeLog: c_uint,
    pub blockSize: usize,
    pub maxNbSeq: usize,
    pub maxNbLdmSeq: usize,
    pub maxNbExternalSeq: usize,
    pub buffInSize: usize,
    pub buffOutSize: usize,
    pub seqDefSize: usize,
    pub ldmEntrySize: usize,
    pub rawSeqSize: usize,
    pub externalSequenceSize: usize,
    pub byteSize: usize,
    pub wildcopyOverlength: usize,
    pub bufferedPolicy: c_int,
    pub setPointer: Option<ResetCCtxStorageSetPointer>,
    pub setSize: Option<ResetCCtxStorageSetSize>,
    pub setInt: Option<ResetCCtxStorageSetInt>,
    pub reserve: Option<ResetCCtxStorageReserve>,
    pub reserveFailed: Option<ResetCCtxStorageReserveFailed>,
    pub zero: Option<ResetCCtxStorageZero>,
    pub windowInit: Option<ResetCCtxStorageCallback>,
    pub resetExternalSequences: Option<ResetCCtxStorageCallback>,
}

const _: () = {
    assert!(size_of::<ResetCCtxStorageSetPointer>() == size_of::<usize>());
    assert!(size_of::<ResetCCtxStorageSetSize>() == size_of::<usize>());
    assert!(size_of::<ResetCCtxStorageSetInt>() == size_of::<usize>());
    assert!(size_of::<ResetCCtxStorageReserve>() == size_of::<usize>());
    assert!(size_of::<ResetCCtxStorageReserveFailed>() == size_of::<usize>());
    assert!(size_of::<ResetCCtxStorageZero>() == size_of::<usize>());
    assert!(size_of::<ResetCCtxStorageCallback>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetCCtxStorageState, callbackContext) == 0);
    assert!(offset_of!(ZSTD_rust_resetCCtxStorageState, ldmEnable) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, hasExtSeqProd)
            == size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, hashLog)
            > offset_of!(ZSTD_rust_resetCCtxStorageState, hasExtSeqProd)
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, bucketSizeLog)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, hashLog) + size_of::<c_uint>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, blockSize)
            > offset_of!(ZSTD_rust_resetCCtxStorageState, bucketSizeLog)
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, maxNbSeq)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, blockSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, maxNbLdmSeq)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, maxNbSeq) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, maxNbExternalSeq)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, maxNbLdmSeq) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, buffInSize)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, maxNbExternalSeq) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, buffOutSize)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, buffInSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, seqDefSize)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, buffOutSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, ldmEntrySize)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, seqDefSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, rawSeqSize)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, ldmEntrySize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, externalSequenceSize)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, rawSeqSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, byteSize)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, externalSequenceSize)
                + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, wildcopyOverlength)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, byteSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, bufferedPolicy)
            > offset_of!(ZSTD_rust_resetCCtxStorageState, wildcopyOverlength)
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, setSize)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, setPointer) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, setInt)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, setSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxStorageState, reserve)
            == offset_of!(ZSTD_rust_resetCCtxStorageState, setInt) + size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_resetCCtxStorageState>()
            == offset_of!(ZSTD_rust_resetCCtxStorageState, resetExternalSequences)
                + size_of::<usize>()
    );
};

type ResetCCtxWorkspaceCreate = unsafe extern "C" fn(*mut c_void, usize) -> usize;
type ResetCCtxWorkspaceReserveObject = unsafe extern "C" fn(*mut c_void, usize) -> *mut c_void;
type ResetCCtxTailCallback = unsafe extern "C" fn(*mut c_void) -> usize;

/// C-owned workspace operations used by the CCtx reset policy.
///
/// Rust owns the resize decision, error ordering, object-reservation order,
/// and workspace-clear boundary. C retains the workspace representation,
/// allocator, and private CCtx publication callbacks.
#[repr(C)]
pub struct ZSTD_rust_resetCCtxWorkspaceState {
    callbackContext: *mut c_void,
    isStatic: c_int,
    workspaceTooSmall: c_int,
    workspaceWasteful: c_int,
    neededSpace: usize,
    compressedBlockStateSize: usize,
    tmpWorkspaceSize: usize,
    needsIndexReset: *mut c_int,
    bumpOversizedDuration: Option<ResetCCtxStorageCallback>,
    freeWorkspace: Option<ResetCCtxStorageCallback>,
    createWorkspace: Option<ResetCCtxWorkspaceCreate>,
    reserveObject: Option<ResetCCtxWorkspaceReserveObject>,
    setPointer: Option<ResetCCtxStorageSetPointer>,
    setSize: Option<ResetCCtxStorageSetSize>,
    clearWorkspace: Option<ResetCCtxStorageCallback>,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_resetCCtxWorkspaceState, callbackContext) == 0);
    assert!(offset_of!(ZSTD_rust_resetCCtxWorkspaceState, isStatic) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, workspaceTooSmall)
            == size_of::<usize>() + size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, workspaceWasteful)
            == size_of::<usize>() + 2 * size_of::<c_int>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, neededSpace)
            > offset_of!(ZSTD_rust_resetCCtxWorkspaceState, workspaceWasteful)
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, compressedBlockStateSize)
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, neededSpace) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, tmpWorkspaceSize)
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, compressedBlockStateSize)
                + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, needsIndexReset)
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, tmpWorkspaceSize) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, freeWorkspace)
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, bumpOversizedDuration)
                + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, createWorkspace)
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, freeWorkspace) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, reserveObject)
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, createWorkspace) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, setPointer)
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, reserveObject) + size_of::<usize>()
    );
    assert!(
        offset_of!(ZSTD_rust_resetCCtxWorkspaceState, setSize)
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, setPointer) + size_of::<usize>()
    );
    assert!(
        size_of::<ZSTD_rust_resetCCtxWorkspaceState>()
            == offset_of!(ZSTD_rust_resetCCtxWorkspaceState, clearWorkspace) + size_of::<usize>()
    );
};

/// C-owned operations used by the post-workspace CCtx reset tail.
///
/// Rust owns the operation order, compressed-block reset, and error
/// propagation. C retains the private context initialization, match-state
/// reset, and storage publication operations.
#[repr(C)]
pub struct ZSTD_rust_resetCCtxTailState {
    callbackContext: *mut c_void,
    initialize: Option<ResetCCtxStorageCallback>,
    compressedBlockState: *mut ZSTD_compressedBlockState_t,
    resetMatchState: Option<ResetCCtxTailCallback>,
    resetStorage: Option<ResetCCtxTailCallback>,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_resetCCtxTailState, callbackContext) == 0);
    assert!(offset_of!(ZSTD_rust_resetCCtxTailState, initialize) == size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_resetCCtxTailState, compressedBlockState) == 2 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_resetCCtxTailState, resetMatchState) == 3 * size_of::<usize>());
    assert!(
        size_of::<ZSTD_rust_resetCCtxTailState>()
            == offset_of!(ZSTD_rust_resetCCtxTailState, resetStorage) + size_of::<usize>()
    );
};

type ResetCCtxWorkspacePrepare =
    unsafe extern "C" fn(*mut c_void, usize, usize, usize, *mut c_int, *mut c_int);
type ResetCCtxTailPrepare = unsafe extern "C" fn(*mut c_void, usize, c_int);

/// State for composing the already-projected CCtx reset policies.
///
/// Rust owns the plan/workspace/tail order and the scalar hand-off between
/// those helpers. C retains the workspace checks, context initialization,
/// match-state reset, and private pointer publication behind callbacks.
#[repr(C)]
pub struct ZSTD_rust_resetCCtxInternalState {
    pub callbackContext: *mut c_void,
    pub resetState: *const ZSTD_rustCCtxResetState,
    pub storageState: *mut ZSTD_rust_resetCCtxStorageState,
    pub workspaceState: *mut ZSTD_rust_resetCCtxWorkspaceState,
    pub tailState: *mut ZSTD_rust_resetCCtxTailState,
    pub prepareWorkspace: Option<ResetCCtxWorkspacePrepare>,
    pub prepareTail: Option<ResetCCtxTailPrepare>,
}

const _: () = {
    assert!(size_of::<ResetCCtxWorkspacePrepare>() == size_of::<usize>());
    assert!(size_of::<ResetCCtxTailPrepare>() == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetCCtxInternalState, callbackContext) == 0);
    assert!(offset_of!(ZSTD_rust_resetCCtxInternalState, resetState) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetCCtxInternalState, storageState) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetCCtxInternalState, workspaceState) == 3 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_resetCCtxInternalState, tailState) == 4 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_resetCCtxInternalState, prepareWorkspace) == 5 * size_of::<usize>()
    );
    assert!(offset_of!(ZSTD_rust_resetCCtxInternalState, prepareTail) == 6 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_resetCCtxInternalState>() == 7 * size_of::<usize>());
};

#[inline]
fn project_cctx_reset_plan(
    plan: &ZSTD_rustCCtxResetPlan,
    storage_state: &mut ZSTD_rust_resetCCtxStorageState,
    workspace_state: &mut ZSTD_rust_resetCCtxWorkspaceState,
) {
    storage_state.blockSize = plan.blockSize;
    storage_state.maxNbSeq = plan.maxNbSeq;
    storage_state.maxNbLdmSeq = plan.maxNbLdmSeq;
    storage_state.maxNbExternalSeq = plan.maxNbExternalSeq;
    storage_state.buffInSize = plan.buffInSize;
    storage_state.buffOutSize = plan.buffOutSize;
    workspace_state.neededSpace = plan.neededSpace;
}

#[inline]
fn run_cctx_reset_policy(
    plan: impl FnOnce() -> usize,
    prepare_workspace: impl FnOnce(),
    reset_workspace: impl FnOnce() -> usize,
    prepare_tail: impl FnOnce(),
    reset_tail: impl FnOnce() -> usize,
) -> usize {
    let result = plan();
    if ERR_isError(result) {
        return result;
    }
    prepare_workspace();
    let result = reset_workspace();
    if ERR_isError(result) {
        return result;
    }
    prepare_tail();
    reset_tail()
}

/// Compose the private CCtx reset without moving C-only layout operations.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_resetCCtxInternal(
    state: *const ZSTD_rust_resetCCtxInternalState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    let Some(prepare_workspace) = state.prepareWorkspace else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(prepare_tail) = state.prepareTail else {
        return ERROR(ZstdErrorCode::Generic);
    };
    if state.callbackContext.is_null()
        || state.resetState.is_null()
        || state.storageState.is_null()
        || state.workspaceState.is_null()
        || state.tailState.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }

    let reset_state = unsafe { &*state.resetState };
    if reset_state.plan.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let workspace_state = unsafe { &*state.workspaceState };
    if workspace_state.needsIndexReset.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let plan = reset_state.plan;
    let reset_state_ptr = state.resetState;
    let storage_state_ptr = state.storageState;
    let workspace_state_ptr = state.workspaceState;
    let tail_state_ptr = state.tailState;
    let callback_context = state.callbackContext;

    run_cctx_reset_policy(
        || unsafe {
            let result = ZSTD_rust_planCCtxReset(reset_state_ptr);
            if ERR_isError(result) {
                return result;
            }
            let plan = &*plan;
            let storage_state = &mut *storage_state_ptr;
            let workspace_state = &mut *workspace_state_ptr;
            project_cctx_reset_plan(plan, storage_state, workspace_state);
            *workspace_state.needsIndexReset = plan.needsIndexReset;
            0
        },
        || unsafe {
            let plan = &*plan;
            let workspace_state = &mut *workspace_state_ptr;
            prepare_workspace(
                callback_context,
                plan.neededSpace,
                plan.windowSize,
                plan.blockSize,
                &mut workspace_state.workspaceTooSmall,
                &mut workspace_state.workspaceWasteful,
            );
        },
        || unsafe { ZSTD_rust_resetCCtxWorkspace(workspace_state_ptr) },
        || unsafe {
            let workspace_state = &*workspace_state_ptr;
            prepare_tail(
                callback_context,
                (&*plan).blockSize,
                *workspace_state.needsIndexReset,
            );
        },
        || unsafe { ZSTD_rust_resetCCtxTail(tail_state_ptr) },
    )
}

/// Reserve and publish the private CCtx storage that follows match-state reset.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_resetCCtxStorage(
    state: *const ZSTD_rust_resetCCtxStorageState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.callbackContext.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let Some(set_pointer) = state.setPointer else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(set_size) = state.setSize else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(set_int) = state.setInt else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(reserve_callback) = state.reserve else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(reserve_failed) = state.reserveFailed else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(zero) = state.zero else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(window_init) = state.windowInit else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(reset_external_sequences) = state.resetExternalSequences else {
        return ERROR(ZstdErrorCode::Generic);
    };

    let reserve = |kind: c_int, size: usize| -> Result<*mut c_void, usize> {
        let pointer = unsafe { reserve_callback(state.callbackContext, kind, size) };
        if unsafe { reserve_failed(state.callbackContext) } != 0 {
            Err(ERROR(ZstdErrorCode::MemoryAllocation))
        } else {
            Ok(pointer)
        }
    };
    let publish_pointer = |kind: c_int, pointer: *mut c_void| unsafe {
        set_pointer(state.callbackContext, kind, pointer)
    };
    let publish_size =
        |kind: c_int, value: usize| unsafe { set_size(state.callbackContext, kind, value) };

    let sequence_start = match reserve(
        RESET_CCTX_RESERVE_ALIGNED64,
        state.maxNbSeq.wrapping_mul(state.seqDefSize),
    ) {
        Ok(pointer) => pointer,
        Err(error) => return error,
    };
    publish_pointer(RESET_CCTX_POINTER_SEQ_START, sequence_start);

    if state.ldmEnable == ZSTD_RUST_PS_ENABLE {
        if state.bucketSizeLog > state.hashLog {
            return ERROR(ZstdErrorCode::Generic);
        }
        let Some(hash_size) = 1usize.checked_shl(state.hashLog) else {
            return ERROR(ZstdErrorCode::Generic);
        };
        let hash_table = match reserve(
            RESET_CCTX_RESERVE_ALIGNED64,
            hash_size.wrapping_mul(state.ldmEntrySize),
        ) {
            Ok(pointer) => pointer,
            Err(error) => return error,
        };
        publish_pointer(RESET_CCTX_POINTER_LDM_HASH, hash_table);
        unsafe {
            zero(
                state.callbackContext,
                hash_table,
                hash_size.wrapping_mul(state.ldmEntrySize),
            )
        };

        let ldm_sequences = match reserve(
            RESET_CCTX_RESERVE_ALIGNED64,
            state.maxNbLdmSeq.wrapping_mul(state.rawSeqSize),
        ) {
            Ok(pointer) => pointer,
            Err(error) => return error,
        };
        publish_pointer(RESET_CCTX_POINTER_LDM_SEQUENCES, ldm_sequences);
        publish_size(RESET_CCTX_SIZE_MAX_NB_LDM_SEQ, state.maxNbLdmSeq);
        unsafe { window_init(state.callbackContext) };
    }

    if state.hasExtSeqProd != 0 {
        let external_sequences = match reserve(
            RESET_CCTX_RESERVE_ALIGNED64,
            state
                .maxNbExternalSeq
                .wrapping_mul(state.externalSequenceSize),
        ) {
            Ok(pointer) => pointer,
            Err(error) => return error,
        };
        publish_pointer(RESET_CCTX_POINTER_EXTERNAL_SEQUENCES, external_sequences);
        publish_size(
            RESET_CCTX_SIZE_EXTERNAL_SEQ_CAPACITY,
            state.maxNbExternalSeq,
        );
    }

    let literals = match reserve(
        RESET_CCTX_RESERVE_BUFFER,
        state.blockSize.wrapping_add(state.wildcopyOverlength),
    ) {
        Ok(pointer) => pointer,
        Err(error) => return error,
    };
    publish_pointer(RESET_CCTX_POINTER_LITERALS, literals);
    publish_size(RESET_CCTX_SIZE_MAX_NB_LIT, state.blockSize);
    unsafe {
        set_int(
            state.callbackContext,
            RESET_CCTX_INT_BUFFERED_POLICY,
            state.bufferedPolicy,
        )
    };

    let input_buffer = match reserve(RESET_CCTX_RESERVE_BUFFER, state.buffInSize) {
        Ok(pointer) => pointer,
        Err(error) => return error,
    };
    publish_pointer(RESET_CCTX_POINTER_INPUT_BUFFER, input_buffer);
    publish_size(RESET_CCTX_SIZE_INPUT_BUFFER, state.buffInSize);

    let output_buffer = match reserve(RESET_CCTX_RESERVE_BUFFER, state.buffOutSize) {
        Ok(pointer) => pointer,
        Err(error) => return error,
    };
    publish_pointer(RESET_CCTX_POINTER_OUTPUT_BUFFER, output_buffer);
    publish_size(RESET_CCTX_SIZE_OUTPUT_BUFFER, state.buffOutSize);

    if state.ldmEnable == ZSTD_RUST_PS_ENABLE {
        let bucket_count = match 1usize.checked_shl(state.hashLog - state.bucketSizeLog) {
            Some(count) => count,
            None => return ERROR(ZstdErrorCode::Generic),
        };
        let bucket_offsets = match reserve(
            RESET_CCTX_RESERVE_BUFFER,
            bucket_count.wrapping_mul(state.byteSize),
        ) {
            Ok(pointer) => pointer,
            Err(error) => return error,
        };
        publish_pointer(RESET_CCTX_POINTER_LDM_BUCKETS, bucket_offsets);
        unsafe {
            zero(
                state.callbackContext,
                bucket_offsets,
                bucket_count.wrapping_mul(state.byteSize),
            )
        };
    }

    unsafe { reset_external_sequences(state.callbackContext) };
    publish_size(RESET_CCTX_SIZE_MAX_NB_SEQ, state.maxNbSeq);

    let ll_code = match reserve(
        RESET_CCTX_RESERVE_BUFFER,
        state.maxNbSeq.wrapping_mul(state.byteSize),
    ) {
        Ok(pointer) => pointer,
        Err(error) => return error,
    };
    publish_pointer(RESET_CCTX_POINTER_LL_CODE, ll_code);
    let ml_code = match reserve(
        RESET_CCTX_RESERVE_BUFFER,
        state.maxNbSeq.wrapping_mul(state.byteSize),
    ) {
        Ok(pointer) => pointer,
        Err(error) => return error,
    };
    publish_pointer(RESET_CCTX_POINTER_ML_CODE, ml_code);
    let of_code = match reserve(
        RESET_CCTX_RESERVE_BUFFER,
        state.maxNbSeq.wrapping_mul(state.byteSize),
    ) {
        Ok(pointer) => pointer,
        Err(error) => return error,
    };
    publish_pointer(RESET_CCTX_POINTER_OF_CODE, of_code);
    unsafe { set_int(state.callbackContext, RESET_CCTX_INT_INITIALIZED, 1) };
    0
}

/// Own the CCtx workspace resize, object reservation, and clear order.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_resetCCtxWorkspace(
    state: *const ZSTD_rust_resetCCtxWorkspaceState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.callbackContext.is_null() || state.needsIndexReset.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let Some(bump_oversized_duration) = state.bumpOversizedDuration else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(free_workspace) = state.freeWorkspace else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(create_workspace) = state.createWorkspace else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(reserve_object) = state.reserveObject else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(set_pointer) = state.setPointer else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(set_size) = state.setSize else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(clear_workspace) = state.clearWorkspace else {
        return ERROR(ZstdErrorCode::Generic);
    };

    unsafe {
        if state.isStatic == 0 {
            bump_oversized_duration(state.callbackContext);
        }
        let resize_workspace = state.workspaceTooSmall != 0 || state.workspaceWasteful != 0;
        if resize_workspace {
            if state.isStatic != 0 {
                return ERROR(ZstdErrorCode::MemoryAllocation);
            }
            *state.needsIndexReset = RESET_CCTX_INDEX_RESET;
            free_workspace(state.callbackContext);
            let result = create_workspace(state.callbackContext, state.neededSpace);
            if ERR_isError(result) {
                return result;
            }

            let previous = reserve_object(state.callbackContext, state.compressedBlockStateSize);
            if previous.is_null() {
                return ERROR(ZstdErrorCode::MemoryAllocation);
            }
            set_pointer(
                state.callbackContext,
                RESET_CCTX_POINTER_PREV_CBLOCK,
                previous,
            );

            let next = reserve_object(state.callbackContext, state.compressedBlockStateSize);
            if next.is_null() {
                return ERROR(ZstdErrorCode::MemoryAllocation);
            }
            set_pointer(state.callbackContext, RESET_CCTX_POINTER_NEXT_CBLOCK, next);

            let tmp_workspace = reserve_object(state.callbackContext, state.tmpWorkspaceSize);
            if tmp_workspace.is_null() {
                return ERROR(ZstdErrorCode::MemoryAllocation);
            }
            set_pointer(
                state.callbackContext,
                RESET_CCTX_POINTER_TMP_WORKSPACE,
                tmp_workspace,
            );
            set_size(
                state.callbackContext,
                RESET_CCTX_SIZE_TMP_WORKSPACE,
                state.tmpWorkspaceSize,
            );
        }
        clear_workspace(state.callbackContext);
    }
    0
}

/// Own the callback order for the post-workspace CCtx reset tail.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_resetCCtxTail(
    state: *const ZSTD_rust_resetCCtxTailState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.callbackContext.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let Some(initialize) = state.initialize else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(reset_match_state) = state.resetMatchState else {
        return ERROR(ZstdErrorCode::Generic);
    };
    let Some(reset_storage) = state.resetStorage else {
        return ERROR(ZstdErrorCode::Generic);
    };
    if state.compressedBlockState.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    unsafe {
        initialize(state.callbackContext);
        ZSTD_rust_resetCompressedBlockState(state.compressedBlockState);
        let result = reset_match_state(state.callbackContext);
        if ERR_isError(result) {
            return result;
        }
        let result = reset_storage(state.callbackContext);
        if ERR_isError(result) {
            return result;
        }
    }
    0
}

#[inline]
fn max_estimate_cctx_size(
    estimate0: usize,
    estimate1: usize,
    estimate2: usize,
    estimate3: usize,
) -> usize {
    estimate0.max(estimate1).max(estimate2).max(estimate3)
}

type EstimateCCtxSizeGetCParamsFn =
    unsafe extern "C" fn(*mut c_void, c_int, u64) -> ZSTD_compressionParameters;
type EstimateCCtxSizeEstimateFn =
    unsafe extern "C" fn(*mut c_void, ZSTD_compressionParameters) -> usize;

/// Rust owns the fixed source-size tier policy for CCtx estimates. C keeps
/// the configuration-sensitive parameter lookup and workspace estimator behind
/// callbacks, so this seam does not expose any private context layout.
#[repr(C)]
pub struct ZSTD_rust_estimateCCtxSizeState {
    callback_context: *mut c_void,
    compression_level: c_int,
    get_c_params: EstimateCCtxSizeGetCParamsFn,
    estimate: EstimateCCtxSizeEstimateFn,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_estimateCCtxSizeState, callback_context) == 0);
    assert!(offset_of!(ZSTD_rust_estimateCCtxSizeState, compression_level) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_estimateCCtxSizeState, get_c_params) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_estimateCCtxSizeState, estimate) == 3 * size_of::<usize>());
    assert!(size_of::<ZSTD_rust_estimateCCtxSizeState>() == 4 * size_of::<usize>());
};

/// Evaluate the four source-size tiers used by `ZSTD_estimateCCtxSize()` and
/// return the largest raw result, including size_t-encoded error values.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_estimateCCtxSizeInternal(
    state: *const ZSTD_rust_estimateCCtxSizeState,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let state = unsafe { &*state };
    let source_size_tiers = [16 * 1024, 128 * 1024, 256 * 1024, ZSTD_CONTENTSIZE_UNKNOWN];
    let mut estimates = [0usize; 4];
    for (estimate, &source_size_hint) in estimates.iter_mut().zip(source_size_tiers.iter()) {
        let c_params = unsafe {
            (state.get_c_params)(
                state.callback_context,
                state.compression_level,
                source_size_hint,
            )
        };
        *estimate = unsafe { (state.estimate)(state.callback_context, c_params) };
    }

    max_estimate_cctx_size(estimates[0], estimates[1], estimates[2], estimates[3])
}

/// Return the largest raw estimate, including any C size_t error values.
#[no_mangle]
pub extern "C" fn ZSTD_rust_maxEstimateCCtxSize(
    estimate0: usize,
    estimate1: usize,
    estimate2: usize,
    estimate3: usize,
) -> usize {
    max_estimate_cctx_size(estimate0, estimate1, estimate2, estimate3)
}

#[inline]
fn reduce_table_internal(table: &mut [u32], reducer_value: u32, preserve_mark: bool) {
    debug_assert_eq!(table.len() % ZSTD_ROWSIZE, 0);
    debug_assert!(table.len() < (1usize << 31));

    /* Protect special index values < ZSTD_WINDOW_START_INDEX. */
    let reducer_threshold = reducer_value.wrapping_add(ZSTD_WINDOW_START_INDEX);
    let mut rows = table.chunks_exact_mut(ZSTD_ROWSIZE);
    for row in &mut rows {
        for cell in row {
            let value = *cell;
            *cell = if preserve_mark && value == ZSTD_DUBT_UNSORTED_MARK {
                /* Keep the btlazy2 unsorted marker across table reduction. */
                ZSTD_DUBT_UNSORTED_MARK
            } else if value < reducer_threshold {
                0
            } else {
                value.wrapping_sub(reducer_value)
            };
        }
    }
    debug_assert!(rows.into_remainder().is_empty());
}

/// Rust implementation of the C match-table reduction leaf.
///
/// The C caller supplies a clear zero/one `preserve_mark` value for the
/// strategy-specific btlazy2 policy.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_reduceTable(
    table: *mut u32,
    size: u32,
    reducer_value: u32,
    preserve_mark: c_int,
) {
    debug_assert!(!table.is_null() || size == 0);
    debug_assert_eq!(size % ZSTD_ROWSIZE as u32, 0);
    debug_assert!(size < (1u32 << 31));
    if size == 0 {
        return;
    }

    let table = unsafe { std::slice::from_raw_parts_mut(table, size as usize) };
    reduce_table_internal(table, reducer_value, preserve_mark != 0);
}

/// Reduce the match tables selected by C's stateful overflow-correction path.
///
/// C retains match-state access and table selection.  Each non-zero size is
/// paired with a validated mutable table pointer; zero-sized optional tables
/// may use null pointers.  Only the chain table receives the btlazy2 marker
/// policy.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_reduceIndex(
    hash_table: *mut u32,
    hash_size: u32,
    chain_table: *mut u32,
    chain_size: u32,
    hash_table3: *mut u32,
    hash_size3: u32,
    reducer_value: u32,
    preserve_chain_mark: c_int,
) {
    debug_assert!(!hash_table.is_null() || hash_size == 0);
    debug_assert!(!chain_table.is_null() || chain_size == 0);
    debug_assert!(!hash_table3.is_null() || hash_size3 == 0);
    debug_assert!(preserve_chain_mark == 0 || preserve_chain_mark == 1);

    unsafe {
        ZSTD_rust_reduceTable(hash_table, hash_size, reducer_value, 0);
        ZSTD_rust_reduceTable(chain_table, chain_size, reducer_value, preserve_chain_mark);
        ZSTD_rust_reduceTable(hash_table3, hash_size3, reducer_value, 0);
    }
}

/// Select the match tables participating in overflow correction and delegate
/// their cell updates to the Rust reducer.  C supplies private table pointers;
/// Rust owns the strategy, row-matchfinder, dedicated-dictionary, and marker
/// policy that determines the participating table set.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_reduceIndexForMatchState(
    hash_table: *mut u32,
    hash_log: c_uint,
    chain_table: *mut u32,
    chain_log: c_uint,
    hash_table3: *mut u32,
    hash_log3: c_uint,
    strategy: c_int,
    use_row_match_finder: c_int,
    dedicated_dict_search: c_int,
    reducer_value: c_uint,
) {
    let hash_size = 1u32.wrapping_shl(hash_log);
    let (chain_table, chain_size) = if ZSTD_rust_params_allocateChainTable(
        strategy,
        use_row_match_finder,
        dedicated_dict_search,
    ) != 0
    {
        (chain_table, 1u32.wrapping_shl(chain_log))
    } else {
        (ptr::null_mut(), 0)
    };
    let (hash_table3, hash_size3) = if hash_log3 != 0 {
        (hash_table3, 1u32.wrapping_shl(hash_log3))
    } else {
        (ptr::null_mut(), 0)
    };
    unsafe {
        ZSTD_rust_reduceIndex(
            hash_table,
            hash_size,
            chain_table,
            chain_size,
            hash_table3,
            hash_size3,
            reducer_value,
            c_int::from(strategy == ZSTD_BTLAZY2),
        );
    }
}

/// Copies a CDict match table into a CCtx, removing short-cache tags when the
/// C-owned compression parameters say the source table is tagged.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_copyCDictTableIntoCCtx(
    dst: *mut u32,
    src: *const u32,
    table_size: usize,
    tagged: c_int,
) {
    if tagged != 0 {
        for i in 0..table_size {
            let index = unsafe { *src.add(i) } >> ZSTD_SHORT_CACHE_TAG_BITS;
            unsafe { *dst.add(i) = index };
        }
    } else if table_size != 0 {
        unsafe { ptr::copy_nonoverlapping(src, dst, table_size) };
    }
}

/// Clear the previous block's repcodes before the next regular compression.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_invalidateRepCodes(rep: *mut u32) {
    debug_assert!(!rep.is_null());
    let rep = unsafe { std::slice::from_raw_parts_mut(rep, ZSTD_REP_NUM) };
    rep.fill(0);
}

/// Clear a C-owned compression window using the original `size_t`-to-`U32`
/// conversion.  The caller computes the pointer difference while the private
/// `ZSTD_window_t` layout remains entirely on the C side.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_windowClear(
    end_t: usize,
    low_limit: *mut u32,
    dict_limit: *mut u32,
) {
    debug_assert!(!low_limit.is_null());
    debug_assert!(!dict_limit.is_null());
    let end = end_t as u32;
    unsafe {
        *low_limit = end;
        *dict_limit = end;
    }
}

/// Invalidate a C-owned match-state projection after the caller computes the
/// private window pointer difference.  Rust owns the paired window-limit and
/// match-state field updates while C retains the match-state layout.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_invalidateMatchState(
    end_t: usize,
    low_limit: *mut u32,
    dict_limit: *mut u32,
    next_to_update: *mut u32,
    loaded_dict_end: *mut u32,
    lit_length_sum: *mut u32,
    dict_match_state: *mut *const c_void,
) {
    debug_assert!(!low_limit.is_null());
    debug_assert!(!dict_limit.is_null());
    debug_assert!(!next_to_update.is_null());
    debug_assert!(!loaded_dict_end.is_null());
    debug_assert!(!lit_length_sum.is_null());
    debug_assert!(!dict_match_state.is_null());
    unsafe {
        ZSTD_rust_windowClear(end_t, low_limit, dict_limit);
        *next_to_update = *dict_limit;
        *loaded_dict_end = 0;
        *lit_length_sum = 0;
        *dict_match_state = ptr::null();
    }
}

const HASH_READ_SIZE: u32 = 8;

/// Private C window fields projected for the shared window-update policy.
/// Pointer arithmetic is intentionally performed as wrapping address math to
/// mirror the original C implementation's pointer-overflow contract.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_rust_windowUpdateState {
    pub nextSrc: *const c_void,
    pub base: *const c_void,
    pub dictBase: *const c_void,
    pub dictLimit: u32,
    pub lowLimit: u32,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_windowUpdateState, nextSrc) == 0);
    assert!(offset_of!(ZSTD_rust_windowUpdateState, base) == size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_windowUpdateState, dictBase) == 2 * size_of::<usize>());
    assert!(offset_of!(ZSTD_rust_windowUpdateState, dictLimit) == 3 * size_of::<usize>());
    assert!(
        offset_of!(ZSTD_rust_windowUpdateState, lowLimit)
            == 3 * size_of::<usize>() + size_of::<u32>()
    );
    assert!(
        size_of::<ZSTD_rust_windowUpdateState>() == 3 * size_of::<usize>() + 2 * size_of::<u32>()
    );
};

static WINDOW_INIT_SENTINEL: [u8; 2] = [b' ', 0];

/// Initialize the projected window fields. C retains the containing object
/// and its overflow-correction counter.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_windowInit(state: *mut ZSTD_rust_windowUpdateState) {
    if state.is_null() {
        return;
    }
    let base = WINDOW_INIT_SENTINEL.as_ptr();
    unsafe {
        *state = ZSTD_rust_windowUpdateState {
            nextSrc: base.wrapping_add(2).cast(),
            base: base.cast(),
            dictBase: base.cast(),
            dictLimit: ZSTD_WINDOW_START_INDEX,
            lowLimit: ZSTD_WINDOW_START_INDEX,
        };
    }
}

#[no_mangle]
pub extern "C" fn ZSTD_rust_windowIsEmpty(
    next_src: *const c_void,
    base: *const c_void,
    dict_limit: u32,
    low_limit: u32,
) -> c_uint {
    (dict_limit == ZSTD_WINDOW_START_INDEX
        && low_limit == ZSTD_WINDOW_START_INDEX
        && (next_src as usize).wrapping_sub(base as usize) == ZSTD_WINDOW_START_INDEX as usize)
        as c_uint
}

#[no_mangle]
pub extern "C" fn ZSTD_rust_windowHasExtDict(dict_limit: u32, low_limit: u32) -> c_uint {
    (low_limit < dict_limit) as c_uint
}

/// Project the dictionary/window limit policy while C retains pointer-owned
/// match-state invalidation and the private window layout.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_rust_windowDictState {
    pub lowLimit: u32,
    pub dictLimit: u32,
    pub loadedDictEnd: u32,
    pub invalidate: u32,
}

const _: () = {
    assert!(offset_of!(ZSTD_rust_windowDictState, lowLimit) == 0);
    assert!(offset_of!(ZSTD_rust_windowDictState, dictLimit) == size_of::<u32>());
    assert!(offset_of!(ZSTD_rust_windowDictState, loadedDictEnd) == 2 * size_of::<u32>());
    assert!(offset_of!(ZSTD_rust_windowDictState, invalidate) == 3 * size_of::<u32>());
    assert!(size_of::<ZSTD_rust_windowDictState>() == 4 * size_of::<u32>());
};

#[no_mangle]
pub extern "C" fn ZSTD_rust_windowEnforceMaxDist(
    block_end_idx: u32,
    max_dist: u32,
    mut state: ZSTD_rust_windowDictState,
) -> ZSTD_rust_windowDictState {
    state.invalidate = 0;
    if block_end_idx > max_dist.wrapping_add(state.loadedDictEnd) {
        let new_low_limit = block_end_idx.wrapping_sub(max_dist);
        if state.lowLimit < new_low_limit {
            state.lowLimit = new_low_limit;
        }
        if state.dictLimit < state.lowLimit {
            state.dictLimit = state.lowLimit;
        }
        state.loadedDictEnd = 0;
        state.invalidate = 1;
    }
    state
}

#[no_mangle]
pub extern "C" fn ZSTD_rust_windowCheckDictValidity(
    block_end_idx: u32,
    max_dist: u32,
    loaded_dict_end: u32,
    dict_limit: u32,
) -> c_uint {
    (block_end_idx > loaded_dict_end.wrapping_add(max_dist) || loaded_dict_end != dict_limit)
        as c_uint
}

/// Update the rolling prefix/ext-dictionary window for one input segment.
/// C owns the containing match state; Rust owns this five-field transition.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_windowUpdate(
    state: *mut ZSTD_rust_windowUpdateState,
    src: *const c_void,
    src_size: usize,
    force_non_contiguous: c_int,
) -> c_uint {
    if state.is_null() {
        return 1;
    }
    let state = unsafe { &mut *state };
    if src_size == 0 {
        return 1;
    }

    debug_assert!(!state.base.is_null());
    debug_assert!(!state.dictBase.is_null());

    let ip = src as usize;
    let input_end = ip.wrapping_add(src_size);
    let mut contiguous = 1;
    if ip != state.nextSrc as usize || force_non_contiguous != 0 {
        let distance_from_base = (state.nextSrc as usize).wrapping_sub(state.base as usize);
        state.lowLimit = state.dictLimit;
        debug_assert!(distance_from_base <= u32::MAX as usize);
        state.dictLimit = distance_from_base as u32;
        state.dictBase = state.base;
        state.base = ip.wrapping_sub(distance_from_base) as *const c_void;
        if state.dictLimit.wrapping_sub(state.lowLimit) < HASH_READ_SIZE {
            state.lowLimit = state.dictLimit;
        }
        contiguous = 0;
    }

    state.nextSrc = input_end as *const c_void;
    let dict_base = state.dictBase as usize;
    if input_end > dict_base.wrapping_add(state.lowLimit as usize)
        && ip < dict_base.wrapping_add(state.dictLimit as usize)
    {
        let high_input_idx = input_end.wrapping_sub(dict_base);
        debug_assert!(high_input_idx < u32::MAX as usize);
        let low_limit_max = if high_input_idx > state.dictLimit as usize {
            state.dictLimit
        } else {
            high_input_idx as u32
        };
        state.lowLimit = low_limit_max;
    }
    contiguous
}

#[inline]
fn set_pledged_src_size(
    stream_stage: c_int,
    pledged_src_size: u64,
    pledged_src_size_plus_one: *mut u64,
) -> usize {
    if stream_stage != ZSTD_CSTREAM_STAGE_INIT {
        return ERROR(ZstdErrorCode::StageWrong);
    }
    debug_assert!(!pledged_src_size_plus_one.is_null());
    unsafe {
        *pledged_src_size_plus_one = pledged_src_size.wrapping_add(1);
    }
    0
}

/// Set the pledged source size through scalar stage state and a C-owned field.
/// The stage error remains the public `stage_wrong` encoding, while the
/// unsigned increment preserves C's defined wrap at `U64::MAX`.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_setPledgedSrcSize(
    stream_stage: c_int,
    pledged_src_size: u64,
    pledged_src_size_plus_one: *mut u64,
) -> usize {
    set_pledged_src_size(stream_stage, pledged_src_size, pledged_src_size_plus_one)
}

#[inline]
fn zeroed_state() -> ZSTD_compressedBlockState_t {
    /* The state contains only integer arrays and enum fields. */
    unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() }
}

#[inline]
fn checked_table_size(log: u32) -> Option<usize> {
    1usize.checked_shl(log)
}

#[inline]
fn ceil_log2(size: usize) -> u32 {
    if size <= 1 {
        0
    } else {
        usize::BITS - (size - 1).leading_zeros()
    }
}

#[inline]
unsafe fn write_empty_sequence_block(dst: *mut u8, dst_capacity: usize) -> usize {
    /* Keep the original C helper's four-byte write and capacity check. */
    if dst_capacity < 4 {
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }
    let header = 1u32.to_le_bytes();
    unsafe { ptr::copy_nonoverlapping(header.as_ptr(), dst, header.len()) };
    ZSTD_BLOCK_HEADER_SIZE
}

/// Rust implementation of the per-block loop from
/// `ZSTD_compressSequences_internal()`.
///
/// Public initialization, frame-header/checksum ordering, and validation are
/// driven by the Rust API orchestrator below.  The projected state keeps the
/// ABI explicit while allowing this loop to reuse the existing Rust
/// sequence-transfer, entropy, and block-serialization leaves.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressSequencesInternal(
    state: *const ZSTD_rust_sequenceCompressionState,
    dst: *mut c_void,
    dst_capacity: usize,
    in_seqs: *const ZSTD_Sequence,
    in_seqs_size: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.seq_store.is_null()
        || state.prev_c_block.is_null()
        || state.next_c_block.is_null()
        || state.is_first_block.is_null()
    {
        return ERROR(ZstdErrorCode::Generic);
    }
    if unsafe { (*state.prev_c_block).is_null() || (*state.next_c_block).is_null() } {
        return ERROR(ZstdErrorCode::Generic);
    }

    let mut c_size = 0usize;
    let mut remaining = src_size;
    let mut seq_pos = ZSTD_SequencePosition::default();
    let mut ip = src.cast::<u8>();
    let mut op = dst.cast::<u8>();
    let mut dst_capacity = dst_capacity;
    let explicit_delimiters =
        ZSTD_rust_selectSequenceCopier(state.block_delimiters) == ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS;

    /* Special case: empty frame. */
    if remaining == 0 {
        return unsafe { write_empty_sequence_block(op, dst_capacity) };
    }

    while remaining != 0 {
        let mut block_size = unsafe {
            ZSTD_rust_determineBlockSize(
                state.block_delimiters,
                state.block_size_max,
                remaining,
                in_seqs,
                in_seqs_size,
                seq_pos.idx,
            )
        };
        let last_block = u32::from(block_size == remaining);
        if ERR_isError(block_size) {
            return block_size;
        }
        debug_assert!(block_size <= remaining);

        unsafe { ZSTD_rust_resetSeqStore(state.seq_store) };

        let prev_block = unsafe { *state.prev_c_block };
        let next_block = unsafe { *state.next_c_block };
        block_size = if explicit_delimiters {
            unsafe {
                ZSTD_rust_transferSequencesWBlockDelim(
                    state.seq_store,
                    &mut seq_pos,
                    in_seqs,
                    in_seqs_size,
                    ip,
                    block_size,
                    state.search_for_external_repcodes,
                    (*prev_block).rep.as_ptr(),
                    (*next_block).rep.as_mut_ptr(),
                    state.dict_size,
                    state.validate_sequences,
                    state.min_match,
                    state.window_log,
                    state.use_sequence_producer,
                )
            }
        } else {
            unsafe {
                ZSTD_rust_transferSequencesNoDelim(
                    state.seq_store,
                    &mut seq_pos,
                    in_seqs,
                    in_seqs_size,
                    ip,
                    block_size,
                    (*prev_block).rep.as_ptr(),
                    (*next_block).rep.as_mut_ptr(),
                    state.dict_size,
                    state.validate_sequences,
                    state.min_match,
                    state.window_log,
                    state.use_sequence_producer,
                )
            }
        };
        if ERR_isError(block_size) {
            return block_size;
        }

        /* If blocks are too small, emit as a nocompress block. */
        if block_size < MIN_COMPRESSIBLE_BLOCK_SIZE {
            let c_block_size = unsafe {
                ZSTD_rust_noCompressBlock(
                    op.cast(),
                    dst_capacity,
                    ip.cast(),
                    block_size,
                    last_block,
                )
            };
            if ERR_isError(c_block_size) {
                return c_block_size;
            }
            c_size = c_size.wrapping_add(c_block_size);
            unsafe {
                ip = ip.add(block_size);
                op = op.add(c_block_size);
            }
            remaining -= block_size;
            dst_capacity -= c_block_size;
            continue;
        }

        if dst_capacity < ZSTD_BLOCK_HEADER_SIZE {
            return ERROR(ZstdErrorCode::DstSizeTooSmall);
        }

        let compressed_size = unsafe {
            ZSTD_rust_entropyCompressSeqStore(
                state.seq_store,
                ptr::addr_of!((*prev_block).entropy),
                ptr::addr_of_mut!((*next_block).entropy),
                state.strategy,
                state.disable_literal_compression,
                op.add(ZSTD_BLOCK_HEADER_SIZE).cast(),
                dst_capacity - ZSTD_BLOCK_HEADER_SIZE,
                block_size,
                state.tmp_workspace,
                state.tmp_wksp_size,
                state.bmi2,
            )
        };
        if ERR_isError(compressed_size) {
            return compressed_size;
        }

        let is_first_block = unsafe { *state.is_first_block };
        let (maybe_rle, is_rle) = if is_first_block == 0 {
            let maybe_rle = unsafe { ZSTD_rust_maybeRLE(state.seq_store) };
            let is_rle = if maybe_rle != 0 {
                unsafe { ZSTD_rust_isRLE(ip, block_size) }
            } else {
                0
            };
            (maybe_rle, is_rle)
        } else {
            (0, 0)
        };
        let action = sequence_block_action(is_first_block, maybe_rle, is_rle, compressed_size);

        let c_block_size = match action {
            SequenceBlockAction::Raw => unsafe {
                /* ZSTD_noCompressBlock writes the block header as well. */
                ZSTD_rust_noCompressBlock(
                    op.cast(),
                    dst_capacity,
                    ip.cast(),
                    block_size,
                    last_block,
                )
            },
            SequenceBlockAction::Rle => unsafe {
                ZSTD_rust_rleCompressBlock(op.cast(), dst_capacity, *ip, block_size, last_block)
            },
            SequenceBlockAction::Compressed => {
                /* Error checking and repcodes update. */
                unsafe {
                    ZSTD_rust_confirmRepcodesAndEntropyTables(
                        state.prev_c_block,
                        state.next_c_block,
                    );
                }
                let prev_block = unsafe { *state.prev_c_block };
                if unsafe { (*prev_block).entropy.fse.offcode_repeatMode } == 2 {
                    unsafe { (*prev_block).entropy.fse.offcode_repeatMode = 1 };
                }

                unsafe {
                    ZSTD_rust_writeBlockHeader(op.cast(), compressed_size, block_size, last_block)
                };
                ZSTD_BLOCK_HEADER_SIZE + compressed_size
            }
        };
        if ERR_isError(c_block_size) {
            return c_block_size;
        }

        c_size = c_size.wrapping_add(c_block_size);
        if last_block != 0 {
            break;
        }

        unsafe {
            ip = ip.add(block_size);
            op = op.add(c_block_size);
            *state.is_first_block = 0;
        }
        remaining -= block_size;
        dst_capacity -= c_block_size;
    }

    c_size
}

/// Compress one frame using the already migrated block leaves.
///
/// This path owns the match tables and carries their history across the
/// 128 KiB block boundaries, while keeping the private C
/// `ZSTD_MatchState_t` window out of the Rust ABI.
/// Writes the three-byte raw header used by the external
/// sequences-and-literals empty-frame special case.
#[inline]
unsafe fn write_empty_sequence_literals_block(dst: *mut u8, dst_capacity: usize) -> usize {
    if dst_capacity < ZSTD_BLOCK_HEADER_SIZE {
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }
    let header = [1u8, 0, 0];
    unsafe { ptr::copy_nonoverlapping(header.as_ptr(), dst, header.len()) };
    ZSTD_BLOCK_HEADER_SIZE
}

/// Rust implementation of the block loop from
/// ZSTD_compressSequencesAndLiterals_internal.
///
/// The C wrapper retains the private CCtx-dependent state and sequence
/// conversion callback. Rust owns the public validation/ordering layer, the
/// external literal cursor, per-block entropy pass, compressed-block framing,
/// and completion checks.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressSequencesAndLiteralsInternal(
    state: *const ZSTD_rust_sequenceLiteralsState,
    dst: *mut c_void,
    dst_capacity: usize,
    in_seqs: *const ZSTD_Sequence,
    nb_sequences: usize,
    literals: *const c_void,
    lit_size: usize,
    src_size: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &*state };
    if state.seq_store.is_null()
        || state.prev_c_block.is_null()
        || state.next_c_block.is_null()
        || state.is_first_block.is_null()
        || unsafe { (*state.prev_c_block).is_null() || (*state.next_c_block).is_null() }
    {
        return ERROR(ZstdErrorCode::Generic);
    }
    if nb_sequences == 0 {
        return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
    }

    let mut remaining = src_size;
    let mut nb_sequences = nb_sequences;
    let mut c_size = 0usize;
    let mut op = dst.cast::<u8>();
    let mut dst_capacity = dst_capacity;
    let mut in_seqs = in_seqs;
    let mut literals = literals;
    let mut lit_size = lit_size;

    /* Special case: empty frame. Keep the C ordering: this header is emitted
     * before the ordinary sequence loop. */
    if nb_sequences == 1 && unsafe { (*in_seqs).litLength } == 0 {
        let written = unsafe { write_empty_sequence_literals_block(op, dst_capacity) };
        if ERR_isError(written) {
            return written;
        }
        unsafe {
            op = op.add(written);
        }
        dst_capacity -= written;
        c_size += written;
    }

    while nb_sequences != 0 {
        let block = unsafe { ZSTD_rust_get1BlockSummary(in_seqs, nb_sequences) };
        let last_block = c_uint::from(block.nbSequences == nb_sequences);
        if ERR_isError(block.nbSequences) {
            return block.nbSequences;
        }
        debug_assert!(block.nbSequences <= nb_sequences);
        if block.litSize > lit_size {
            return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
        }

        unsafe { ZSTD_rust_resetSeqStore(state.seq_store) };
        let conversion_status = unsafe {
            (state.convert_block_sequences)(
                state.callback_context,
                in_seqs,
                block.nbSequences,
                state.repcode_resolution,
            )
        };
        if ERR_isError(conversion_status) {
            return conversion_status;
        }

        unsafe {
            in_seqs = in_seqs.add(block.nbSequences);
        }
        nb_sequences -= block.nbSequences;
        remaining = remaining.wrapping_sub(block.blockSize);

        if dst_capacity < ZSTD_BLOCK_HEADER_SIZE {
            return ERROR(ZstdErrorCode::DstSizeTooSmall);
        }

        let prev_block = unsafe { *state.prev_c_block };
        let next_block = unsafe { *state.next_c_block };
        if prev_block.is_null() || next_block.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        let compressed_size = unsafe {
            ZSTD_rust_entropyCompressSeqStore_internal(
                op.add(ZSTD_BLOCK_HEADER_SIZE).cast(),
                dst_capacity - ZSTD_BLOCK_HEADER_SIZE,
                literals,
                block.litSize,
                state.seq_store,
                ptr::addr_of!((*prev_block).entropy),
                ptr::addr_of_mut!((*next_block).entropy),
                state.strategy,
                state.disable_literal_compression,
                state.tmp_workspace,
                state.tmp_wksp_size,
                state.bmi2,
            )
        };
        if ERR_isError(compressed_size) {
            return compressed_size;
        }

        let compressed_size = if compressed_size > state.block_size_max {
            0
        } else {
            compressed_size
        };
        unsafe {
            literals = literals.cast::<u8>().add(block.litSize).cast();
        }
        lit_size = lit_size.wrapping_sub(block.litSize);

        if compressed_size == 0 {
            return ERROR(ZstdErrorCode::CannotProduceUncompressedBlock);
        }

        debug_assert!(compressed_size > 1);
        unsafe {
            ZSTD_rust_confirmRepcodesAndEntropyTables(state.prev_c_block, state.next_c_block);
        }
        let prev_block = unsafe { *state.prev_c_block };
        if prev_block.is_null() {
            return ERROR(ZstdErrorCode::Generic);
        }
        if unsafe { (*prev_block).entropy.fse.offcode_repeatMode } == 2 {
            unsafe { (*prev_block).entropy.fse.offcode_repeatMode = 1 };
        }

        unsafe {
            ZSTD_rust_writeBlockHeader(op.cast(), compressed_size, block.blockSize, last_block);
        }
        let c_block_size = ZSTD_BLOCK_HEADER_SIZE + compressed_size;
        c_size = c_size.wrapping_add(c_block_size);
        unsafe {
            op = op.add(c_block_size);
            *state.is_first_block = 0;
        }
        dst_capacity = dst_capacity.wrapping_sub(c_block_size);

        if last_block != 0 {
            break;
        }
    }

    if lit_size != 0 || remaining != 0 {
        return ERROR(ZstdErrorCode::ExternalSequencesInvalid);
    }
    c_size
}

unsafe fn sequence_api_prepare(
    state: &mut ZSTD_rust_sequenceApiState,
    pledged_src_size: usize,
    with_literals: bool,
    lit_size: usize,
    lit_capacity: usize,
) -> Result<SequenceApiPlan, usize> {
    if with_literals {
        let capacity_result = sequence_api_validate_literal_capacity(lit_size, lit_capacity);
        if ERR_isError(capacity_result) {
            return Err(capacity_result);
        }
    }

    if state.callback_context.is_null()
        || state.sequence_state.is_null()
        || state.sequence_literals_state.is_null()
        || state.init as usize == 0
        || state.checksum_state.is_null()
    {
        return Err(ERROR(ZstdErrorCode::Generic));
    }

    let init_result = unsafe {
        (state.init)(
            state.callback_context,
            pledged_src_size,
            state as *mut ZSTD_rust_sequenceApiState,
        )
    };
    if ERR_isError(init_result) {
        return Err(init_result);
    }

    sequence_api_plan(
        with_literals,
        state.block_delimiters,
        state.validate_sequences,
        state.checksum_flag,
    )
}

unsafe fn sequence_api_write_frame_header(
    state: &ZSTD_rust_sequenceApiState,
    op: &mut *mut u8,
    dst_capacity: &mut usize,
    c_size: &mut usize,
    pledged_src_size: usize,
) -> usize {
    let frame_header_size = unsafe {
        ZSTD_rust_writeFrameHeader(
            (*op).cast(),
            *dst_capacity,
            state.no_dict_id_flag,
            state.checksum_flag,
            state.content_size_flag,
            state.format,
            state.window_log,
            pledged_src_size as u64,
            state.dict_id,
        )
    };
    if ERR_isError(frame_header_size) {
        return frame_header_size;
    }
    if frame_header_size > *dst_capacity {
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }

    unsafe {
        *op = (*op).add(frame_header_size);
    }
    *dst_capacity -= frame_header_size;
    *c_size = c_size.wrapping_add(frame_header_size);
    0
}

unsafe fn sequence_api_append_frame_checksum(
    state: &ZSTD_rust_sequenceApiState,
    plan: SequenceApiPlan,
    op: *mut u8,
    dst_capacity: usize,
    c_size: &mut usize,
) -> usize {
    if !plan.append_frame_checksum {
        return 0;
    }

    /* Keep the original ordering: digest the checksum before checking the
     * remaining destination capacity. */
    let checksum = unsafe { XXH64_digest(state.checksum_state) as c_uint };
    if dst_capacity < 4 {
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }
    unsafe { MEM_writeLE32(op.cast(), checksum) };
    *c_size = c_size.wrapping_add(4);
    0
}

/// Rust-owned orchestration for `ZSTD_compressSequences`.
///
/// The C wrapper provides the post-initialization block-state projection and
/// callback for private CCtx initialization; frame-header fields and the
/// checksum state are projected directly.  Rust preserves the public ordering:
/// initialize, write the frame header, update the input checksum, emit blocks,
/// then append the frame checksum.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressSequences(
    state: *mut ZSTD_rust_sequenceApiState,
    dst: *mut c_void,
    dst_capacity: usize,
    in_seqs: *const ZSTD_Sequence,
    in_seqs_size: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &mut *state };
    let plan = match unsafe { sequence_api_prepare(state, src_size, false, 0, 0) } {
        Ok(plan) => plan,
        Err(result) => return result,
    };

    let mut op = dst.cast::<u8>();
    let mut dst_capacity = dst_capacity;
    let mut c_size = 0usize;
    let header_result = unsafe {
        sequence_api_write_frame_header(state, &mut op, &mut dst_capacity, &mut c_size, src_size)
    };
    if ERR_isError(header_result) {
        return header_result;
    }

    if plan.update_input_checksum && src_size != 0 {
        unsafe {
            let _ = XXH64_update(state.checksum_state, src, src_size);
        }
    }

    let block_size = unsafe {
        ZSTD_rust_compressSequencesInternal(
            &*state.sequence_state,
            op.cast(),
            dst_capacity,
            in_seqs,
            in_seqs_size,
            src,
            src_size,
        )
    };
    if ERR_isError(block_size) {
        return block_size;
    }
    if block_size > dst_capacity {
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }
    unsafe {
        op = op.add(block_size);
    }
    dst_capacity -= block_size;
    c_size = c_size.wrapping_add(block_size);

    let checksum_result =
        unsafe { sequence_api_append_frame_checksum(state, plan, op, dst_capacity, &mut c_size) };
    if ERR_isError(checksum_result) {
        return checksum_result;
    }

    c_size
}

/// Rust-owned orchestration for `ZSTD_compressSequencesAndLiterals`.
///
/// The literal-capacity check intentionally precedes CCtx initialization, and
/// the post-initialization incompatibility checks retain their original
/// precedence.  The existing Rust block loop remains responsible for literal
/// accounting, sequence conversion, and block codec operations.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressSequencesAndLiterals(
    state: *mut ZSTD_rust_sequenceApiState,
    dst: *mut c_void,
    dst_capacity: usize,
    in_seqs: *const ZSTD_Sequence,
    in_seqs_size: usize,
    literals: *const c_void,
    lit_size: usize,
    lit_capacity: usize,
    decompressed_size: usize,
) -> usize {
    if state.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    let state = unsafe { &mut *state };
    let plan = match unsafe {
        sequence_api_prepare(state, decompressed_size, true, lit_size, lit_capacity)
    } {
        Ok(plan) => plan,
        Err(result) => return result,
    };

    let mut op = dst.cast::<u8>();
    let mut dst_capacity = dst_capacity;
    let mut c_size = 0usize;
    let header_result = unsafe {
        sequence_api_write_frame_header(
            state,
            &mut op,
            &mut dst_capacity,
            &mut c_size,
            decompressed_size,
        )
    };
    if ERR_isError(header_result) {
        return header_result;
    }

    let block_size = unsafe {
        ZSTD_rust_compressSequencesAndLiteralsInternal(
            &*state.sequence_literals_state,
            op.cast(),
            dst_capacity,
            in_seqs,
            in_seqs_size,
            literals,
            lit_size,
            decompressed_size,
        )
    };
    if ERR_isError(block_size) {
        return block_size;
    }
    if block_size > dst_capacity {
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }
    dst_capacity -= block_size;
    c_size = c_size.wrapping_add(block_size);

    let checksum_result =
        unsafe { sequence_api_append_frame_checksum(state, plan, op, dst_capacity, &mut c_size) };
    if ERR_isError(checksum_result) {
        return checksum_result;
    }

    c_size
}

unsafe fn compress_frame(
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    compression_level: c_int,
) -> usize {
    if dst.is_null() {
        return ERROR(if dst_capacity == 0 {
            ZstdErrorCode::DstSizeTooSmall
        } else {
            ZstdErrorCode::DstBufferNull
        });
    }
    if src_size != 0 && src.is_null() {
        return ERROR(ZstdErrorCode::SrcSizeWrong);
    }
    if src_size as u64 == ZSTD_CONTENTSIZE_UNKNOWN {
        return ERROR(ZstdErrorCode::SrcSizeWrong);
    }

    let mut cparams = ZSTD_rust_params_selectCParams(
        compression_level,
        src_size as u64,
        0,
        ZSTD_RUST_CPM_NO_ATTACH_DICT,
    );
    cparams = ZSTD_rust_params_adjustCParams(
        cparams,
        src_size as u64,
        0,
        ZSTD_RUST_CPM_NO_ATTACH_DICT,
        ZSTD_RUST_PS_DISABLE,
    );

    let header_size = unsafe {
        ZSTD_rust_writeFrameHeader(
            dst,
            dst_capacity,
            0, /* noDictIDFlag */
            0, /* checksumFlag */
            1, /* contentSizeFlag */
            0, /* zstd frame */
            cparams.windowLog,
            src_size as u64,
            0,
        )
    };
    if ERR_isError(header_size) {
        return header_size;
    }

    if src_size == 0 {
        let empty_block = unsafe {
            ZSTD_writeLastEmptyBlock(
                dst.cast::<u8>().add(header_size).cast(),
                dst_capacity - header_size,
            )
        };
        return if ERR_isError(empty_block) {
            empty_block
        } else {
            header_size + empty_block
        };
    }

    let first_block_size = src_size.min(ZSTD_BLOCKSIZE_MAX);
    let matcher_hash_log = cparams.hashLog;
    let matcher_chain_log = cparams.chainLog.min(ceil_log2(first_block_size).max(6));
    let hash_size = match checked_table_size(matcher_hash_log) {
        Some(size) => size,
        None => return ERROR(ZstdErrorCode::MemoryAllocation),
    };
    let chain_size = match checked_table_size(matcher_chain_log) {
        Some(size) => size,
        None => return ERROR(ZstdErrorCode::MemoryAllocation),
    };

    let max_nb_seq =
        ZSTD_rust_params_maxNbSeq(ZSTD_BLOCKSIZE_MAX, cparams.minMatch, 0).saturating_add(1);
    let disable_literal_compression =
        c_int::from(cparams.strategy == ZSTD_FAST && cparams.targetLength > 0);
    let mut sequences = vec![SeqDef::default(); max_nb_seq];
    let mut literals = vec![0u8; ZSTD_BLOCKSIZE_MAX];
    let mut ll_codes = vec![0u8; max_nb_seq];
    let mut ml_codes = vec![0u8; max_nb_seq];
    let mut of_codes = vec![0u8; max_nb_seq];
    let mut hash_table = vec![0u32; hash_size];
    let mut chain_table = vec![0u32; chain_size];
    let mut workspace = vec![0u64; TMP_WORKSPACE_SIZE / size_of::<u64>()];
    let mut prev_block = zeroed_state();
    let mut next_block = zeroed_state();
    prev_block.rep = [1, 4, 8];
    next_block.rep = prev_block.rep;

    let seq_store = &mut SeqStore_t {
        sequencesStart: sequences.as_mut_ptr(),
        sequences: sequences.as_mut_ptr(),
        litStart: literals.as_mut_ptr(),
        lit: literals.as_mut_ptr(),
        llCode: ll_codes.as_mut_ptr(),
        mlCode: ml_codes.as_mut_ptr(),
        ofCode: of_codes.as_mut_ptr(),
        maxNbSeq: max_nb_seq,
        maxNbLit: ZSTD_BLOCKSIZE_MAX,
        longLengthType: 0,
        longLengthPos: 0,
    };

    let source = src.cast::<u8>();
    let output = dst.cast::<u8>();
    let matcher_base = source.wrapping_sub(ZSTD_WINDOW_START_INDEX as usize);
    let mut input_offset = 0usize;
    let mut output_offset = header_size;
    while input_offset < src_size {
        let block_size = (src_size - input_offset).min(ZSTD_BLOCKSIZE_MAX);
        let block_src = unsafe { source.add(input_offset) };
        let block_end = unsafe { block_src.add(block_size) };
        let last_block = u32::from(input_offset + block_size == src_size);

        if block_size < MIN_COMPRESSIBLE_BLOCK_SIZE {
            let written = unsafe {
                write_raw_block(
                    output.add(output_offset),
                    dst_capacity.saturating_sub(output_offset),
                    block_src,
                    block_size,
                    last_block,
                )
            };
            if ERR_isError(written) {
                return written;
            }
            output_offset += written;
            input_offset += block_size;
            continue;
        }

        seq_store.sequences = seq_store.sequencesStart;
        seq_store.lit = seq_store.litStart;
        seq_store.longLengthType = 0;
        seq_store.longLengthPos = 0;
        next_block.rep = prev_block.rep;

        let mut reps = prev_block.rep;
        let last_literals = if block_size < 8 {
            block_size
        } else if cparams.strategy == ZSTD_DFAST {
            unsafe {
                crate::zstd_double_fast::ZSTD_rust_compressBlock_doubleFast(
                    hash_table.as_mut_ptr(),
                    chain_table.as_mut_ptr(),
                    matcher_base,
                    ZSTD_WINDOW_START_INDEX,
                    0,
                    matcher_hash_log,
                    matcher_chain_log,
                    cparams.minMatch,
                    cparams.windowLog,
                    (seq_store as *mut SeqStore_t).cast(),
                    reps.as_mut_ptr(),
                    block_src.cast(),
                    block_size,
                )
            }
        } else {
            unsafe {
                crate::zstd_fast::ZSTD_rust_compressBlock_fast(
                    hash_table.as_mut_ptr(),
                    matcher_base,
                    ZSTD_WINDOW_START_INDEX,
                    0,
                    matcher_hash_log,
                    cparams.minMatch,
                    cparams.targetLength,
                    cparams.windowLog,
                    (seq_store as *mut SeqStore_t).cast(),
                    reps.as_mut_ptr(),
                    block_src.cast(),
                    block_size,
                )
            }
        };

        if last_literals > block_size {
            return ERROR(ZstdErrorCode::Generic);
        }
        let last_literal_src = unsafe { block_end.sub(last_literals) };
        if last_literals != 0 {
            unsafe {
                ptr::copy_nonoverlapping(last_literal_src, seq_store.lit, last_literals);
                seq_store.lit = seq_store.lit.add(last_literals);
            }
        }
        let remaining_capacity = dst_capacity.saturating_sub(output_offset);
        if remaining_capacity < ZSTD_BLOCK_HEADER_SIZE {
            return ERROR(ZstdErrorCode::DstSizeTooSmall);
        }
        let mut compressed_size = unsafe {
            ZSTD_rust_entropyCompressSeqStore(
                (seq_store as *const SeqStore_t).cast(),
                ptr::addr_of!(prev_block.entropy),
                ptr::addr_of_mut!(next_block.entropy),
                cparams.strategy,
                disable_literal_compression,
                output.add(output_offset + ZSTD_BLOCK_HEADER_SIZE).cast(),
                remaining_capacity - ZSTD_BLOCK_HEADER_SIZE,
                block_size,
                workspace.as_mut_ptr().cast(),
                TMP_WORKSPACE_SIZE,
                0, /* BMI2 is optional; portable Rust leaf path */
            )
        };
        if ERR_isError(compressed_size) {
            return compressed_size;
        }
        if input_offset != 0
            && compressed_size < 25
            && unsafe { ZSTD_rust_isRLE(block_src, block_size) } != 0
        {
            unsafe {
                *output.add(output_offset + ZSTD_BLOCK_HEADER_SIZE) = *block_src;
            }
            compressed_size = 1;
        }

        let written = if compressed_size == 0 {
            unsafe {
                write_raw_block(
                    output.add(output_offset),
                    remaining_capacity,
                    block_src,
                    block_size,
                    last_block,
                )
            }
        } else {
            unsafe {
                ZSTD_rust_writeBlockHeader(
                    output.add(output_offset).cast(),
                    compressed_size,
                    block_size,
                    last_block,
                )
            };
            if compressed_size > 1 {
                next_block.rep = reps;
            }
            compressed_size + ZSTD_BLOCK_HEADER_SIZE
        };
        if ERR_isError(written) {
            return written;
        }
        output_offset += written;
        input_offset += block_size;
        if compressed_size > 1 {
            std::mem::swap(&mut prev_block, &mut next_block);
        }
    }

    output_offset
}

/// Select the complete-input streaming fast path before invoking the C-owned
/// simple-level predicate. Rust owns the stream-state branch; C keeps the
/// private context and level-selection leaf behind a callback.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_simpleCompressStream2Policy(
    projection: *const ZSTD_rust_simpleCompressStream2Projection,
    cctx: *const c_void,
    src_size: usize,
    simple_compress2_level: Option<ZSTD_rust_simpleCompress2LevelFn>,
) -> c_int {
    let Some(projection) = (unsafe { projection.as_ref() }) else {
        return c_int::MIN;
    };
    if cctx.is_null()
        || projection.stream_stage != ZSTD_CSTREAM_STAGE_INIT
        || projection.pledged_src_size_plus_one != 0
        || projection.rust_simple_compress2_completed != 0
    {
        return c_int::MIN;
    }
    let Some(simple_compress2_level) = simple_compress2_level else {
        return c_int::MIN;
    };
    unsafe { simple_compress2_level(cctx, src_size) }
}

/// Simple one-shot compression entry point.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_compress(
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    compression_level: c_int,
) -> usize {
    #[cfg(not(test))]
    {
        let strategy = ZSTD_rust_compressCCtxStrategy(src_size, compression_level);
        if strategy != ZSTD_FAST && strategy != ZSTD_DFAST {
            let cctx = unsafe { ZSTD_createCCtx() };
            if cctx.is_null() {
                return ERROR(ZstdErrorCode::MemoryAllocation);
            }
            let result = unsafe {
                ZSTD_compress_usingDict(
                    cctx,
                    dst,
                    dst_capacity,
                    src,
                    src_size,
                    ptr::null(),
                    0,
                    compression_level,
                )
            };
            unsafe { ZSTD_freeCCtx(cctx) };
            return result;
        }
    }
    unsafe { compress_frame(dst, dst_capacity, src, src_size, compression_level) }
}

/// Simple explicit-context compression entry point.
///
/// The public contract deliberately ignores all advanced context parameters.
/// C performs the context reset because the private `ZSTD_CCtx_s` layout is
/// still configuration-dependent.  Strategies not yet implemented by the
/// Rust frame compressor use the original C simple API before that reset.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_compressCCtx(
    cctx: *mut c_void,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
    compression_level: c_int,
) -> usize {
    if cctx.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }
    #[cfg(not(test))]
    {
        let strategy = ZSTD_rust_compressCCtxStrategy(src_size, compression_level);
        if strategy != ZSTD_FAST && strategy != ZSTD_DFAST {
            return unsafe {
                ZSTD_compress_usingDict(
                    cctx,
                    dst,
                    dst_capacity,
                    src,
                    src_size,
                    ptr::null(),
                    0,
                    compression_level,
                )
            };
        }
        let reset = unsafe { ZSTD_rust_resetCCtxForSimpleCompression(cctx) };
        if ERR_isError(reset) {
            return reset;
        }
        let prepare =
            unsafe { ZSTD_rust_prepareCCtxForSimpleCompression(cctx, src_size, compression_level) };
        if ERR_isError(prepare) {
            return prepare;
        }
    }
    unsafe { compress_frame(dst, dst_capacity, src, src_size, compression_level) }
}

/// Stateful compression entry point during the context migration.
///
/// A context with only the ordinary frame settings is reset by the C shim and
/// compressed through the Rust frame path.  Contexts using dictionaries,
/// checksums, target-sized blocks, sequence collection, or other advanced
/// state still use the renamed C implementation until their state is moved.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_compress2(
    cctx: *mut c_void,
    dst: *mut c_void,
    dst_capacity: usize,
    src: *const c_void,
    src_size: usize,
) -> usize {
    if cctx.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    #[cfg(test)]
    {
        unsafe { compress_frame(dst, dst_capacity, src, src_size, 3) }
    }

    #[cfg(not(test))]
    {
        let level = unsafe { ZSTD_rust_simpleCompress2Level(cctx.cast_const(), src_size) };
        if level != c_int::MIN {
            let reset = unsafe { ZSTD_rust_resetCCtxForSimpleCompressionSession(cctx) };
            if ERR_isError(reset) {
                return reset;
            }
            let prepare =
                unsafe { ZSTD_rust_prepareCCtxForSimpleCompression(cctx, src_size, level) };
            if ERR_isError(prepare) {
                return prepare;
            }
            let result = unsafe { compress_frame(dst, dst_capacity, src, src_size, level) };
            if !ERR_isError(result) {
                unsafe { ZSTD_rust_markSimpleCompression2Complete(cctx) };
            }
            return result;
        }
        unsafe { ZSTD_compress2_c(cctx, dst, dst_capacity, src, src_size) }
    }
}

/// Compress a streaming call when the complete input and a full output bound
/// are already available for the ordinary context configuration.
///
/// The C implementation remains the fallback for partial-output streaming,
/// `ZSTD_e_continue`/`ZSTD_e_flush`, dictionaries, and every advanced context
/// configuration.  The Rust path resets the C-owned session after emitting a
/// complete frame so the same context can immediately start another frame.
#[cfg(not(test))]
#[no_mangle]
pub unsafe extern "C" fn ZSTD_compressStream2(
    cctx: *mut c_void,
    output: *mut ZSTD_outBuffer,
    input: *mut ZSTD_inBuffer,
    end_op: c_int,
) -> usize {
    if cctx.is_null() || output.is_null() || input.is_null() {
        return ERROR(ZstdErrorCode::Generic);
    }

    let output_ref = unsafe { &mut *output };
    let input_ref = unsafe { &mut *input };
    if output_ref.pos > output_ref.size {
        return ERROR(ZstdErrorCode::DstSizeTooSmall);
    }
    if input_ref.pos > input_ref.size {
        return ERROR(ZstdErrorCode::SrcSizeWrong);
    }

    let src_size = input_ref.size - input_ref.pos;
    if end_op == ZSTD_E_END {
        let level = unsafe { ZSTD_rust_simpleCompressStream2Level(cctx.cast_const(), src_size) };
        if level != c_int::MIN {
            let dst_capacity = output_ref.size - output_ref.pos;
            let bound = ZSTD_compressBound(src_size);
            if !ERR_isError(bound) && dst_capacity >= bound {
                if dst_capacity != 0 && output_ref.dst.is_null() {
                    return ERROR(ZstdErrorCode::DstBufferNull);
                }
                if src_size != 0 && input_ref.src.is_null() {
                    return ERROR(ZstdErrorCode::SrcSizeWrong);
                }
                let dst = if output_ref.dst.is_null() {
                    ptr::null_mut()
                } else {
                    unsafe { output_ref.dst.cast::<u8>().add(output_ref.pos).cast() }
                };
                let src = if input_ref.src.is_null() {
                    ptr::null()
                } else {
                    unsafe { input_ref.src.cast::<u8>().add(input_ref.pos).cast() }
                };
                let result = unsafe { compress_frame(dst, dst_capacity, src, src_size, level) };
                if !ERR_isError(result) {
                    output_ref.pos += result;
                    input_ref.pos = input_ref.size;
                    return unsafe { ZSTD_rust_resetCCtxForSimpleCompressionSession(cctx) };
                }
            }
        }
    }

    unsafe { ZSTD_compressStream2_c(cctx, output, input, end_op) }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::errors::ERR_getErrorCode;
    use crate::zstd_compress_params_api::{
        ZSTD_CCtxParams_getParameter, ZSTD_CCtxParams_setParameter,
    };
    use std::io::Write;
    use std::process::{Command, Stdio};

    const ZSTD_GREEDY: c_int = 3;
    const ZSTD_LAZY: c_int = 4;
    const ZSTD_BTULTRA: c_int = 8;
    const ZSTD_BTOPT: c_int = 7;
    const ZSTD_BTULTRA2: c_int = 9;

    struct EstimateCCtxSizeTestContext {
        compression_levels: Vec<c_int>,
        source_size_hints: Vec<u64>,
        parameter_tiers: Vec<u32>,
    }

    unsafe extern "C" fn estimate_cctx_size_test_get_c_params(
        context: *mut c_void,
        compression_level: c_int,
        source_size_hint: u64,
    ) -> ZSTD_compressionParameters {
        let context = unsafe { &mut *(context.cast::<EstimateCCtxSizeTestContext>()) };
        context.compression_levels.push(compression_level);
        context.source_size_hints.push(source_size_hint);
        ZSTD_compressionParameters {
            windowLog: context.source_size_hints.len() as u32,
            ..ZSTD_compressionParameters::default()
        }
    }

    unsafe extern "C" fn estimate_cctx_size_test_estimate(
        context: *mut c_void,
        c_params: ZSTD_compressionParameters,
    ) -> usize {
        let context = unsafe { &mut *(context.cast::<EstimateCCtxSizeTestContext>()) };
        context.parameter_tiers.push(c_params.windowLog);
        match c_params.windowLog {
            1 => 17,
            2 => 91,
            3 => 23,
            4 => 67,
            _ => ERROR(ZstdErrorCode::Generic),
        }
    }

    struct GenerateSequencesTestContext {
        events: Vec<&'static str>,
        target_c_block_size: c_int,
        nb_workers: c_int,
        allocation_fails: bool,
        collector_result: usize,
        compress_result: usize,
        sequence_count: usize,
    }

    unsafe extern "C" fn generate_sequences_get_parameter_test(
        context: *mut c_void,
        parameter: c_int,
        value: *mut c_int,
    ) -> usize {
        let context = unsafe { &mut *context.cast::<GenerateSequencesTestContext>() };
        let (event, result) = match parameter {
            ZSTD_C_TARGET_C_BLOCK_SIZE => ("target", context.target_c_block_size),
            ZSTD_C_NB_WORKERS => ("workers", context.nb_workers),
            _ => ("other", 0),
        };
        context.events.push(event);
        unsafe { *value = result };
        0
    }

    unsafe extern "C" fn generate_sequences_allocate_test(
        context: *mut c_void,
        _size: usize,
    ) -> *mut c_void {
        let context = unsafe { &mut *context.cast::<GenerateSequencesTestContext>() };
        context.events.push("allocate");
        if context.allocation_fails {
            ptr::null_mut()
        } else {
            Box::into_raw(Box::new(0_u8)).cast()
        }
    }

    unsafe extern "C" fn generate_sequences_free_test(context: *mut c_void, pointer: *mut c_void) {
        let context = unsafe { &mut *context.cast::<GenerateSequencesTestContext>() };
        context.events.push("free");
        if !pointer.is_null() {
            unsafe { drop(Box::from_raw(pointer.cast::<u8>())) };
        }
    }

    unsafe extern "C" fn generate_sequences_set_collector_test(
        context: *mut c_void,
        _out_seqs: *mut ZSTD_Sequence,
        _out_seqs_size: usize,
    ) -> usize {
        let context = unsafe { &mut *context.cast::<GenerateSequencesTestContext>() };
        context.events.push("collector");
        context.collector_result
    }

    unsafe extern "C" fn generate_sequences_compress2_test(
        context: *mut c_void,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
    ) -> usize {
        let context = unsafe { &mut *context.cast::<GenerateSequencesTestContext>() };
        context.events.push("compress2");
        context.compress_result
    }

    unsafe extern "C" fn generate_sequences_get_count_test(context: *mut c_void) -> usize {
        let context = unsafe { &mut *context.cast::<GenerateSequencesTestContext>() };
        context.events.push("count");
        context.sequence_count
    }

    fn generate_sequences_test_state(
        context: &mut GenerateSequencesTestContext,
    ) -> ZSTD_rust_generateSequencesState {
        ZSTD_rust_generateSequencesState {
            callback_context: context as *mut GenerateSequencesTestContext as *mut c_void,
            get_parameter: generate_sequences_get_parameter_test,
            allocate: generate_sequences_allocate_test,
            free: generate_sequences_free_test,
            set_collector: generate_sequences_set_collector_test,
            compress2: generate_sequences_compress2_test,
            get_count: generate_sequences_get_count_test,
        }
    }

    #[test]
    fn generate_sequences_rejects_unsupported_parameters_before_allocation() {
        let mut context = GenerateSequencesTestContext {
            events: Vec::new(),
            target_c_block_size: 1,
            nb_workers: 0,
            allocation_fails: false,
            collector_result: 0,
            compress_result: 0,
            sequence_count: 0,
        };
        let state = generate_sequences_test_state(&mut context);

        let result =
            unsafe { ZSTD_rust_generateSequences(&state, ptr::null_mut(), 0, ptr::null(), 0) };

        assert_eq!(
            ERR_getErrorCode(result),
            ZstdErrorCode::ParameterUnsupported as i32
        );
        assert_eq!(context.events, ["target"]);
    }

    #[test]
    fn generate_sequences_frees_temporary_output_on_setup_failure() {
        let mut context = GenerateSequencesTestContext {
            events: Vec::new(),
            target_c_block_size: 0,
            nb_workers: 0,
            allocation_fails: false,
            collector_result: ERROR(ZstdErrorCode::Generic),
            compress_result: 0,
            sequence_count: 0,
        };
        let state = generate_sequences_test_state(&mut context);

        let result =
            unsafe { ZSTD_rust_generateSequences(&state, ptr::null_mut(), 0, ptr::null(), 0) };

        assert_eq!(ERR_getErrorCode(result), ZstdErrorCode::Generic as i32);
        assert_eq!(
            context.events,
            ["target", "workers", "allocate", "collector", "free"]
        );
    }

    #[test]
    fn generate_sequences_runs_callbacks_in_order_and_returns_count() {
        let mut context = GenerateSequencesTestContext {
            events: Vec::new(),
            target_c_block_size: 0,
            nb_workers: 0,
            allocation_fails: false,
            collector_result: 0,
            compress_result: 0,
            sequence_count: 2,
        };
        let state = generate_sequences_test_state(&mut context);

        let result =
            unsafe { ZSTD_rust_generateSequences(&state, ptr::null_mut(), 0, ptr::null(), 0) };

        assert_eq!(result, 2);
        assert_eq!(
            context.events,
            [
                "target",
                "workers",
                "allocate",
                "collector",
                "compress2",
                "free",
                "count"
            ]
        );
    }

    unsafe extern "C" fn select_block_compressor_test_default(
        _match_state: *mut c_void,
        _seq_store: *mut SeqStore_t,
        _rep: *mut u32,
        _src: *const c_void,
        _src_size: usize,
    ) -> usize {
        7
    }

    unsafe extern "C" fn select_block_compressor_test_ordinary(
        _match_state: *mut c_void,
        _seq_store: *mut SeqStore_t,
        _rep: *mut u32,
        _src: *const c_void,
        _src_size: usize,
    ) -> usize {
        41
    }

    unsafe extern "C" fn select_block_compressor_test_row(
        _match_state: *mut c_void,
        _seq_store: *mut SeqStore_t,
        _rep: *mut u32,
        _src: *const c_void,
        _src_size: usize,
    ) -> usize {
        43
    }

    fn select_block_compressor_test_state(
        block_compressors: &[Option<BlockCompressorFn>],
        row_block_compressors: &[Option<BlockCompressorFn>],
        selected_compressor: &mut Option<BlockCompressorFn>,
    ) -> ZSTD_rust_selectBlockCompressorState {
        ZSTD_rust_selectBlockCompressorState {
            block_compressors: block_compressors.as_ptr(),
            row_block_compressors: row_block_compressors.as_ptr(),
            selected_compressor,
        }
    }

    #[test]
    fn select_block_compressor_dispatches_ordinary_and_row_tables() {
        let default = Some(select_block_compressor_test_default as BlockCompressorFn);
        let mut block_compressors = [default; 4 * ZSTD_RUST_BLOCK_COMPRESSOR_TABLE_WIDTH];
        let mut row_block_compressors = [default; 4 * ZSTD_RUST_ROW_BLOCK_COMPRESSOR_TABLE_WIDTH];
        block_compressors[ZSTD_RUST_BLOCK_COMPRESSOR_TABLE_WIDTH + 2] =
            Some(select_block_compressor_test_ordinary as BlockCompressorFn);
        row_block_compressors[3 * ZSTD_RUST_ROW_BLOCK_COMPRESSOR_TABLE_WIDTH] =
            Some(select_block_compressor_test_row as BlockCompressorFn);
        let mut selected_compressor = None;
        let state = select_block_compressor_test_state(
            &block_compressors,
            &row_block_compressors,
            &mut selected_compressor,
        );

        assert_eq!(
            unsafe { ZSTD_rust_selectBlockCompressor(&state, ZSTD_DFAST, ZSTD_RUST_PS_DISABLE, 1) },
            0
        );
        let ordinary = selected_compressor.expect("ordinary compressor should be selected");
        assert_eq!(
            unsafe {
                ordinary(
                    ptr::null_mut(),
                    ptr::null_mut(),
                    ptr::null_mut(),
                    ptr::null(),
                    0,
                )
            },
            41
        );

        assert_eq!(
            unsafe { ZSTD_rust_selectBlockCompressor(&state, ZSTD_GREEDY, ZSTD_RUST_PS_ENABLE, 3) },
            0
        );
        let row = selected_compressor.expect("row compressor should be selected");
        assert_eq!(
            unsafe {
                row(
                    ptr::null_mut(),
                    ptr::null_mut(),
                    ptr::null_mut(),
                    ptr::null(),
                    0,
                )
            },
            43
        );
    }

    #[test]
    fn select_block_compressor_rejects_an_excluded_dispatch_leaf() {
        let default = Some(select_block_compressor_test_default as BlockCompressorFn);
        let mut block_compressors = [default; 4 * ZSTD_RUST_BLOCK_COMPRESSOR_TABLE_WIDTH];
        let row_block_compressors = [default; 4 * ZSTD_RUST_ROW_BLOCK_COMPRESSOR_TABLE_WIDTH];
        block_compressors[1] = None;
        let mut selected_compressor = None;
        let state = select_block_compressor_test_state(
            &block_compressors,
            &row_block_compressors,
            &mut selected_compressor,
        );

        let result =
            unsafe { ZSTD_rust_selectBlockCompressor(&state, ZSTD_FAST, ZSTD_RUST_PS_DISABLE, 0) };

        assert!(ERR_isError(result));
        assert!(selected_compressor.is_none());
    }

    #[derive(Default)]
    struct BuildSeqStoreSelectProbe {
        events: Vec<&'static str>,
        external_result: usize,
        ldm_result: usize,
        producer_result: usize,
        producer_complete: c_int,
        producer_allow_fallback: c_int,
        internal_result: usize,
    }

    unsafe fn build_seq_store_select_probe(
        context: *mut c_void,
    ) -> &'static mut BuildSeqStoreSelectProbe {
        unsafe { &mut *context.cast::<BuildSeqStoreSelectProbe>() }
    }

    unsafe extern "C" fn build_seq_store_test_skip(_context: *mut c_void, _src_size: usize) {}

    unsafe extern "C" fn build_seq_store_test_prepare(
        _context: *mut c_void,
        _src: *const c_void,
        _src_size: usize,
    ) {
    }

    unsafe extern "C" fn build_seq_store_test_external(
        context: *mut c_void,
        _seq_store: *mut SeqStore_t,
        _next_rep: *mut u32,
        _src: *const c_void,
        _src_size: usize,
    ) -> usize {
        let probe = unsafe { build_seq_store_select_probe(context) };
        probe.events.push("external");
        probe.external_result
    }

    unsafe extern "C" fn build_seq_store_test_ldm(
        context: *mut c_void,
        _seq_store: *mut SeqStore_t,
        _next_rep: *mut u32,
        _src: *const c_void,
        _src_size: usize,
    ) -> usize {
        let probe = unsafe { build_seq_store_select_probe(context) };
        probe.events.push("ldm");
        probe.ldm_result
    }

    unsafe extern "C" fn build_seq_store_test_producer(
        context: *mut c_void,
        _src: *const c_void,
        _src_size: usize,
        seq_store_complete: *mut c_int,
        allow_fallback: *mut c_int,
    ) -> usize {
        let probe = unsafe { build_seq_store_select_probe(context) };
        probe.events.push("producer");
        unsafe {
            *seq_store_complete = probe.producer_complete;
            *allow_fallback = probe.producer_allow_fallback;
        }
        probe.producer_result
    }

    unsafe extern "C" fn build_seq_store_test_internal(
        context: *mut c_void,
        _seq_store: *mut SeqStore_t,
        _next_rep: *mut u32,
        _src: *const c_void,
        _src_size: usize,
    ) -> usize {
        let probe = unsafe { build_seq_store_select_probe(context) };
        probe.events.push("internal");
        probe.internal_result
    }

    unsafe extern "C" fn build_seq_store_test_clear(context: *mut c_void) {
        let probe = unsafe { build_seq_store_select_probe(context) };
        probe.events.push("clear");
    }

    fn build_seq_store_select_test_state(
        probe: &mut BuildSeqStoreSelectProbe,
        has_external_sequences: c_int,
        ldm_enabled: c_int,
        has_external_sequence_producer: c_int,
        enable_match_finder_fallback: c_int,
    ) -> ZSTD_rust_buildSeqStoreState {
        ZSTD_rust_buildSeqStoreState {
            seq_store: ptr::null_mut(),
            prev_c_block: ptr::null_mut(),
            next_c_block: ptr::null_mut(),
            callback_context: (probe as *mut BuildSeqStoreSelectProbe).cast(),
            min_match: 3,
            validate_seq_store: 0,
            skip_small_block: build_seq_store_test_skip,
            prepare_match_state: build_seq_store_test_prepare,
            has_external_sequences,
            ldm_enabled,
            has_external_sequence_producer,
            enable_match_finder_fallback,
            compress_external_sequences: build_seq_store_test_external,
            compress_ldm: build_seq_store_test_ldm,
            try_external_sequence_producer: build_seq_store_test_producer,
            compress_internal: build_seq_store_test_internal,
            clear_ldm_seq_store: build_seq_store_test_clear,
        }
    }

    fn run_build_seq_store_select_test(state: &ZSTD_rust_buildSeqStoreState) -> (usize, c_int) {
        let mut seq_store = unsafe { MaybeUninit::<SeqStore_t>::zeroed().assume_init() };
        let mut next_rep = [0u32; ZSTD_REP_NUM];
        let source = [0u8; 1];
        let mut seq_store_complete = 99;
        let result = unsafe {
            build_seq_store_select_sequences_body_with(
                state,
                &mut seq_store,
                next_rep.as_mut_ptr(),
                source.as_ptr().cast(),
                source.len(),
                &mut seq_store_complete,
            )
        };
        (result, seq_store_complete)
    }

    #[test]
    fn build_seq_store_selects_preloaded_external_sequences_first() {
        let mut probe = BuildSeqStoreSelectProbe {
            external_result: 11,
            ldm_result: 12,
            internal_result: 13,
            ..Default::default()
        };
        let state = build_seq_store_select_test_state(&mut probe, 1, 1, 0, 0);

        let (result, seq_store_complete) = run_build_seq_store_select_test(&state);

        assert_eq!(result, probe.external_result);
        assert_eq!(seq_store_complete, 0);
        assert_eq!(probe.events, ["external"]);
    }

    #[test]
    fn build_seq_store_uses_ldm_when_no_external_sequences_are_pending() {
        let mut probe = BuildSeqStoreSelectProbe {
            ldm_result: 19,
            internal_result: 23,
            ..Default::default()
        };
        let state = build_seq_store_select_test_state(&mut probe, 0, 1, 0, 0);

        let (result, seq_store_complete) = run_build_seq_store_select_test(&state);

        assert_eq!(result, probe.ldm_result);
        assert_eq!(seq_store_complete, 0);
        assert_eq!(probe.events, ["ldm"]);
    }

    #[test]
    fn build_seq_store_rejects_external_producer_with_preloaded_sequences_or_ldm() {
        for (has_external_sequences, ldm_enabled) in [(1, 0), (0, 1)] {
            let mut probe = BuildSeqStoreSelectProbe::default();
            let state = build_seq_store_select_test_state(
                &mut probe,
                has_external_sequences,
                ldm_enabled,
                1,
                1,
            );

            let (result, seq_store_complete) = run_build_seq_store_select_test(&state);

            assert_eq!(
                result,
                ERROR(ZstdErrorCode::ParameterCombinationUnsupported)
            );
            assert_eq!(seq_store_complete, 0);
            assert!(probe.events.is_empty());
        }
    }

    #[test]
    fn build_seq_store_clears_ldm_after_external_producer_completion() {
        let mut probe = BuildSeqStoreSelectProbe {
            producer_complete: 1,
            producer_allow_fallback: 1,
            producer_result: 0,
            ..Default::default()
        };
        let state = build_seq_store_select_test_state(&mut probe, 0, 0, 1, 1);

        let (result, seq_store_complete) = run_build_seq_store_select_test(&state);

        assert_eq!(result, 0);
        assert_eq!(seq_store_complete, 1);
        assert_eq!(probe.events, ["producer", "clear"]);
    }

    #[test]
    fn build_seq_store_does_not_fallback_when_producer_disallows_it() {
        let producer_result = ERROR(ZstdErrorCode::SequenceProducerFailed);
        let mut probe = BuildSeqStoreSelectProbe {
            producer_result,
            producer_allow_fallback: 1,
            internal_result: 17,
            ..Default::default()
        };
        let state = build_seq_store_select_test_state(&mut probe, 0, 0, 1, 0);

        let (result, seq_store_complete) = run_build_seq_store_select_test(&state);

        assert_eq!(result, producer_result);
        assert_eq!(seq_store_complete, 0);
        assert_eq!(probe.events, ["producer"]);
    }

    #[test]
    fn build_seq_store_falls_back_after_external_producer_error() {
        let producer_result = ERROR(ZstdErrorCode::SequenceProducerFailed);
        let mut probe = BuildSeqStoreSelectProbe {
            producer_result,
            producer_allow_fallback: 1,
            internal_result: 23,
            ..Default::default()
        };
        let state = build_seq_store_select_test_state(&mut probe, 0, 0, 1, 1);

        let (result, seq_store_complete) = run_build_seq_store_select_test(&state);

        assert_eq!(result, probe.internal_result);
        assert_eq!(seq_store_complete, 0);
        assert_eq!(probe.events, ["producer", "clear", "internal"]);
    }

    #[test]
    fn build_seq_store_clears_ldm_before_internal_compression() {
        let mut probe = BuildSeqStoreSelectProbe {
            internal_result: 29,
            ..Default::default()
        };
        let state = build_seq_store_select_test_state(&mut probe, 0, 0, 0, 0);

        let (result, seq_store_complete) = run_build_seq_store_select_test(&state);

        assert_eq!(result, probe.internal_result);
        assert_eq!(seq_store_complete, 0);
        assert_eq!(probe.events, ["clear", "internal"]);
    }

    #[derive(Default)]
    struct ResetMatchStateTestContext {
        events: Vec<c_int>,
        reserves: Vec<(c_int, usize)>,
        pointers: Vec<(c_int, *mut c_void)>,
        zeroed: Vec<(usize, usize)>,
        storage: [usize; 32],
        fail_after: usize,
    }

    unsafe fn reset_match_state_test_context(
        context: *mut c_void,
    ) -> &'static mut ResetMatchStateTestContext {
        unsafe { &mut *context.cast::<ResetMatchStateTestContext>() }
    }

    unsafe extern "C" fn reset_match_state_test_callback(context: *mut c_void) {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(1);
    }

    unsafe extern "C" fn reset_match_state_test_mark_dirty(context: *mut c_void) {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(2);
    }

    unsafe extern "C" fn reset_match_state_test_invalidate(context: *mut c_void) {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(3);
    }

    unsafe extern "C" fn reset_match_state_test_clear(context: *mut c_void) {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(4);
    }

    unsafe extern "C" fn reset_match_state_test_clean(context: *mut c_void) {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(5);
    }

    unsafe extern "C" fn reset_match_state_test_advance(context: *mut c_void) {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(6);
    }

    unsafe extern "C" fn reset_match_state_test_reserve(
        context: *mut c_void,
        reserve_kind: c_int,
        size: usize,
    ) -> *mut c_void {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(100 + reserve_kind);
        let index = context.reserves.len();
        context.reserves.push((reserve_kind, size));
        if context.fail_after != 0 && index + 1 >= context.fail_after {
            ptr::null_mut()
        } else {
            unsafe { context.storage.as_mut_ptr().add(index).cast() }
        }
    }

    unsafe extern "C" fn reset_match_state_test_reserve_failed(context: *mut c_void) -> c_int {
        let context = unsafe { reset_match_state_test_context(context) };
        c_int::from(context.fail_after != 0 && context.reserves.len() >= context.fail_after)
    }

    unsafe extern "C" fn reset_match_state_test_set_pointer(
        context: *mut c_void,
        pointer_kind: c_int,
        pointer: *mut c_void,
    ) {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(200 + pointer_kind);
        context.pointers.push((pointer_kind, pointer));
    }

    unsafe extern "C" fn reset_match_state_test_zero(
        context: *mut c_void,
        pointer: *mut c_void,
        size: usize,
    ) {
        let context = unsafe { reset_match_state_test_context(context) };
        context.events.push(7);
        context.zeroed.push((pointer as usize, size));
    }

    #[allow(clippy::too_many_arguments)]
    fn reset_match_state_test_state(
        context: &mut ResetMatchStateTestContext,
        c_params: ZSTD_compressionParameters,
        dedicated_dict_search: c_int,
        use_row_match_finder: c_int,
        comp_reset_policy: c_int,
        index_reset_policy: c_int,
        reset_target: c_int,
        hash_log3: &mut c_uint,
        row_hash_log: &mut c_uint,
        hash_salt: &mut u64,
        lazy_skipping: &mut c_int,
        c_params_out: &mut ZSTD_compressionParameters,
    ) -> ZSTD_rust_resetMatchStateState {
        ZSTD_rust_resetMatchStateState {
            callback_context: (context as *mut ResetMatchStateTestContext).cast(),
            c_params,
            dedicated_dict_search,
            use_row_match_finder,
            comp_reset_policy,
            index_reset_policy,
            reset_target,
            hash_log3_max: 17,
            lit_freq_size: 256 * size_of::<c_uint>(),
            lit_length_freq_size: 36 * size_of::<c_uint>(),
            match_length_freq_size: 53 * size_of::<c_uint>(),
            off_code_freq_size: 32 * size_of::<c_uint>(),
            match_size: 4099 * 2 * size_of::<c_uint>(),
            optimal_size: 4099 * 8 * size_of::<c_uint>(),
            hash_log3,
            row_hash_log,
            hash_salt,
            lazy_skipping,
            c_params_out,
            set_pointer: Some(reset_match_state_test_set_pointer),
            window_init: Some(reset_match_state_test_callback),
            mark_tables_dirty: Some(reset_match_state_test_mark_dirty),
            invalidate_match_state: Some(reset_match_state_test_invalidate),
            clear_tables: Some(reset_match_state_test_clear),
            clean_tables: Some(reset_match_state_test_clean),
            advance_hash_salt: Some(reset_match_state_test_advance),
            reserve: Some(reset_match_state_test_reserve),
            reserve_failed: Some(reset_match_state_test_reserve_failed),
            zero: Some(reset_match_state_test_zero),
        }
    }

    fn reset_match_state_test_params(
        strategy: c_int,
        search_log: u32,
        min_match: u32,
    ) -> ZSTD_compressionParameters {
        ZSTD_compressionParameters {
            windowLog: 20,
            chainLog: 11,
            hashLog: 12,
            searchLog: search_log,
            minMatch: min_match,
            targetLength: 16,
            strategy,
        }
    }

    #[test]
    fn reset_match_state_orders_cctx_opt_allocations() {
        let c_params = reset_match_state_test_params(ZSTD_BTOPT, 5, 3);
        let mut context = ResetMatchStateTestContext::default();
        let mut hash_log3 = 99;
        let mut row_hash_log = 99;
        let mut hash_salt = 7;
        let mut lazy_skipping = 9;
        let mut c_params_out = ZSTD_compressionParameters::default();
        let state = reset_match_state_test_state(
            &mut context,
            c_params,
            0,
            ZSTD_RUST_PS_DISABLE,
            0,
            1,
            1,
            &mut hash_log3,
            &mut row_hash_log,
            &mut hash_salt,
            &mut lazy_skipping,
            &mut c_params_out,
        );

        let result = unsafe { ZSTD_rust_resetMatchState(&state) };

        assert_eq!(result, 0);
        assert_eq!(hash_log3, 17);
        assert_eq!(row_hash_log, 99);
        assert_eq!(hash_salt, 7);
        assert_eq!(lazy_skipping, 0);
        assert_eq!(c_params_out, c_params);
        assert_eq!(
            context.events,
            [
                1, 2, 3, 4, 100, 200, 100, 201, 100, 202, 5, 102, 204, 102, 205, 102, 206, 102,
                207, 102, 208, 102, 209,
            ]
        );
        assert_eq!(
            context.reserves,
            [
                (0, (1 << 12) * size_of::<c_uint>()),
                (0, (1 << 11) * size_of::<c_uint>()),
                (0, (1 << 17) * size_of::<c_uint>()),
                (2, 256 * size_of::<c_uint>()),
                (2, 36 * size_of::<c_uint>()),
                (2, 53 * size_of::<c_uint>()),
                (2, 32 * size_of::<c_uint>()),
                (2, 4099 * 2 * size_of::<c_uint>()),
                (2, 4099 * 8 * size_of::<c_uint>()),
            ]
        );
        assert_eq!(context.pointers.len(), 9);
        assert!(context.zeroed.is_empty());
    }

    #[test]
    fn reset_match_state_salts_cctx_row_tables_without_zeroing() {
        let c_params = reset_match_state_test_params(ZSTD_GREEDY, 6, 4);
        let mut context = ResetMatchStateTestContext::default();
        let mut hash_log3 = 99;
        let mut row_hash_log = 99;
        let mut hash_salt = 7;
        let mut lazy_skipping = 9;
        let mut c_params_out = ZSTD_compressionParameters::default();
        let state = reset_match_state_test_state(
            &mut context,
            c_params,
            0,
            ZSTD_RUST_PS_ENABLE,
            0,
            0,
            1,
            &mut hash_log3,
            &mut row_hash_log,
            &mut hash_salt,
            &mut lazy_skipping,
            &mut c_params_out,
        );

        let result = unsafe { ZSTD_rust_resetMatchState(&state) };

        assert_eq!(result, 0);
        assert_eq!(hash_log3, 0);
        assert_eq!(row_hash_log, 6);
        assert_eq!(hash_salt, 7);
        assert_eq!(c_params_out, c_params);
        assert_eq!(
            context.events,
            [3, 4, 100, 200, 100, 201, 100, 202, 5, 101, 203, 6]
        );
        assert_eq!(
            context.reserves,
            [
                (0, (1 << 12) * size_of::<c_uint>()),
                (0, 0),
                (0, 0),
                (1, 1 << 12),
            ]
        );
        assert_eq!(context.pointers.len(), 4);
        assert!(context.zeroed.is_empty());
    }

    #[test]
    fn reset_match_state_uses_cdict_row_policy_without_opt_storage() {
        let c_params = reset_match_state_test_params(ZSTD_GREEDY, 6, 4);
        let mut context = ResetMatchStateTestContext::default();
        let mut hash_log3 = 99;
        let mut row_hash_log = 99;
        let mut hash_salt = 7;
        let mut lazy_skipping = 9;
        let mut c_params_out = ZSTD_compressionParameters::default();
        let state = reset_match_state_test_state(
            &mut context,
            c_params,
            1,
            ZSTD_RUST_PS_ENABLE,
            1,
            0,
            0,
            &mut hash_log3,
            &mut row_hash_log,
            &mut hash_salt,
            &mut lazy_skipping,
            &mut c_params_out,
        );

        let result = unsafe { ZSTD_rust_resetMatchState(&state) };

        assert_eq!(result, 0);
        assert_eq!(hash_log3, 0);
        assert_eq!(row_hash_log, 6);
        assert_eq!(hash_salt, 0);
        assert_eq!(c_params_out, c_params);
        assert_eq!(
            context.events,
            [3, 4, 100, 200, 100, 201, 100, 202, 102, 203, 7]
        );
        assert_eq!(
            context.reserves,
            [
                (0, (1 << 12) * size_of::<c_uint>()),
                (0, (1 << 11) * size_of::<c_uint>()),
                (0, 0),
                (2, 1 << 12),
            ]
        );
        assert_eq!(context.pointers.len(), 4);
        assert_eq!(context.zeroed.len(), 1);
        assert_eq!(context.zeroed[0].1, 1 << 12);
    }

    #[test]
    fn reset_match_state_propagates_table_allocation_failure() {
        let c_params = reset_match_state_test_params(ZSTD_GREEDY, 4, 4);
        let mut context = ResetMatchStateTestContext {
            fail_after: 1,
            ..ResetMatchStateTestContext::default()
        };
        let mut hash_log3 = 99;
        let mut row_hash_log = 99;
        let mut hash_salt = 7;
        let mut lazy_skipping = 9;
        let mut c_params_out = ZSTD_compressionParameters::default();
        let state = reset_match_state_test_state(
            &mut context,
            c_params,
            0,
            ZSTD_RUST_PS_DISABLE,
            0,
            1,
            1,
            &mut hash_log3,
            &mut row_hash_log,
            &mut hash_salt,
            &mut lazy_skipping,
            &mut c_params_out,
        );

        let result = unsafe { ZSTD_rust_resetMatchState(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, [1, 2, 3, 4, 100, 200, 100, 201, 100, 202]);
        assert_eq!(context.pointers.len(), 3);
        assert_eq!(hash_log3, 0);
        assert_eq!(lazy_skipping, 0);
        assert_eq!(c_params_out, ZSTD_compressionParameters::default());
    }

    #[test]
    fn reference_external_sequences_resets_store_state() {
        let mut source = [0u8; 3];
        let sequence = source.as_mut_ptr().cast::<c_void>();
        let mut stored_sequence = ptr::null_mut();
        let mut pos = 7;
        let mut pos_in_sequence = 8;
        let mut size = 9;
        let mut capacity = 10;
        let state = ZSTD_rust_externalSequenceStoreState {
            seq: &mut stored_sequence,
            pos: &mut pos,
            pos_in_sequence: &mut pos_in_sequence,
            size: &mut size,
            capacity: &mut capacity,
        };

        unsafe { ZSTD_rust_referenceExternalSequences(&state, sequence, 11) };

        assert_eq!(stored_sequence, sequence);
        assert_eq!(pos, 0);
        assert_eq!(pos_in_sequence, 0);
        assert_eq!(size, 11);
        assert_eq!(capacity, 11);
    }

    #[test]
    fn reference_external_sequences_rejects_incomplete_state() {
        let mut pos = 7;
        let mut pos_in_sequence = 8;
        let mut size = 9;
        let mut capacity = 10;
        let state = ZSTD_rust_externalSequenceStoreState {
            seq: ptr::null_mut(),
            pos: &mut pos,
            pos_in_sequence: &mut pos_in_sequence,
            size: &mut size,
            capacity: &mut capacity,
        };

        unsafe { ZSTD_rust_referenceExternalSequences(&state, ptr::null_mut(), 11) };

        assert_eq!(pos, 7);
        assert_eq!(pos_in_sequence, 8);
        assert_eq!(size, 9);
        assert_eq!(capacity, 10);
    }

    #[derive(Default)]
    struct ExternalSequenceProducerProbe {
        events: Vec<&'static str>,
        sequences: Vec<ZSTD_Sequence>,
        producer_result: usize,
        producer_dict: *const c_void,
        producer_dict_size: usize,
        producer_level: c_int,
        producer_window_size: usize,
        transfer_sequence_count: usize,
        transfer_src_size: usize,
        transfer_result: usize,
    }

    unsafe fn external_sequence_producer_probe(
        context: *mut c_void,
    ) -> &'static mut ExternalSequenceProducerProbe {
        unsafe { &mut *context.cast::<ExternalSequenceProducerProbe>() }
    }

    unsafe extern "C" fn external_sequence_producer_test_producer(
        context: *mut c_void,
        out_seqs: *mut ZSTD_Sequence,
        out_seqs_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        dict: *const c_void,
        dict_size: usize,
        compression_level: c_int,
        window_size: usize,
    ) -> usize {
        let probe = unsafe { external_sequence_producer_probe(context) };
        probe.events.push("produce");
        probe.producer_dict = dict;
        probe.producer_dict_size = dict_size;
        probe.producer_level = compression_level;
        probe.producer_window_size = window_size;
        assert!(probe.sequences.len() <= out_seqs_capacity);
        unsafe {
            ptr::copy_nonoverlapping(probe.sequences.as_ptr(), out_seqs, probe.sequences.len());
        }
        probe.producer_result
    }

    unsafe extern "C" fn external_sequence_producer_test_transfer(
        context: *mut c_void,
        _seq_pos: *mut ZSTD_SequencePosition,
        _in_seqs: *const ZSTD_Sequence,
        in_seqs_size: usize,
        _src: *const c_void,
        block_size: usize,
    ) -> usize {
        let probe = unsafe { external_sequence_producer_probe(context) };
        probe.events.push("transfer");
        probe.transfer_sequence_count = in_seqs_size;
        probe.transfer_src_size = block_size;
        probe.transfer_result
    }

    fn external_sequence_producer_test_state(
        probe: &mut ExternalSequenceProducerProbe,
        ext_seq_buf: &mut [ZSTD_Sequence],
        ext_seq_buf_capacity: &usize,
        src: &[u8],
        src_size: &usize,
        compression_level: &c_int,
        window_size: &usize,
        external_seq_count: &mut usize,
        seq_store_complete: &mut c_int,
        allow_fallback: &mut c_int,
    ) -> ZSTD_rust_externalSequenceProducerState {
        let callback_context = (probe as *mut ExternalSequenceProducerProbe).cast();
        ZSTD_rust_externalSequenceProducerState {
            callback_context,
            producer_state: callback_context,
            producer: Some(external_sequence_producer_test_producer),
            ext_seq_buf: ext_seq_buf.as_mut_ptr(),
            ext_seq_buf_capacity,
            src: src.as_ptr().cast(),
            src_size,
            compression_level,
            window_size,
            transfer: Some(external_sequence_producer_test_transfer),
            external_seq_count,
            seq_store_complete,
            allow_fallback,
        }
    }

    #[test]
    fn external_sequence_producer_success_transfers_after_post_processing() {
        let source = [1u8, 2, 3, 4, 5];
        let mut probe = ExternalSequenceProducerProbe {
            sequences: vec![ZSTD_Sequence {
                offset: 0,
                litLength: source.len() as u32,
                matchLength: 0,
                rep: 0,
            }],
            producer_result: 1,
            ..Default::default()
        };
        let mut ext_seq_buf = [ZSTD_Sequence {
            offset: 0,
            litLength: 0,
            matchLength: 0,
            rep: 0,
        }; 2];
        let ext_seq_buf_capacity = ext_seq_buf.len();
        let src_size = source.len();
        let compression_level = 7;
        let window_size = 1 << 20;
        let mut external_seq_count = 0;
        let mut seq_store_complete = 0;
        let mut allow_fallback = 0;
        let state = external_sequence_producer_test_state(
            &mut probe,
            &mut ext_seq_buf,
            &ext_seq_buf_capacity,
            &source,
            &src_size,
            &compression_level,
            &window_size,
            &mut external_seq_count,
            &mut seq_store_complete,
            &mut allow_fallback,
        );

        let result = unsafe { ZSTD_rust_tryExternalSequenceProducer(&state) };

        assert_eq!(result, 0);
        assert_eq!(probe.events, ["produce", "transfer"]);
        assert!(probe.producer_dict.is_null());
        assert_eq!(probe.producer_dict_size, 0);
        assert_eq!(probe.producer_level, compression_level);
        assert_eq!(probe.producer_window_size, window_size);
        assert_eq!(probe.transfer_sequence_count, 1);
        assert_eq!(probe.transfer_src_size, source.len());
        assert_eq!(external_seq_count, 1);
        assert_eq!(seq_store_complete, 1);
        assert_eq!(allow_fallback, 0);
    }

    #[test]
    fn external_sequence_producer_errors_enable_fallback_before_transfer() {
        let source = [1u8, 2, 3];
        let mut probe = ExternalSequenceProducerProbe {
            producer_result: ERROR(ZstdErrorCode::SequenceProducerFailed),
            ..Default::default()
        };
        let mut ext_seq_buf = [ZSTD_Sequence {
            offset: 0,
            litLength: 0,
            matchLength: 0,
            rep: 0,
        }; 2];
        let ext_seq_buf_capacity = ext_seq_buf.len();
        let src_size = source.len();
        let compression_level = 3;
        let window_size = 1 << 20;
        let mut external_seq_count = 0;
        let mut seq_store_complete = 0;
        let mut allow_fallback = 0;
        let state = external_sequence_producer_test_state(
            &mut probe,
            &mut ext_seq_buf,
            &ext_seq_buf_capacity,
            &source,
            &src_size,
            &compression_level,
            &window_size,
            &mut external_seq_count,
            &mut seq_store_complete,
            &mut allow_fallback,
        );

        let result = unsafe { ZSTD_rust_tryExternalSequenceProducer(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::SequenceProducerFailed));
        assert_eq!(probe.events, ["produce"]);
        assert_eq!(external_seq_count, result);
        assert_eq!(seq_store_complete, 0);
        assert_eq!(allow_fallback, 1);
    }

    #[test]
    fn external_sequence_producer_invalid_length_does_not_enable_fallback() {
        let source = [1u8, 2, 3];
        let mut probe = ExternalSequenceProducerProbe {
            sequences: vec![ZSTD_Sequence {
                offset: 0,
                litLength: (source.len() + 1) as u32,
                matchLength: 0,
                rep: 0,
            }],
            producer_result: 1,
            ..Default::default()
        };
        let mut ext_seq_buf = [ZSTD_Sequence {
            offset: 0,
            litLength: 0,
            matchLength: 0,
            rep: 0,
        }; 2];
        let ext_seq_buf_capacity = ext_seq_buf.len();
        let src_size = source.len();
        let compression_level = 3;
        let window_size = 1 << 20;
        let mut external_seq_count = 0;
        let mut seq_store_complete = 0;
        let mut allow_fallback = 0;
        let state = external_sequence_producer_test_state(
            &mut probe,
            &mut ext_seq_buf,
            &ext_seq_buf_capacity,
            &source,
            &src_size,
            &compression_level,
            &window_size,
            &mut external_seq_count,
            &mut seq_store_complete,
            &mut allow_fallback,
        );

        let result = unsafe { ZSTD_rust_tryExternalSequenceProducer(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::ExternalSequencesInvalid));
        assert_eq!(probe.events, ["produce"]);
        assert_eq!(seq_store_complete, 0);
        assert_eq!(allow_fallback, 0);
    }

    #[test]
    fn external_sequence_producer_transfer_errors_do_not_enable_fallback() {
        let source = [1u8, 2, 3];
        let mut probe = ExternalSequenceProducerProbe {
            sequences: vec![ZSTD_Sequence {
                offset: 0,
                litLength: source.len() as u32,
                matchLength: 0,
                rep: 0,
            }],
            producer_result: 1,
            transfer_result: ERROR(ZstdErrorCode::ExternalSequencesInvalid),
            ..Default::default()
        };
        let mut ext_seq_buf = [ZSTD_Sequence {
            offset: 0,
            litLength: 0,
            matchLength: 0,
            rep: 0,
        }; 2];
        let ext_seq_buf_capacity = ext_seq_buf.len();
        let src_size = source.len();
        let compression_level = 3;
        let window_size = 1 << 20;
        let mut external_seq_count = 0;
        let mut seq_store_complete = 0;
        let mut allow_fallback = 0;
        let state = external_sequence_producer_test_state(
            &mut probe,
            &mut ext_seq_buf,
            &ext_seq_buf_capacity,
            &source,
            &src_size,
            &compression_level,
            &window_size,
            &mut external_seq_count,
            &mut seq_store_complete,
            &mut allow_fallback,
        );

        let result = unsafe { ZSTD_rust_tryExternalSequenceProducer(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::ExternalSequencesInvalid));
        assert_eq!(probe.events, ["produce", "transfer"]);
        assert_eq!(seq_store_complete, 0);
        assert_eq!(allow_fallback, 0);
    }

    #[derive(Default)]
    struct Compress2TestContext {
        events: Vec<&'static str>,
        in_buffer_mode: c_int,
        out_buffer_mode: c_int,
        reset_result: usize,
        stream_result: usize,
        output_pos: usize,
        input_pos: usize,
    }

    unsafe fn compress2_test_context(context: *mut c_void) -> &'static mut Compress2TestContext {
        unsafe { &mut *context.cast::<Compress2TestContext>() }
    }

    unsafe extern "C" fn compress2_test_reset(context: *mut c_void) -> usize {
        let context = unsafe { compress2_test_context(context) };
        context.events.push("reset");
        context.reset_result
    }

    unsafe extern "C" fn compress2_test_set_buffer_modes(
        context: *mut c_void,
        in_buffer_mode: c_int,
        out_buffer_mode: c_int,
    ) {
        let context = unsafe { compress2_test_context(context) };
        context.events.push(
            if in_buffer_mode == ZSTD_BM_STABLE && out_buffer_mode == ZSTD_BM_STABLE {
                "stable"
            } else {
                "restore"
            },
        );
        context.in_buffer_mode = in_buffer_mode;
        context.out_buffer_mode = out_buffer_mode;
    }

    unsafe extern "C" fn compress2_test_stream_end(
        context: *mut c_void,
        _dst: *mut c_void,
        _dst_capacity: usize,
        dst_pos: *mut usize,
        _src: *const c_void,
        _src_size: usize,
        src_pos: *mut usize,
    ) -> usize {
        let context = unsafe { compress2_test_context(context) };
        context.events.push("stream-end");
        unsafe {
            *dst_pos = context.output_pos;
            *src_pos = context.input_pos;
        }
        context.stream_result
    }

    fn compress2_test_state(
        context: &mut Compress2TestContext,
        original_in_buffer_mode: c_int,
        original_out_buffer_mode: c_int,
    ) -> ZSTD_rust_compress2State {
        ZSTD_rust_compress2State {
            callback_context: (context as *mut Compress2TestContext).cast(),
            reset_session: compress2_test_reset,
            set_buffer_modes: compress2_test_set_buffer_modes,
            compress_stream_end: compress2_test_stream_end,
            original_in_buffer_mode,
            original_out_buffer_mode,
        }
    }

    #[test]
    fn compress2_fallback_restores_modes_after_codec_error() {
        let mut context = Compress2TestContext {
            stream_result: ERROR(ZstdErrorCode::MemoryAllocation),
            output_pos: 4,
            input_pos: 3,
            in_buffer_mode: 7,
            out_buffer_mode: 8,
            ..Compress2TestContext::default()
        };
        let state = compress2_test_state(&mut context, 7, 8);
        let src = [0u8; 3];
        let mut dst = [0u8; 4];

        let result = unsafe {
            ZSTD_rust_compress2(
                &state,
                dst.as_mut_ptr().cast(),
                dst.len(),
                src.as_ptr().cast(),
                src.len(),
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset", "stable", "stream-end", "restore"]);
        assert_eq!((context.in_buffer_mode, context.out_buffer_mode), (7, 8));
    }

    #[test]
    fn compress2_fallback_maps_remaining_output_to_dst_size_too_small() {
        let mut context = Compress2TestContext {
            stream_result: 1,
            output_pos: 4,
            input_pos: 3,
            in_buffer_mode: 7,
            out_buffer_mode: 8,
            ..Compress2TestContext::default()
        };
        let state = compress2_test_state(&mut context, 7, 8);
        let src = [0u8; 3];
        let mut dst = [0u8; 4];

        let result = unsafe {
            ZSTD_rust_compress2(
                &state,
                dst.as_mut_ptr().cast(),
                dst.len(),
                src.as_ptr().cast(),
                src.len(),
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::DstSizeTooSmall));
        assert_eq!(context.events, ["reset", "stable", "stream-end", "restore"]);
        assert_eq!((context.in_buffer_mode, context.out_buffer_mode), (7, 8));
    }

    #[derive(Default)]
    struct CompressEndTestContext {
        events: Vec<&'static str>,
        continue_result: usize,
        trace_extra: usize,
        continue_frame: c_uint,
        continue_last_frame_chunk: c_uint,
        stage: c_int,
        window: ZSTD_rust_windowUpdateState,
        force_non_contiguous: c_int,
        next_to_update: c_uint,
        window_projection: ZSTD_rust_compressContinueWindowProjection,
        frame_chunk_clamp_state: Option<ZSTD_rust_frameChunkClampState>,
        frame_chunk_prepare_state: Option<ZSTD_rust_frameChunkPrepareState>,
        frame_chunk_state: Option<ZSTD_rust_frameChunkState>,
        continue_state: Option<ZSTD_rust_compressContinueState>,
        is_first_block: c_int,
        produced_c_size: u64,
    }

    static COMPRESS_END_TEST_CHECKSUM_STATE: XXH64_state_t = XXH64_state_t {
        total_len: 0,
        v: [0; 4],
        mem64: [0; 4],
        memsize: 0,
        reserved32: 0,
        reserved64: 0,
    };

    unsafe fn compress_end_test_context(
        context: *mut c_void,
    ) -> &'static mut CompressEndTestContext {
        unsafe { &mut *context.cast::<CompressEndTestContext>() }
    }

    unsafe extern "C" fn compress_end_test_frame_prepare_overflow(
        _context: *mut c_void,
        _src: *const c_void,
        _block_size: usize,
    ) {
    }

    unsafe extern "C" fn compress_end_test_frame_prepare_window(
        _context: *mut c_void,
        _src: *const c_void,
        _block_size: usize,
        _max_dist: c_uint,
    ) {
    }

    unsafe extern "C" fn compress_end_test_frame_target(
        context: *mut c_void,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        last_block: c_uint,
    ) -> usize {
        let context = unsafe { compress_end_test_context(context) };
        context.events.push("continue");
        context.continue_frame = 1;
        context.continue_last_frame_chunk = last_block;
        context.continue_result
    }

    unsafe extern "C" fn compress_end_test_trace(context: *mut c_void, extra_c_size: usize) {
        let context = unsafe { compress_end_test_context(context) };
        context.events.push("trace");
        context.trace_extra = extra_c_size;
    }

    fn compress_end_test_state(
        context: &mut CompressEndTestContext,
        consumed_src_size: &mut u64,
        pledged_src_size_plus_one: u64,
        content_size_flag: c_int,
    ) -> ZSTD_rust_compressEndState {
        let base = WINDOW_INIT_SENTINEL.as_ptr().cast::<c_void>();
        context.stage = ZSTD_COMPRESSION_STAGE_ONGOING;
        context.window = ZSTD_rust_windowUpdateState {
            nextSrc: base,
            base,
            dictBase: base,
            dictLimit: ZSTD_WINDOW_START_INDEX,
            lowLimit: ZSTD_WINDOW_START_INDEX,
        };
        context.force_non_contiguous = 0;
        context.next_to_update = ZSTD_WINDOW_START_INDEX;
        context.is_first_block = 1;
        context.produced_c_size = 0;
        context.window_projection = ZSTD_rust_compressContinueWindowProjection {
            next_src: ptr::addr_of_mut!(context.window.nextSrc),
            base: ptr::addr_of_mut!(context.window.base),
            dict_base: ptr::addr_of_mut!(context.window.dictBase),
            dict_limit: ptr::addr_of_mut!(context.window.dictLimit),
            low_limit: ptr::addr_of_mut!(context.window.lowLimit),
            force_non_contiguous: ptr::addr_of_mut!(context.force_non_contiguous),
            next_to_update: ptr::addr_of_mut!(context.next_to_update),
        };
        let callback_context = (context as *mut CompressEndTestContext).cast();
        context.frame_chunk_clamp_state = Some(ZSTD_rust_frameChunkClampState {
            next_to_update: ptr::addr_of_mut!(context.next_to_update),
            low_limit: ptr::addr_of!(context.window.lowLimit),
        });
        let frame_chunk_clamp_state = context
            .frame_chunk_clamp_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.frame_chunk_prepare_state = Some(ZSTD_rust_frameChunkPrepareState {
            callback_context,
            max_dist: 64,
            correct_overflow: compress_end_test_frame_prepare_overflow,
            check_dict_validity: compress_end_test_frame_prepare_window,
            enforce_max_dist: compress_end_test_frame_prepare_window,
            clamp_state: frame_chunk_clamp_state,
        });
        let frame_chunk_prepare_state = context
            .frame_chunk_prepare_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.frame_chunk_state = Some(ZSTD_rust_frameChunkState {
            callback_context,
            tmp_workspace: ptr::null_mut(),
            checksum_state: ptr::null_mut(),
            is_first_block: ptr::addr_of_mut!(context.is_first_block),
            stage: ptr::addr_of_mut!(context.stage),
            tmp_wksp_size: 0,
            block_size_max: 1,
            savings: 0,
            pre_block_splitter_level: 1,
            strategy: ZSTD_FAST,
            use_target_c_block_size: 1,
            block_splitter_enabled: 0,
            checksum_flag: 0,
            ending_stage: ZSTD_COMPRESSION_STAGE_ENDING,
            prepare_state: frame_chunk_prepare_state,
            compress_target: Some(compress_end_test_frame_target),
            compress_split: Some(compress_end_test_frame_target),
            compress_internal: Some(compress_end_test_frame_target),
            compress_internal_state: ptr::null(),
            compress_target_state: ptr::null(),
            compress_split_state: ptr::null(),
            derive_block_splits_state: ptr::null(),
        });
        let frame_chunk_state = context
            .frame_chunk_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.continue_state = Some(ZSTD_rust_compressContinueState {
            callback_context,
            window_state: &context.window_projection,
            ldm_window_state: ptr::null(),
            overflow_state: ptr::null(),
            frame_chunk_state,
            compress_block: compress_end_test_frame_target,
            stage: ptr::addr_of_mut!(context.stage),
            consumed_src_size: consumed_src_size as *mut u64,
            produced_c_size: ptr::addr_of_mut!(context.produced_c_size),
            pledged_src_size_plus_one,
            block_size_max: 1,
            check_block_size: 0,
            no_dict_id_flag: 0,
            checksum_flag: 0,
            content_size_flag: 0,
            format: 0,
            window_log: 20,
            dict_id: 0,
            ldm_enabled: 0,
        });
        let continue_state = context
            .continue_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        ZSTD_rust_compressEndState {
            callback_context,
            compress_continue_state: continue_state,
            trace: compress_end_test_trace,
            consumed_src_size: consumed_src_size as *const u64,
            pledged_src_size_plus_one,
            content_size_flag,
            stage: &mut context.stage,
            no_dict_id_flag: 0,
            checksum_flag: 1,
            format: 0,
            window_log: 20,
            checksum_state: &COMPRESS_END_TEST_CHECKSUM_STATE,
        }
    }

    #[test]
    fn compress_end_preserves_callback_order_and_output_accounting() {
        let mut dst = [0u8; 32];
        let mut context = CompressEndTestContext {
            continue_result: 3,
            ..CompressEndTestContext::default()
        };
        let mut consumed_src_size = 7;
        let state = compress_end_test_state(&mut context, &mut consumed_src_size, 9, 1);
        let source = [0u8; 1];

        let result = unsafe {
            ZSTD_rust_compressEnd(
                &state,
                dst.as_mut_ptr().cast(),
                dst.len(),
                source.as_ptr().cast(),
                source.len(),
            )
        };

        assert_eq!(result, 7);
        assert_eq!(context.events, ["continue", "trace"]);
        assert_eq!(
            (context.continue_frame, context.continue_last_frame_chunk),
            (1, 1)
        );
        assert_eq!(context.trace_extra, 4);
        assert_eq!((consumed_src_size, context.produced_c_size), (8, 3));
        assert_eq!(context.stage, 0);
    }

    #[test]
    fn compress_end_stops_before_epilogue_when_continue_fails() {
        let mut dst = [0u8; 16];
        let mut context = CompressEndTestContext {
            continue_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..CompressEndTestContext::default()
        };
        let mut consumed_src_size = 7;
        let state = compress_end_test_state(&mut context, &mut consumed_src_size, 8, 0);
        let source = [0u8; 1];

        let result = unsafe {
            ZSTD_rust_compressEnd(
                &state,
                dst.as_mut_ptr().cast(),
                dst.len(),
                source.as_ptr().cast(),
                source.len(),
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["continue"]);
    }

    #[test]
    fn compress_end_stops_before_validation_and_trace_when_epilogue_fails() {
        let mut dst = [0u8; 6];
        let mut context = CompressEndTestContext {
            continue_result: 3,
            ..CompressEndTestContext::default()
        };
        let mut consumed_src_size = 7;
        let state = compress_end_test_state(&mut context, &mut consumed_src_size, 99, 1);
        let source = [0u8; 1];

        let result = unsafe {
            ZSTD_rust_compressEnd(
                &state,
                dst.as_mut_ptr().cast(),
                dst.len(),
                source.as_ptr().cast(),
                source.len(),
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::DstSizeTooSmall));
        assert_eq!(context.events, ["continue"]);
    }

    #[test]
    fn compress_end_rejects_pledged_size_before_trace() {
        let mut dst = [0u8; 32];
        let mut context = CompressEndTestContext {
            continue_result: 3,
            ..CompressEndTestContext::default()
        };
        let mut consumed_src_size = 7;
        let state = compress_end_test_state(&mut context, &mut consumed_src_size, 99, 1);
        let source = [0u8; 1];

        let result = unsafe {
            ZSTD_rust_compressEnd(
                &state,
                dst.as_mut_ptr().cast(),
                dst.len(),
                source.as_ptr().cast(),
                source.len(),
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::SrcSizeWrong));
        assert_eq!(context.events, ["continue"]);
    }

    #[derive(Default)]
    struct CompressStreamInitTestContext {
        events: Vec<&'static str>,
        local_create_result: usize,
        create_result: usize,
        mt_result: usize,
        begin_result: usize,
        pledged: u64,
        local_dict: *const c_void,
        local_dict_buffer: *mut c_void,
        local_dict_size: usize,
        local_dict_content_type: c_int,
        local_cdict: *mut c_void,
        context_cdict: *const c_void,
        prefix_dict: *const c_void,
        created_local_cdict: *mut c_void,
        cdict: *const c_void,
        cdict_is_local: c_int,
        cdict_compression_level: c_int,
        cdict_dict_content_size: usize,
        expected_prefix: *const c_void,
        nb_workers: c_uint,
        has_ext_seq_prod: c_int,
        mt_context: *mut c_void,
        buffer_mode: c_int,
        block_size: usize,
        ordinary_target: usize,
        compression_level: c_int,
    }

    unsafe fn compress_stream_init_test_context(
        context: *mut c_void,
    ) -> &'static mut CompressStreamInitTestContext {
        unsafe { &mut *context.cast::<CompressStreamInitTestContext>() }
    }

    unsafe extern "C" fn compress_stream_init_test_get_local_dict(
        context: *mut c_void,
        local_dict: *mut ZSTD_rust_compressStreamInitLocalDictState,
    ) {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("local-dict");
        let local_dict = unsafe { &mut *local_dict };
        local_dict.dict = context.local_dict;
        local_dict.dict_buffer = context.local_dict_buffer;
        local_dict.dict_size = context.local_dict_size;
        local_dict.dict_content_type = context.local_dict_content_type;
        local_dict.local_cdict = context.local_cdict;
        local_dict.cdict = context.context_cdict;
        local_dict.prefix_dict = context.prefix_dict;
        local_dict.created_cdict = ptr::null_mut();
    }

    unsafe extern "C" fn compress_stream_init_test_create_local_dict(
        context: *mut c_void,
        local_dict: *mut ZSTD_rust_compressStreamInitLocalDictState,
    ) -> usize {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("create-local-dict");
        unsafe { &mut *local_dict }.created_cdict = context.created_local_cdict;
        context.local_create_result
    }

    unsafe extern "C" fn compress_stream_init_test_publish_local_dict(
        context: *mut c_void,
        local_dict: *const ZSTD_rust_compressStreamInitLocalDictState,
    ) {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("publish-local-dict");
        let local_dict = unsafe { &*local_dict };
        context.local_cdict = local_dict.created_cdict;
        context.context_cdict = local_dict.created_cdict.cast_const();
        context.cdict = local_dict.created_cdict.cast_const();
    }

    unsafe extern "C" fn compress_stream_init_test_refresh_cdict(
        context: *mut c_void,
        dictionaries: *mut ZSTD_rust_compressStreamInitDictionaryState,
    ) {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("refresh-cdict");
        let dictionaries = unsafe { &mut *dictionaries };
        dictionaries.cdict = context.cdict;
        dictionaries.cdict_is_local = context.cdict_is_local;
        dictionaries.cdict_compression_level = context.cdict_compression_level;
        dictionaries.cdict_dict_content_size = context.cdict_dict_content_size;
    }

    unsafe extern "C" fn compress_stream_init_test_clear_prefix(context: *mut c_void) {
        unsafe { compress_stream_init_test_context(context) }
            .events
            .push("clear-prefix");
    }

    unsafe extern "C" fn compress_stream_init_test_assert_dictionaries(
        context: *mut c_void,
        prefix: *const c_void,
    ) {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("assert-dictionaries");
        assert_eq!(prefix, context.expected_prefix);
    }

    unsafe extern "C" fn compress_stream_init_test_set_level(params: *mut c_void, level: c_int) {
        let context = unsafe { &mut *params.cast::<CompressStreamInitTestContext>() };
        context.events.push("set-level");
        context.compression_level = level;
    }

    unsafe extern "C" fn compress_stream_init_test_debug(context: *mut c_void) {
        unsafe { compress_stream_init_test_context(context) }
            .events
            .push("debug");
    }

    unsafe extern "C" fn compress_stream_init_test_get_pledged(context: *mut c_void) -> u64 {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("get-pledged");
        context.pledged
    }

    unsafe extern "C" fn compress_stream_init_test_set_pledged(
        context: *mut c_void,
        in_size: usize,
    ) {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("set-pledged");
        context.pledged = (in_size as u64).wrapping_add(1);
    }

    unsafe extern "C" fn compress_stream_init_test_get_cparam_mode(
        params: *mut c_void,
        _cdict: *const c_void,
        _pledged: u64,
    ) -> c_int {
        unsafe { compress_stream_init_test_context(params) }
            .events
            .push("get-cparam-mode");
        0
    }

    unsafe extern "C" fn compress_stream_init_test_build_cparams(
        params: *mut c_void,
        _pledged: u64,
        _dict_size: usize,
        _mode: c_int,
    ) {
        unsafe { compress_stream_init_test_context(params) }
            .events
            .push("build-cparams");
    }

    unsafe extern "C" fn compress_stream_init_test_resolve_params(
        params: *mut c_void,
        operation: c_int,
    ) {
        let context = unsafe { compress_stream_init_test_context(params) };
        context.events.push(match operation {
            ZSTD_RUST_INIT_RESOLVE_BLOCK_SPLITTER => "resolve:block-splitter",
            ZSTD_RUST_INIT_RESOLVE_LDM => "resolve:ldm",
            ZSTD_RUST_INIT_RESOLVE_ROW_MATCH_FINDER => "resolve:row-match-finder",
            ZSTD_RUST_INIT_RESOLVE_VALIDATE_SEQUENCES => "resolve:validate-sequences",
            ZSTD_RUST_INIT_RESOLVE_MAX_BLOCK_SIZE => "resolve:max-block-size",
            ZSTD_RUST_INIT_RESOLVE_EXTERNAL_REPCODE_SEARCH => "resolve:external-repcodes",
            _ => "resolve:unknown",
        });
    }

    unsafe extern "C" fn compress_stream_init_test_get_nb_workers(params: *mut c_void) -> c_uint {
        let context = unsafe { compress_stream_init_test_context(params) };
        context.events.push("get-workers");
        context.nb_workers
    }

    unsafe extern "C" fn compress_stream_init_test_set_nb_workers(
        params: *mut c_void,
        nb_workers: c_uint,
    ) {
        let context = unsafe { compress_stream_init_test_context(params) };
        context.events.push("set-workers");
        context.nb_workers = nb_workers;
    }

    unsafe extern "C" fn compress_stream_init_test_has_ext_seq_prod(params: *mut c_void) -> c_int {
        let context = unsafe { compress_stream_init_test_context(params) };
        context.events.push("has-ext-seq-prod");
        context.has_ext_seq_prod
    }

    unsafe extern "C" fn compress_stream_init_test_trace(context: *mut c_void) {
        unsafe { compress_stream_init_test_context(context) }
            .events
            .push("trace");
    }

    unsafe extern "C" fn compress_stream_init_test_get_mt_context(
        context: *mut c_void,
    ) -> *mut c_void {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("get-mt-context");
        context.mt_context
    }

    unsafe extern "C" fn compress_stream_init_test_create_mt_context(
        context: *mut c_void,
        _nb_workers: c_uint,
    ) -> usize {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("create-mt-context");
        if !ERR_isError(context.create_result) {
            context.mt_context = ptr::dangling_mut::<c_void>();
        }
        context.create_result
    }

    unsafe extern "C" fn compress_stream_init_test_mt(
        context: *mut c_void,
        _mt_context: *mut c_void,
        _dictionaries: *const ZSTD_rust_compressStreamInitDictionaryState,
        _params: *mut c_void,
        _pledged: u64,
    ) -> usize {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("init-mt");
        context.mt_result
    }

    unsafe extern "C" fn compress_stream_init_test_commit_mt(
        context: *mut c_void,
        _dictionaries: *const ZSTD_rust_compressStreamInitDictionaryState,
        _params: *mut c_void,
    ) {
        unsafe { compress_stream_init_test_context(context) }
            .events
            .push("commit-mt");
    }

    unsafe extern "C" fn compress_stream_init_test_check_cparams(params: *mut c_void) {
        unsafe { compress_stream_init_test_context(params) }
            .events
            .push("check-cparams");
    }

    unsafe extern "C" fn compress_stream_init_test_begin(
        context: *mut c_void,
        _dictionaries: *const ZSTD_rust_compressStreamInitDictionaryState,
        _params: *mut c_void,
        _pledged: u64,
    ) -> usize {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("compress-begin");
        context.begin_result
    }

    unsafe extern "C" fn compress_stream_init_test_assert_ordinary(context: *mut c_void) {
        unsafe { compress_stream_init_test_context(context) }
            .events
            .push("assert-ordinary");
    }

    unsafe extern "C" fn compress_stream_init_test_get_buffer_mode(context: *mut c_void) -> c_int {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("get-buffer-mode");
        context.buffer_mode
    }

    unsafe extern "C" fn compress_stream_init_test_get_block_size(context: *mut c_void) -> usize {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("get-block-size");
        context.block_size
    }

    unsafe extern "C" fn compress_stream_init_test_commit_ordinary(
        context: *mut c_void,
        in_buff_target: usize,
    ) {
        let context = unsafe { compress_stream_init_test_context(context) };
        context.events.push("commit-ordinary");
        context.ordinary_target = in_buff_target;
    }

    fn compress_stream_init_test_state(
        context: &mut CompressStreamInitTestContext,
        dictionaries: &mut ZSTD_rust_compressStreamInitDictionaryState,
        end_op: c_int,
        in_size: usize,
        multithreaded: c_int,
    ) -> ZSTD_rust_compressStreamInitState {
        ZSTD_rust_compressStreamInitState {
            callback_context: (context as *mut CompressStreamInitTestContext).cast(),
            params: (context as *mut CompressStreamInitTestContext).cast(),
            dictionaries,
            end_op,
            in_size,
            multithreaded,
            mt_job_size_min: 10,
            get_local_dict: compress_stream_init_test_get_local_dict,
            create_local_dict: compress_stream_init_test_create_local_dict,
            publish_local_dict: compress_stream_init_test_publish_local_dict,
            refresh_cdict: compress_stream_init_test_refresh_cdict,
            clear_prefix: compress_stream_init_test_clear_prefix,
            assert_dictionaries: compress_stream_init_test_assert_dictionaries,
            set_compression_level: compress_stream_init_test_set_level,
            debug_init: compress_stream_init_test_debug,
            get_pledged_src_size_plus_one: compress_stream_init_test_get_pledged,
            set_pledged_src_size: compress_stream_init_test_set_pledged,
            get_cparam_mode: compress_stream_init_test_get_cparam_mode,
            build_cparams: compress_stream_init_test_build_cparams,
            resolve_params: compress_stream_init_test_resolve_params,
            get_nb_workers: compress_stream_init_test_get_nb_workers,
            set_nb_workers: compress_stream_init_test_set_nb_workers,
            has_ext_seq_prod: compress_stream_init_test_has_ext_seq_prod,
            trace_begin: compress_stream_init_test_trace,
            get_mt_context: compress_stream_init_test_get_mt_context,
            create_mt_context: compress_stream_init_test_create_mt_context,
            init_mt: compress_stream_init_test_mt,
            commit_mt: compress_stream_init_test_commit_mt,
            check_cparams: compress_stream_init_test_check_cparams,
            compress_begin: compress_stream_init_test_begin,
            assert_ordinary: compress_stream_init_test_assert_ordinary,
            get_buffer_mode: compress_stream_init_test_get_buffer_mode,
            get_block_size: compress_stream_init_test_get_block_size,
            commit_ordinary: compress_stream_init_test_commit_ordinary,
        }
    }

    #[test]
    fn compress_stream_init_preserves_ordinary_callback_order_and_policy() {
        let mut context = CompressStreamInitTestContext {
            pledged: 0,
            cdict: ptr::dangling::<c_void>(),
            cdict_compression_level: 17,
            cdict_dict_content_size: 3,
            nb_workers: 0,
            buffer_mode: ZSTD_BM_BUFFERED,
            block_size: 4,
            ..CompressStreamInitTestContext::default()
        };
        let mut dictionaries = ZSTD_rust_compressStreamInitDictionaryState {
            prefix_dict: ptr::null(),
            prefix_dict_size: 0,
            prefix_dict_content_type: 0,
            cdict: ptr::null(),
            cdict_is_local: 0,
            cdict_compression_level: 0,
            cdict_dict_content_size: 0,
        };
        let state =
            compress_stream_init_test_state(&mut context, &mut dictionaries, ZSTD_E_END, 4, 0);

        let result = unsafe { ZSTD_rust_compressStreamInit(&state) };

        assert_eq!(result, 0);
        assert_eq!(context.compression_level, 17);
        assert_eq!(context.pledged, 5);
        assert_eq!(context.ordinary_target, 5);
        assert_eq!(
            context.events,
            [
                "local-dict",
                "refresh-cdict",
                "clear-prefix",
                "assert-dictionaries",
                "set-level",
                "debug",
                "set-pledged",
                "get-pledged",
                "get-cparam-mode",
                "build-cparams",
                "resolve:block-splitter",
                "resolve:ldm",
                "resolve:row-match-finder",
                "resolve:validate-sequences",
                "resolve:max-block-size",
                "resolve:external-repcodes",
                "check-cparams",
                "compress-begin",
                "assert-ordinary",
                "get-buffer-mode",
                "get-block-size",
                "commit-ordinary",
            ]
        );
    }

    #[test]
    fn compress_stream_init_orchestrates_local_dictionary_creation_and_publish() {
        let mut context = CompressStreamInitTestContext {
            local_dict: ptr::dangling::<c_void>(),
            local_dict_size: 3,
            created_local_cdict: ptr::dangling_mut::<c_void>(),
            cdict_is_local: 1,
            cdict_dict_content_size: 3,
            buffer_mode: ZSTD_BM_BUFFERED,
            block_size: 4,
            ..CompressStreamInitTestContext::default()
        };
        let mut dictionaries = ZSTD_rust_compressStreamInitDictionaryState {
            prefix_dict: ptr::null(),
            prefix_dict_size: 0,
            prefix_dict_content_type: 0,
            cdict: ptr::null(),
            cdict_is_local: 0,
            cdict_compression_level: 0,
            cdict_dict_content_size: 0,
        };
        let state =
            compress_stream_init_test_state(&mut context, &mut dictionaries, ZSTD_E_CONTINUE, 0, 0);

        let result = unsafe { ZSTD_rust_compressStreamInit(&state) };

        assert_eq!(result, 0);
        assert_eq!(context.local_cdict, context.created_local_cdict);
        assert_eq!(
            context.context_cdict,
            context.created_local_cdict.cast_const()
        );
        assert_eq!(
            &context.events[..3],
            ["local-dict", "create-local-dict", "publish-local-dict"]
        );
        assert_eq!(context.events[3], "refresh-cdict");
        assert_eq!(dictionaries.cdict, context.created_local_cdict.cast_const());
        assert_eq!(dictionaries.cdict_is_local, 1);
    }

    #[test]
    fn compress_stream_init_stops_before_later_callbacks_on_error() {
        let mut context = CompressStreamInitTestContext {
            local_dict: ptr::dangling::<c_void>(),
            local_dict_size: 3,
            local_create_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..CompressStreamInitTestContext::default()
        };
        let mut dictionaries = ZSTD_rust_compressStreamInitDictionaryState {
            prefix_dict: ptr::null(),
            prefix_dict_size: 0,
            prefix_dict_content_type: 0,
            cdict: ptr::null(),
            cdict_is_local: 0,
            cdict_compression_level: 0,
            cdict_dict_content_size: 0,
        };
        let state =
            compress_stream_init_test_state(&mut context, &mut dictionaries, ZSTD_E_CONTINUE, 0, 0);

        let result = unsafe { ZSTD_rust_compressStreamInit(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["local-dict", "create-local-dict"]);
    }

    #[test]
    fn compress_stream_init_preserves_mt_branch_and_init_error_order() {
        let mut context = CompressStreamInitTestContext {
            cdict: ptr::dangling::<c_void>(),
            cdict_dict_content_size: 3,
            nb_workers: 2,
            mt_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..CompressStreamInitTestContext::default()
        };
        let mut dictionaries = ZSTD_rust_compressStreamInitDictionaryState {
            prefix_dict: ptr::null(),
            prefix_dict_size: 0,
            prefix_dict_content_type: 0,
            cdict: ptr::null(),
            cdict_is_local: 0,
            cdict_compression_level: 0,
            cdict_dict_content_size: 0,
        };
        let state =
            compress_stream_init_test_state(&mut context, &mut dictionaries, ZSTD_E_END, 99, 1);

        let result = unsafe { ZSTD_rust_compressStreamInit(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(
            context.events,
            [
                "local-dict",
                "refresh-cdict",
                "clear-prefix",
                "assert-dictionaries",
                "set-level",
                "debug",
                "set-pledged",
                "get-pledged",
                "get-cparam-mode",
                "build-cparams",
                "resolve:block-splitter",
                "resolve:ldm",
                "resolve:row-match-finder",
                "resolve:validate-sequences",
                "resolve:max-block-size",
                "resolve:external-repcodes",
                "has-ext-seq-prod",
                "get-workers",
                "trace",
                "get-mt-context",
                "create-mt-context",
                "get-mt-context",
                "init-mt",
            ]
        );
    }

    fn system_round_trip(compressed: &[u8]) -> Option<Vec<u8>> {
        let mut child = Command::new("zstd")
            .args(["-q", "-d", "-c"])
            .stdin(Stdio::piped())
            .stdout(Stdio::piped())
            .stderr(Stdio::piped())
            .spawn()
            .ok()?;
        child.stdin.take()?.write_all(compressed).ok()?;
        let output = child.wait_with_output().ok()?;
        if !output.status.success() {
            panic!(
                "system zstd rejected Rust output: {}",
                String::from_utf8_lossy(&output.stderr)
            );
        }
        Some(output.stdout)
    }

    fn compress_input(input: &[u8], level: c_int) -> Vec<u8> {
        let capacity = crate::zstd_compress_api::ZSTD_compressBound(input.len());
        assert!(!ERR_isError(capacity));
        let mut output = vec![0u8; capacity];
        let written = unsafe {
            ZSTD_compress(
                output.as_mut_ptr().cast(),
                output.len(),
                input.as_ptr().cast(),
                input.len(),
                level,
            )
        };
        assert!(!ERR_isError(written));
        output.truncate(written);
        output
    }

    #[derive(Default)]
    struct FrameChunkTestContext {
        prepare_calls: usize,
        prepared_sizes: [usize; 4],
        prepare_order: [u8; 16],
        prepare_order_len: usize,
        prepare_max_dist: c_uint,
        prepare_state: Option<ZSTD_rust_frameChunkPrepareState>,
        clamp_state: Option<ZSTD_rust_frameChunkClampState>,
        clamp_next_to_update: c_uint,
        clamp_low_limit: c_uint,
        target_calls: usize,
        split_calls: usize,
        internal_calls: usize,
        last_blocks: [c_uint; 4],
        checksum_state: Option<XXH64_state_t>,
        target_result: usize,
        split_result: usize,
        internal_result: usize,
    }

    unsafe fn frame_chunk_test_context(context: *mut c_void) -> &'static mut FrameChunkTestContext {
        unsafe { &mut *context.cast::<FrameChunkTestContext>() }
    }

    unsafe fn frame_chunk_test_record_prepare(context: *mut c_void, step: u8, block_size: usize) {
        let context = unsafe { frame_chunk_test_context(context) };
        if context.prepare_order_len < context.prepare_order.len() {
            context.prepare_order[context.prepare_order_len] = step;
        }
        context.prepare_order_len += 1;
        if step == 1 {
            if context.prepare_calls < context.prepared_sizes.len() {
                context.prepared_sizes[context.prepare_calls] = block_size;
            }
            context.prepare_calls += 1;
        }
    }

    unsafe extern "C" fn frame_chunk_test_correct_overflow(
        context: *mut c_void,
        _src: *const c_void,
        block_size: usize,
    ) {
        unsafe { frame_chunk_test_record_prepare(context, 1, block_size) };
    }

    unsafe extern "C" fn frame_chunk_test_check_dict_validity(
        context: *mut c_void,
        _src: *const c_void,
        block_size: usize,
        max_dist: c_uint,
    ) {
        unsafe { frame_chunk_test_record_prepare(context, 2, block_size) };
        unsafe { frame_chunk_test_context(context) }.prepare_max_dist = max_dist;
    }

    unsafe extern "C" fn frame_chunk_test_enforce_max_dist(
        context: *mut c_void,
        _src: *const c_void,
        block_size: usize,
        max_dist: c_uint,
    ) {
        unsafe { frame_chunk_test_record_prepare(context, 3, block_size) };
        unsafe { frame_chunk_test_context(context) }.prepare_max_dist = max_dist;
    }

    unsafe extern "C" fn frame_chunk_test_target(
        context: *mut c_void,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        last_block: c_uint,
    ) -> usize {
        let context = unsafe { frame_chunk_test_context(context) };
        if context.target_calls < context.last_blocks.len() {
            context.last_blocks[context.target_calls] = last_block;
        }
        context.target_calls += 1;
        context.target_result
    }

    unsafe extern "C" fn frame_chunk_test_split(
        context: *mut c_void,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        last_block: c_uint,
    ) -> usize {
        let context = unsafe { frame_chunk_test_context(context) };
        if context.split_calls < context.last_blocks.len() {
            context.last_blocks[context.split_calls] = last_block;
        }
        context.split_calls += 1;
        context.split_result
    }

    unsafe extern "C" fn frame_chunk_test_internal(
        context: *mut c_void,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        last_block: c_uint,
    ) -> usize {
        let context = unsafe { frame_chunk_test_context(context) };
        if context.internal_calls < context.last_blocks.len() {
            context.last_blocks[context.internal_calls] = last_block;
        }
        context.internal_calls += 1;
        context.internal_result
    }

    fn frame_chunk_test_state(
        context: &mut FrameChunkTestContext,
        is_first_block: &mut c_int,
        stage: &mut c_int,
        use_target_c_block_size: c_int,
        block_splitter_enabled: c_int,
        checksum_flag: c_int,
    ) -> ZSTD_rust_frameChunkState {
        let context_ptr = context as *mut FrameChunkTestContext;
        let callback_context = context_ptr.cast::<c_void>();
        context.checksum_state = Some(XXH64_state_t {
            total_len: 0,
            v: [0; 4],
            mem64: [0; 4],
            memsize: 0,
            reserved32: 0,
            reserved64: 0,
        });
        let checksum_state = context.checksum_state.as_mut().unwrap();
        unsafe {
            let _ = XXH64_reset(checksum_state, 0);
        }
        unsafe {
            (*context_ptr).clamp_state = Some(ZSTD_rust_frameChunkClampState {
                next_to_update: &mut (*context_ptr).clamp_next_to_update,
                low_limit: &(*context_ptr).clamp_low_limit,
            });
            (*context_ptr).prepare_state = Some(ZSTD_rust_frameChunkPrepareState {
                callback_context,
                max_dist: 64,
                correct_overflow: frame_chunk_test_correct_overflow,
                check_dict_validity: frame_chunk_test_check_dict_validity,
                enforce_max_dist: frame_chunk_test_enforce_max_dist,
                clamp_state: (*context_ptr)
                    .clamp_state
                    .as_ref()
                    .map_or(ptr::null(), |state| state as *const _),
            });
        }
        let prepare_state = unsafe {
            (*context_ptr)
                .prepare_state
                .as_ref()
                .map_or(ptr::null(), |state| state as *const _)
        };
        ZSTD_rust_frameChunkState {
            callback_context,
            tmp_workspace: ptr::null_mut(),
            checksum_state,
            is_first_block,
            stage,
            tmp_wksp_size: 0,
            block_size_max: 4,
            savings: 0,
            pre_block_splitter_level: 1,
            strategy: ZSTD_FAST,
            use_target_c_block_size,
            block_splitter_enabled,
            checksum_flag,
            ending_stage: 77,
            prepare_state,
            compress_target: Some(frame_chunk_test_target),
            compress_split: Some(frame_chunk_test_split),
            compress_internal: Some(frame_chunk_test_internal),
            compress_internal_state: ptr::null(),
            compress_target_state: ptr::null(),
            compress_split_state: ptr::null(),
            derive_block_splits_state: ptr::null(),
        }
    }

    #[test]
    fn frame_chunk_internal_path_emits_blocks_and_updates_state_once() {
        let mut context = FrameChunkTestContext {
            internal_result: 2,
            clamp_next_to_update: 1,
            clamp_low_limit: 4,
            ..FrameChunkTestContext::default()
        };
        let mut is_first_block = 1;
        let mut stage = 0;
        let state = frame_chunk_test_state(&mut context, &mut is_first_block, &mut stage, 0, 0, 1);
        let source = [0x11u8; 8];
        let mut output = [0xa5u8; 16];

        let result = unsafe {
            compress_frame_chunk_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
            )
        };

        assert_eq!(result, 10);
        assert_eq!(context.prepare_calls, 2);
        assert_eq!(context.prepared_sizes[..2], [4, 4]);
        assert_eq!(context.prepare_order[..6], [1, 2, 3, 1, 2, 3]);
        assert_eq!(context.prepare_max_dist, 64);
        assert_eq!(context.clamp_next_to_update, 4);
        assert_eq!(context.internal_calls, 2);
        assert_eq!(context.last_blocks[..2], [0, 1]);
        assert_eq!(
            context.checksum_state.as_ref().unwrap().total_len,
            source.len() as u64
        );
        assert_eq!(is_first_block, 0);
        assert_eq!(stage, 77);
        assert_ne!(output[..3], [0xa5; 3]);
        assert_ne!(output[5..8], [0xa5; 3]);
    }

    #[test]
    fn frame_chunk_dispatches_target_and_split_paths_before_internal() {
        let source = [0x22u8; 4];

        let mut target_context = FrameChunkTestContext {
            target_result: 4,
            split_result: 5,
            internal_result: 6,
            ..FrameChunkTestContext::default()
        };
        let mut target_first = 1;
        let mut target_stage = 0;
        let target_state = frame_chunk_test_state(
            &mut target_context,
            &mut target_first,
            &mut target_stage,
            1,
            1,
            0,
        );
        let mut target_output = [0xa5u8; 8];
        let target_result = unsafe {
            compress_frame_chunk_body_with(
                &target_state,
                target_output.as_mut_ptr().cast(),
                target_output.len(),
                source.as_ptr().cast(),
                source.len(),
                0,
            )
        };
        assert_eq!(target_result, 4);
        assert_eq!(target_context.target_calls, 1);
        assert_eq!(target_context.split_calls, 0);
        assert_eq!(target_context.internal_calls, 0);

        let mut split_context = FrameChunkTestContext {
            split_result: 5,
            internal_result: 6,
            ..FrameChunkTestContext::default()
        };
        let mut split_first = 1;
        let mut split_stage = 0;
        let split_state = frame_chunk_test_state(
            &mut split_context,
            &mut split_first,
            &mut split_stage,
            0,
            1,
            0,
        );
        let mut split_output = [0xa5u8; 8];
        let split_result = unsafe {
            compress_frame_chunk_body_with(
                &split_state,
                split_output.as_mut_ptr().cast(),
                split_output.len(),
                source.as_ptr().cast(),
                source.len(),
                0,
            )
        };
        assert_eq!(split_result, 5);
        assert_eq!(split_context.target_calls, 0);
        assert_eq!(split_context.split_calls, 1);
        assert_eq!(split_context.internal_calls, 0);
    }

    #[test]
    fn frame_chunk_keeps_state_unchanged_on_early_capacity_error() {
        let mut context = FrameChunkTestContext::default();
        let mut is_first_block = 1;
        let mut stage = 23;
        let state = frame_chunk_test_state(&mut context, &mut is_first_block, &mut stage, 0, 0, 1);
        let source = [0x33u8; 4];
        let mut output = [0xa5u8; 5];

        let result = unsafe {
            compress_frame_chunk_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::DstSizeTooSmall));
        assert_eq!(
            context.checksum_state.as_ref().unwrap().total_len,
            source.len() as u64
        );
        assert_eq!(context.prepare_calls, 0);
        assert_eq!(context.internal_calls, 0);
        assert_eq!(is_first_block, 1);
        assert_eq!(stage, 23);
        assert_eq!(output, [0xa5; 5]);
    }

    #[derive(Default)]
    struct CompressContinueTestContext {
        overflow_calls: usize,
        frame_calls: usize,
        block_calls: usize,
        last_frame_chunk: c_uint,
        frame_result: usize,
        block_result: usize,
        window: ZSTD_rust_windowUpdateState,
        ldm_window: ZSTD_rust_windowUpdateState,
        force_non_contiguous: c_int,
        next_to_update: c_uint,
        loaded_dict_end: c_uint,
        dict_match_state: *const c_void,
        window_projection: ZSTD_rust_compressContinueWindowProjection,
        ldm_window_projection: ZSTD_rust_compressContinueWindowProjection,
        overflow_state: Option<ZSTD_rust_overflowCorrectState>,
        is_first_block: c_int,
        frame_chunk_clamp_state: Option<ZSTD_rust_frameChunkClampState>,
        frame_chunk_prepare_state: Option<ZSTD_rust_frameChunkPrepareState>,
        frame_chunk_state: Option<ZSTD_rust_frameChunkState>,
    }

    unsafe fn compress_continue_test_context(
        context: *mut c_void,
    ) -> &'static mut CompressContinueTestContext {
        unsafe { &mut *context.cast::<CompressContinueTestContext>() }
    }

    unsafe extern "C" fn compress_continue_test_overflow_need(
        context: *mut c_void,
        _src: *const c_void,
        _src_end: *const c_void,
    ) -> c_int {
        let context = unsafe { compress_continue_test_context(context) };
        context.overflow_calls += 1;
        0
    }

    unsafe extern "C" fn compress_continue_test_overflow_correct(
        _context: *mut c_void,
        _src: *const c_void,
    ) -> c_uint {
        0
    }

    unsafe extern "C" fn compress_continue_test_overflow_callback(_context: *mut c_void) {}

    unsafe extern "C" fn compress_continue_test_overflow_reduce(
        _context: *mut c_void,
        _correction: c_uint,
    ) {
    }

    unsafe extern "C" fn compress_continue_test_frame_prepare_overflow(
        _context: *mut c_void,
        _src: *const c_void,
        _block_size: usize,
    ) {
    }

    unsafe extern "C" fn compress_continue_test_frame_prepare_window(
        _context: *mut c_void,
        _src: *const c_void,
        _block_size: usize,
        _max_dist: c_uint,
    ) {
    }

    unsafe extern "C" fn compress_continue_test_frame(
        context: *mut c_void,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        last_frame_chunk: c_uint,
    ) -> usize {
        let context = unsafe { compress_continue_test_context(context) };
        context.frame_calls += 1;
        context.last_frame_chunk = last_frame_chunk;
        context.frame_result
    }

    unsafe extern "C" fn compress_continue_test_block(
        context: *mut c_void,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        _last_frame_chunk: c_uint,
    ) -> usize {
        let context = unsafe { compress_continue_test_context(context) };
        context.block_calls += 1;
        context.block_result
    }

    fn compress_continue_test_state(
        context: &mut CompressContinueTestContext,
        stage: &mut c_int,
        consumed_src_size: &mut u64,
        produced_c_size: &mut u64,
        pledged_src_size_plus_one: u64,
        block_size_max: usize,
        check_block_size: c_int,
    ) -> ZSTD_rust_compressContinueState {
        let base = WINDOW_INIT_SENTINEL.as_ptr().cast::<c_void>();
        let next_src = unsafe { base.cast::<u8>().add(2).cast::<c_void>() };
        context.window = ZSTD_rust_windowUpdateState {
            nextSrc: next_src,
            base,
            dictBase: base,
            dictLimit: ZSTD_WINDOW_START_INDEX,
            lowLimit: ZSTD_WINDOW_START_INDEX,
        };
        context.ldm_window = context.window;
        context.force_non_contiguous = 0;
        context.next_to_update = ZSTD_WINDOW_START_INDEX;
        context.loaded_dict_end = 0;
        context.dict_match_state = ptr::null();
        context.is_first_block = 1;
        context.window_projection = ZSTD_rust_compressContinueWindowProjection {
            next_src: ptr::addr_of_mut!(context.window.nextSrc),
            base: ptr::addr_of_mut!(context.window.base),
            dict_base: ptr::addr_of_mut!(context.window.dictBase),
            dict_limit: ptr::addr_of_mut!(context.window.dictLimit),
            low_limit: ptr::addr_of_mut!(context.window.lowLimit),
            force_non_contiguous: ptr::addr_of_mut!(context.force_non_contiguous),
            next_to_update: ptr::addr_of_mut!(context.next_to_update),
        };
        context.ldm_window_projection = ZSTD_rust_compressContinueWindowProjection {
            next_src: ptr::addr_of_mut!(context.ldm_window.nextSrc),
            base: ptr::addr_of_mut!(context.ldm_window.base),
            dict_base: ptr::addr_of_mut!(context.ldm_window.dictBase),
            dict_limit: ptr::addr_of_mut!(context.ldm_window.dictLimit),
            low_limit: ptr::addr_of_mut!(context.ldm_window.lowLimit),
            force_non_contiguous: ptr::null_mut(),
            next_to_update: ptr::null_mut(),
        };
        let callback_context = (context as *mut CompressContinueTestContext).cast();
        context.overflow_state = Some(ZSTD_rust_overflowCorrectState {
            callback_context,
            next_to_update: ptr::addr_of_mut!(context.next_to_update),
            need_correction: Some(compress_continue_test_overflow_need),
            correct_overflow: Some(compress_continue_test_overflow_correct),
            mark_tables_dirty: Some(compress_continue_test_overflow_callback),
            reduce_index: Some(compress_continue_test_overflow_reduce),
            mark_tables_clean: Some(compress_continue_test_overflow_callback),
            loaded_dict_end: ptr::addr_of_mut!(context.loaded_dict_end),
            dict_match_state: ptr::addr_of_mut!(context.dict_match_state),
        });
        let overflow_state = context
            .overflow_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.frame_chunk_clamp_state = Some(ZSTD_rust_frameChunkClampState {
            next_to_update: ptr::addr_of_mut!(context.next_to_update),
            low_limit: ptr::addr_of!(context.window.lowLimit),
        });
        let frame_chunk_clamp_state = context
            .frame_chunk_clamp_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.frame_chunk_prepare_state = Some(ZSTD_rust_frameChunkPrepareState {
            callback_context,
            max_dist: 64,
            correct_overflow: compress_continue_test_frame_prepare_overflow,
            check_dict_validity: compress_continue_test_frame_prepare_window,
            enforce_max_dist: compress_continue_test_frame_prepare_window,
            clamp_state: frame_chunk_clamp_state,
        });
        let frame_chunk_prepare_state = context
            .frame_chunk_prepare_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.frame_chunk_state = Some(ZSTD_rust_frameChunkState {
            callback_context,
            tmp_workspace: ptr::null_mut(),
            checksum_state: ptr::null_mut(),
            is_first_block: ptr::addr_of_mut!(context.is_first_block),
            stage,
            tmp_wksp_size: 0,
            block_size_max,
            savings: 0,
            pre_block_splitter_level: 1,
            strategy: ZSTD_FAST,
            use_target_c_block_size: 1,
            block_splitter_enabled: 0,
            checksum_flag: 0,
            ending_stage: ZSTD_COMPRESSION_STAGE_ENDING,
            prepare_state: frame_chunk_prepare_state,
            compress_target: Some(compress_continue_test_frame),
            compress_split: Some(compress_continue_test_frame),
            compress_internal: Some(compress_continue_test_frame),
            compress_internal_state: ptr::null(),
            compress_target_state: ptr::null(),
            compress_split_state: ptr::null(),
            derive_block_splits_state: ptr::null(),
        });
        let frame_chunk_state = context
            .frame_chunk_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        ZSTD_rust_compressContinueState {
            callback_context,
            window_state: &context.window_projection,
            ldm_window_state: &context.ldm_window_projection,
            overflow_state,
            frame_chunk_state,
            compress_block: compress_continue_test_block,
            stage,
            consumed_src_size,
            produced_c_size,
            pledged_src_size_plus_one,
            block_size_max,
            check_block_size,
            no_dict_id_flag: 0,
            checksum_flag: 0,
            content_size_flag: 0,
            format: 0,
            window_log: 10,
            dict_id: 0,
            ldm_enabled: 1,
        }
    }

    #[test]
    fn compress_continue_block_builds_small_block_through_projected_states() {
        let mut probe = BuildSeqStoreSelectProbe::default();
        let mut seq_store = unsafe { MaybeUninit::<SeqStore_t>::zeroed().assume_init() };
        let mut build_state = build_seq_store_select_test_state(&mut probe, 0, 0, 0, 0);
        build_state.seq_store = &mut seq_store;

        let mut prev_block = zeroed_state();
        let mut next_block = zeroed_state();
        let mut prev_c_block = &mut prev_block as *mut _;
        let mut next_c_block = &mut next_block as *mut _;
        let mut seq_collector = SeqCollector {
            collectSequences: 0,
            seqStart: ptr::null_mut(),
            seqIndex: 0,
            maxSequences: 0,
        };
        let block_state = ZSTD_rust_blockInternalState {
            seq_store: &seq_store,
            prev_c_block: &mut prev_c_block,
            next_c_block: &mut next_c_block,
            tmp_workspace: ptr::null_mut(),
            tmp_wksp_size: 0,
            seq_collector: &mut seq_collector,
            strategy: 0,
            disable_literal_compression: 0,
            bmi2: 0,
            is_first_block: 1,
        };
        let state = ZSTD_rust_compressContinueBlockState {
            build_seq_store_state: &build_state,
            block_internal_state: &block_state,
        };
        let source = [0u8; 1];
        let mut output = [0xa5u8; 8];

        let result = unsafe {
            ZSTD_rust_compressContinueBlock(
                (&state as *const ZSTD_rust_compressContinueBlockState)
                    .cast_mut()
                    .cast(),
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                0,
            )
        };

        assert_eq!(result, 0);
        assert_eq!(output, [0xa5; 8]);
    }

    #[test]
    fn compress_continue_starts_frame_and_updates_progression() {
        let mut context = CompressContinueTestContext {
            frame_result: 6,
            ..CompressContinueTestContext::default()
        };
        let mut stage = ZSTD_COMPRESSION_STAGE_INIT;
        let mut consumed = 7;
        let mut produced = 11;
        let state = compress_continue_test_state(
            &mut context,
            &mut stage,
            &mut consumed,
            &mut produced,
            0,
            16,
            0,
        );
        let source = [0x11u8; 5];
        let mut output = [0xa5u8; 32];

        let result = unsafe {
            ZSTD_rust_compressContinue(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
                1,
            )
        };

        assert_eq!(result, 12);
        assert_eq!(stage, ZSTD_COMPRESSION_STAGE_ENDING);
        assert_eq!(consumed, 12);
        assert_eq!(produced, 23);
        assert_eq!(context.window.nextSrc, unsafe {
            source.as_ptr().add(source.len()).cast()
        });
        assert_eq!(context.ldm_window.nextSrc, context.window.nextSrc);
        assert_eq!(context.force_non_contiguous, 0);
        assert_eq!(context.next_to_update, context.window.dictLimit);
        assert_eq!(context.overflow_calls, 0);
        assert_eq!(context.frame_calls, 1);
        assert_eq!(context.block_calls, 0);
        assert_eq!(context.last_frame_chunk, 1);
        assert_eq!(context.is_first_block, 0);
    }

    #[test]
    fn compress_continue_empty_frame_only_writes_header() {
        let mut context = CompressContinueTestContext::default();
        let mut stage = ZSTD_COMPRESSION_STAGE_INIT;
        let mut consumed = 7;
        let mut produced = 11;
        let state = compress_continue_test_state(
            &mut context,
            &mut stage,
            &mut consumed,
            &mut produced,
            0,
            16,
            0,
        );
        let mut output = [0xa5u8; 18];

        let result = unsafe {
            ZSTD_rust_compressContinue(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                ptr::null(),
                0,
                1,
                0,
            )
        };

        assert_eq!(result, 6);
        assert_eq!(stage, ZSTD_COMPRESSION_STAGE_ONGOING);
        assert_eq!((consumed, produced), (7, 11));
        assert_eq!(context.frame_calls, 0);
        assert_eq!(&output[..6], &[0x28, 0xb5, 0x2f, 0xfd, 0x00, 0x00]);
        assert_eq!(&output[6..], &[0xa5; 12]);
    }

    #[test]
    fn compress_continue_rejects_invalid_stage_and_oversized_block_before_callbacks() {
        let mut context = CompressContinueTestContext::default();
        let mut stage = ZSTD_COMPRESSION_STAGE_INIT;
        let mut consumed = 4;
        let mut produced = 9;
        let mut state = compress_continue_test_state(
            &mut context,
            &mut stage,
            &mut consumed,
            &mut produced,
            0,
            4,
            1,
        );
        let source = [0x22u8; 5];
        let mut output = [0xa5u8; 16];
        let initial_window = context.window;
        let initial_ldm_window = context.ldm_window;

        let oversized = unsafe {
            ZSTD_rust_compressContinue(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                0,
                0,
            )
        };
        assert_eq!(oversized, ERROR(ZstdErrorCode::SrcSizeWrong));
        assert_eq!(stage, ZSTD_COMPRESSION_STAGE_INIT);
        assert_eq!((consumed, produced), (4, 9));
        assert_eq!(context.window, initial_window);
        assert_eq!(context.ldm_window, initial_ldm_window);
        assert_eq!(context.block_calls, 0);

        state.check_block_size = 0;
        stage = ZSTD_COMPRESSION_STAGE_CREATED;
        let created = unsafe {
            ZSTD_rust_compressContinue(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                0,
                0,
            )
        };
        assert_eq!(created, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(stage, ZSTD_COMPRESSION_STAGE_CREATED);
        assert_eq!(context.window, initial_window);
        assert_eq!(context.ldm_window, initial_ldm_window);
        assert_eq!(context.block_calls, 0);
    }

    #[test]
    fn compress_continue_propagates_block_error_without_progression() {
        let mut context = CompressContinueTestContext {
            block_result: ERROR(ZstdErrorCode::DstSizeTooSmall),
            ..CompressContinueTestContext::default()
        };
        let mut stage = ZSTD_COMPRESSION_STAGE_ONGOING;
        let mut consumed = 4;
        let mut produced = 9;
        let state = compress_continue_test_state(
            &mut context,
            &mut stage,
            &mut consumed,
            &mut produced,
            0,
            16,
            0,
        );
        let source = [0x33u8; 5];
        let mut output = [0xa5u8; 16];

        let result = unsafe {
            ZSTD_rust_compressContinue(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                0,
                0,
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::DstSizeTooSmall));
        assert_eq!(
            (stage, consumed, produced),
            (ZSTD_COMPRESSION_STAGE_ONGOING, 4, 9)
        );
        assert_eq!(context.window.nextSrc, unsafe {
            source.as_ptr().add(source.len()).cast()
        });
        assert_eq!(context.ldm_window.nextSrc, context.window.nextSrc);
        assert_eq!(context.overflow_calls, 1);
        assert_eq!(context.block_calls, 1);
    }

    #[test]
    fn compress_continue_reports_pledge_overrun_after_updating_counters() {
        let mut context = CompressContinueTestContext {
            block_result: 3,
            ..CompressContinueTestContext::default()
        };
        let mut stage = ZSTD_COMPRESSION_STAGE_ONGOING;
        let mut consumed = 0;
        let mut produced = 0;
        let state = compress_continue_test_state(
            &mut context,
            &mut stage,
            &mut consumed,
            &mut produced,
            6,
            16,
            0,
        );
        let source = [0x44u8; 6];
        let mut output = [0xa5u8; 16];

        let result = unsafe {
            ZSTD_rust_compressContinue(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                0,
                0,
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::SrcSizeWrong));
        assert_eq!((consumed, produced), (6, 3));
        assert_eq!(context.window.nextSrc, unsafe {
            source.as_ptr().add(source.len()).cast()
        });
        assert_eq!(context.block_calls, 1);
    }

    #[derive(Default)]
    struct CompressStreamTestContext {
        continue_calls: usize,
        end_calls: usize,
        reset_calls: usize,
        continue_result: usize,
        end_result: usize,
        reset_result: usize,
        window: ZSTD_rust_windowUpdateState,
        force_non_contiguous: c_int,
        next_to_update: c_uint,
        window_projection: ZSTD_rust_compressContinueWindowProjection,
        frame_chunk_clamp_state: Option<ZSTD_rust_frameChunkClampState>,
        frame_chunk_prepare_state: Option<ZSTD_rust_frameChunkPrepareState>,
        continue_frame_chunk_state: Option<ZSTD_rust_frameChunkState>,
        end_frame_chunk_state: Option<ZSTD_rust_frameChunkState>,
        continue_state: Option<ZSTD_rust_compressContinueState>,
        end_continue_state: Option<ZSTD_rust_compressContinueState>,
        end_state: Option<ZSTD_rust_compressEndState>,
        compression_stage: c_int,
        is_first_block: c_int,
        end_is_first_block: c_int,
        consumed_src_size: u64,
        produced_c_size: u64,
    }

    unsafe fn compress_stream_test_context(
        context: *mut c_void,
    ) -> &'static mut CompressStreamTestContext {
        unsafe { &mut *context.cast::<CompressStreamTestContext>() }
    }

    unsafe extern "C" fn compress_stream_test_block(
        context: *mut c_void,
        dst: *mut c_void,
        dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        _last_block: c_uint,
    ) -> usize {
        let context = unsafe { compress_stream_test_context(context) };
        context.continue_calls += 1;
        if !ERR_isError(context.continue_result) && context.continue_result != 0 {
            assert!(context.continue_result <= dst_capacity);
            unsafe { ptr::write_bytes(dst.cast::<u8>(), 0x5a, context.continue_result) };
        }
        context.continue_result
    }

    unsafe extern "C" fn compress_stream_test_end(
        context: *mut c_void,
        dst: *mut c_void,
        dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        _last_block: c_uint,
    ) -> usize {
        let context = unsafe { compress_stream_test_context(context) };
        context.end_calls += 1;
        if !ERR_isError(context.end_result) && context.end_result != 0 {
            assert!(context.end_result <= dst_capacity);
            unsafe { ptr::write_bytes(dst.cast::<u8>(), 0x3c, context.end_result) };
        }
        context.end_result
    }

    unsafe extern "C" fn compress_stream_test_reset(context: *mut c_void) -> usize {
        let context = unsafe { compress_stream_test_context(context) };
        context.reset_calls += 1;
        context.reset_result
    }

    unsafe extern "C" fn compress_stream_test_frame_prepare_overflow(
        _context: *mut c_void,
        _src: *const c_void,
        _block_size: usize,
    ) {
    }

    unsafe extern "C" fn compress_stream_test_frame_prepare_window(
        _context: *mut c_void,
        _src: *const c_void,
        _block_size: usize,
        _max_dist: c_uint,
    ) {
    }

    unsafe extern "C" fn compress_stream_test_trace(_context: *mut c_void, _extra_c_size: usize) {}

    #[allow(clippy::too_many_arguments)]
    fn compress_stream_test_state(
        context: &mut CompressStreamTestContext,
        in_buffer_mode: c_int,
        out_buffer_mode: c_int,
        stage: &mut c_int,
        block_size_max: usize,
        stable_in_not_consumed: &mut usize,
        in_buff: *mut c_void,
        in_buff_size: usize,
        in_to_compress: &mut usize,
        in_buff_pos: &mut usize,
        in_buff_target: &mut usize,
        out_buff: *mut c_void,
        out_buff_size: usize,
        out_buff_content_size: &mut usize,
        out_buff_flushed_size: &mut usize,
        frame_ended: &mut c_uint,
    ) -> ZSTD_rust_compressStreamState {
        let base = WINDOW_INIT_SENTINEL.as_ptr().cast::<c_void>();
        context.window = ZSTD_rust_windowUpdateState {
            nextSrc: base,
            base,
            dictBase: base,
            dictLimit: ZSTD_WINDOW_START_INDEX,
            lowLimit: ZSTD_WINDOW_START_INDEX,
        };
        context.force_non_contiguous = 0;
        context.next_to_update = ZSTD_WINDOW_START_INDEX;
        context.compression_stage = ZSTD_COMPRESSION_STAGE_ONGOING;
        context.is_first_block = 1;
        context.end_is_first_block = 1;
        context.consumed_src_size = 0;
        context.produced_c_size = 0;
        context.window_projection = ZSTD_rust_compressContinueWindowProjection {
            next_src: ptr::addr_of_mut!(context.window.nextSrc),
            base: ptr::addr_of_mut!(context.window.base),
            dict_base: ptr::addr_of_mut!(context.window.dictBase),
            dict_limit: ptr::addr_of_mut!(context.window.dictLimit),
            low_limit: ptr::addr_of_mut!(context.window.lowLimit),
            force_non_contiguous: ptr::addr_of_mut!(context.force_non_contiguous),
            next_to_update: ptr::addr_of_mut!(context.next_to_update),
        };
        let callback_context = (context as *mut CompressStreamTestContext).cast();
        context.frame_chunk_clamp_state = Some(ZSTD_rust_frameChunkClampState {
            next_to_update: ptr::addr_of_mut!(context.next_to_update),
            low_limit: ptr::addr_of!(context.window.lowLimit),
        });
        let frame_chunk_clamp_state = context
            .frame_chunk_clamp_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.frame_chunk_prepare_state = Some(ZSTD_rust_frameChunkPrepareState {
            callback_context,
            max_dist: 64,
            correct_overflow: compress_stream_test_frame_prepare_overflow,
            check_dict_validity: compress_stream_test_frame_prepare_window,
            enforce_max_dist: compress_stream_test_frame_prepare_window,
            clamp_state: frame_chunk_clamp_state,
        });
        let frame_chunk_prepare_state = context
            .frame_chunk_prepare_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.continue_frame_chunk_state = Some(ZSTD_rust_frameChunkState {
            callback_context,
            tmp_workspace: ptr::null_mut(),
            checksum_state: ptr::null_mut(),
            is_first_block: ptr::addr_of_mut!(context.is_first_block),
            stage: ptr::addr_of_mut!(context.compression_stage),
            tmp_wksp_size: 0,
            block_size_max,
            savings: 0,
            pre_block_splitter_level: 1,
            strategy: ZSTD_FAST,
            use_target_c_block_size: 1,
            block_splitter_enabled: 0,
            checksum_flag: 0,
            ending_stage: ZSTD_COMPRESSION_STAGE_ENDING,
            prepare_state: frame_chunk_prepare_state,
            compress_target: Some(compress_stream_test_block),
            compress_split: Some(compress_stream_test_block),
            compress_internal: Some(compress_stream_test_block),
            compress_internal_state: ptr::null(),
            compress_target_state: ptr::null(),
            compress_split_state: ptr::null(),
            derive_block_splits_state: ptr::null(),
        });
        let continue_frame_chunk_state = context
            .continue_frame_chunk_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.end_frame_chunk_state = Some(ZSTD_rust_frameChunkState {
            callback_context,
            tmp_workspace: ptr::null_mut(),
            checksum_state: ptr::null_mut(),
            is_first_block: ptr::addr_of_mut!(context.end_is_first_block),
            stage: ptr::addr_of_mut!(context.compression_stage),
            tmp_wksp_size: 0,
            block_size_max,
            savings: 0,
            pre_block_splitter_level: 1,
            strategy: ZSTD_FAST,
            use_target_c_block_size: 1,
            block_splitter_enabled: 0,
            checksum_flag: 0,
            ending_stage: ZSTD_COMPRESSION_STAGE_ENDING,
            prepare_state: frame_chunk_prepare_state,
            compress_target: Some(compress_stream_test_end),
            compress_split: Some(compress_stream_test_end),
            compress_internal: Some(compress_stream_test_end),
            compress_internal_state: ptr::null(),
            compress_target_state: ptr::null(),
            compress_split_state: ptr::null(),
            derive_block_splits_state: ptr::null(),
        });
        let end_frame_chunk_state = context
            .end_frame_chunk_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.continue_state = Some(ZSTD_rust_compressContinueState {
            callback_context,
            window_state: &context.window_projection,
            ldm_window_state: ptr::null(),
            overflow_state: ptr::null(),
            frame_chunk_state: continue_frame_chunk_state,
            compress_block: compress_stream_test_block,
            stage: ptr::addr_of_mut!(context.compression_stage),
            consumed_src_size: ptr::addr_of_mut!(context.consumed_src_size),
            produced_c_size: ptr::addr_of_mut!(context.produced_c_size),
            pledged_src_size_plus_one: 0,
            block_size_max,
            check_block_size: 0,
            no_dict_id_flag: 0,
            checksum_flag: 0,
            content_size_flag: 0,
            format: 0,
            window_log: 20,
            dict_id: 0,
            ldm_enabled: 0,
        });
        let continue_state = context
            .continue_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.end_continue_state = Some(ZSTD_rust_compressContinueState {
            callback_context,
            window_state: &context.window_projection,
            ldm_window_state: ptr::null(),
            overflow_state: ptr::null(),
            frame_chunk_state: end_frame_chunk_state,
            compress_block: compress_stream_test_end,
            stage: ptr::addr_of_mut!(context.compression_stage),
            consumed_src_size: ptr::addr_of_mut!(context.consumed_src_size),
            produced_c_size: ptr::addr_of_mut!(context.produced_c_size),
            pledged_src_size_plus_one: 0,
            block_size_max,
            check_block_size: 0,
            no_dict_id_flag: 0,
            checksum_flag: 0,
            content_size_flag: 0,
            format: 0,
            window_log: 20,
            dict_id: 0,
            ldm_enabled: 0,
        });
        let end_continue_state = context
            .end_continue_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        context.end_state = Some(ZSTD_rust_compressEndState {
            callback_context,
            compress_continue_state: end_continue_state,
            trace: compress_stream_test_trace,
            consumed_src_size: ptr::addr_of!(context.consumed_src_size),
            pledged_src_size_plus_one: 0,
            content_size_flag: 0,
            stage: ptr::addr_of_mut!(context.compression_stage),
            no_dict_id_flag: 0,
            checksum_flag: 0,
            format: 0,
            window_log: 20,
            checksum_state: &COMPRESS_END_TEST_CHECKSUM_STATE,
        });
        let end_state = context
            .end_state
            .as_ref()
            .map_or(ptr::null(), |state| state as *const _);
        ZSTD_rust_compressStreamState {
            callback_context,
            in_buffer_mode,
            out_buffer_mode,
            stream_stage: stage,
            block_size_max,
            stable_in_not_consumed,
            in_buff,
            in_buff_size,
            in_to_compress,
            in_buff_pos,
            in_buff_target,
            out_buff,
            out_buff_size,
            out_buff_content_size,
            out_buff_flushed_size,
            frame_ended,
            compress_continue_state: continue_state,
            compress_end_state: end_state,
            reset_session: compress_stream_test_reset,
        }
    }

    #[test]
    fn compress_stream_stable_short_input_is_deferred_with_a_progress_hint() {
        let mut context = CompressStreamTestContext::default();
        let mut stage = ZSTD_CSTREAM_STAGE_LOAD;
        let mut stable_in_not_consumed = 0;
        let mut in_to_compress = 0;
        let mut in_buff_pos = 0;
        let mut in_buff_target = 0;
        let mut out_buff_content_size = 0;
        let mut out_buff_flushed_size = 0;
        let mut frame_ended = 0;
        let state = compress_stream_test_state(
            &mut context,
            ZSTD_BM_STABLE,
            ZSTD_BM_STABLE,
            &mut stage,
            8,
            &mut stable_in_not_consumed,
            ptr::null_mut(),
            0,
            &mut in_to_compress,
            &mut in_buff_pos,
            &mut in_buff_target,
            ptr::null_mut(),
            0,
            &mut out_buff_content_size,
            &mut out_buff_flushed_size,
            &mut frame_ended,
        );
        let source = [1u8, 2, 3];
        let mut output = [0xa5u8; 8];
        let mut input = ZSTD_inBuffer {
            src: source.as_ptr().cast(),
            size: source.len(),
            pos: 0,
        };
        let mut output_buffer = ZSTD_outBuffer {
            dst: output.as_mut_ptr().cast(),
            size: output.len(),
            pos: 0,
        };

        let result = unsafe {
            ZSTD_rust_compressStreamGeneric(&state, &mut output_buffer, &mut input, ZSTD_E_CONTINUE)
        };

        assert_eq!(result, 5);
        assert_eq!(input.pos, source.len());
        assert_eq!(stable_in_not_consumed, source.len());
        assert_eq!(output_buffer.pos, 0);
        assert_eq!(context.continue_calls, 0);
        assert_eq!(context.end_calls, 0);
        assert_eq!(frame_ended, 0);
    }

    #[test]
    fn compress_stream_buffered_output_preserves_pending_flush_and_drains_it() {
        let mut context = CompressStreamTestContext {
            continue_result: 3,
            ..CompressStreamTestContext::default()
        };
        let mut stage = ZSTD_CSTREAM_STAGE_LOAD;
        let mut stable_in_not_consumed = 0;
        let mut in_to_compress = 0;
        let mut in_buff_pos = 0;
        let mut in_buff_target = 4;
        let mut out_buff_content_size = 0;
        let mut out_buff_flushed_size = 0;
        let mut frame_ended = 0;
        let mut input_buffer = [0u8; 8];
        let mut internal_output = [0xa5u8; 8];
        let state = compress_stream_test_state(
            &mut context,
            ZSTD_BM_BUFFERED,
            ZSTD_BM_BUFFERED,
            &mut stage,
            4,
            &mut stable_in_not_consumed,
            input_buffer.as_mut_ptr().cast(),
            input_buffer.len(),
            &mut in_to_compress,
            &mut in_buff_pos,
            &mut in_buff_target,
            internal_output.as_mut_ptr().cast(),
            internal_output.len(),
            &mut out_buff_content_size,
            &mut out_buff_flushed_size,
            &mut frame_ended,
        );
        let source = [1u8, 2, 3, 4];
        let mut output = [0xa5u8; 2];
        let mut input = ZSTD_inBuffer {
            src: source.as_ptr().cast(),
            size: source.len(),
            pos: 0,
        };
        let mut output_buffer = ZSTD_outBuffer {
            dst: output.as_mut_ptr().cast(),
            size: output.len(),
            pos: 0,
        };

        let result = unsafe {
            ZSTD_rust_compressStreamGeneric(&state, &mut output_buffer, &mut input, ZSTD_E_CONTINUE)
        };

        assert_eq!(result, 4);
        assert_eq!(input.pos, source.len());
        assert_eq!(output_buffer.pos, output.len());
        assert_eq!(output, [0x5a; 2]);
        assert_eq!(out_buff_content_size, 3);
        assert_eq!(out_buff_flushed_size, 2);
        assert_eq!(stage, ZSTD_CSTREAM_STAGE_FLUSH);
        assert_eq!(context.continue_calls, 1);

        let mut next_output = [0xa5u8; 2];
        output_buffer = ZSTD_outBuffer {
            dst: next_output.as_mut_ptr().cast(),
            size: next_output.len(),
            pos: 0,
        };
        let result = unsafe {
            ZSTD_rust_compressStreamGeneric(&state, &mut output_buffer, &mut input, ZSTD_E_FLUSH)
        };

        assert_eq!(result, 4);
        assert_eq!(next_output[0], 0x5a);
        assert_eq!(output_buffer.pos, 1);
        assert_eq!((out_buff_content_size, out_buff_flushed_size), (0, 0));
        assert_eq!(stage, ZSTD_CSTREAM_STAGE_LOAD);
        assert_eq!(context.continue_calls, 1);
    }

    #[test]
    fn compress_stream_end_shortcut_resets_after_direct_completion() {
        let mut context = CompressStreamTestContext {
            end_result: 5,
            ..CompressStreamTestContext::default()
        };
        let mut stage = ZSTD_CSTREAM_STAGE_LOAD;
        let mut stable_in_not_consumed = 0;
        let mut in_to_compress = 0;
        let mut in_buff_pos = 0;
        let mut in_buff_target = 4;
        let mut out_buff_content_size = 0;
        let mut out_buff_flushed_size = 0;
        let mut frame_ended = 0;
        let mut input_buffer = [0u8; 8];
        let mut internal_output = [0u8; 8];
        let state = compress_stream_test_state(
            &mut context,
            ZSTD_BM_BUFFERED,
            ZSTD_BM_STABLE,
            &mut stage,
            4,
            &mut stable_in_not_consumed,
            input_buffer.as_mut_ptr().cast(),
            input_buffer.len(),
            &mut in_to_compress,
            &mut in_buff_pos,
            &mut in_buff_target,
            internal_output.as_mut_ptr().cast(),
            internal_output.len(),
            &mut out_buff_content_size,
            &mut out_buff_flushed_size,
            &mut frame_ended,
        );
        let source = [7u8, 8, 9];
        let mut output = [0xa5u8; 8];
        let mut input = ZSTD_inBuffer {
            src: source.as_ptr().cast(),
            size: source.len(),
            pos: 0,
        };
        let mut output_buffer = ZSTD_outBuffer {
            dst: output.as_mut_ptr().cast(),
            size: output.len(),
            pos: 0,
        };

        let result = unsafe {
            ZSTD_rust_compressStreamGeneric(&state, &mut output_buffer, &mut input, ZSTD_E_END)
        };

        assert_eq!(result, 0);
        assert_eq!(input.pos, source.len());
        assert_eq!(output_buffer.pos, 5);
        assert_eq!(&output[..5], &[0x3c; 5]);
        assert_eq!(frame_ended, 1);
        assert_eq!(context.end_calls, 1);
        assert_eq!(context.continue_calls, 0);
        assert_eq!(context.reset_calls, 1);
    }

    #[test]
    fn compress_stream_stable_block_error_consumes_input_before_returning() {
        let mut context = CompressStreamTestContext {
            continue_result: ERROR(ZstdErrorCode::DstSizeTooSmall),
            ..CompressStreamTestContext::default()
        };
        let mut stage = ZSTD_CSTREAM_STAGE_LOAD;
        let mut stable_in_not_consumed = 0;
        let mut in_to_compress = 0;
        let mut in_buff_pos = 0;
        let mut in_buff_target = 0;
        let mut out_buff_content_size = 0;
        let mut out_buff_flushed_size = 0;
        let mut frame_ended = 0;
        let state = compress_stream_test_state(
            &mut context,
            ZSTD_BM_STABLE,
            ZSTD_BM_STABLE,
            &mut stage,
            4,
            &mut stable_in_not_consumed,
            ptr::null_mut(),
            0,
            &mut in_to_compress,
            &mut in_buff_pos,
            &mut in_buff_target,
            ptr::null_mut(),
            0,
            &mut out_buff_content_size,
            &mut out_buff_flushed_size,
            &mut frame_ended,
        );
        let source = [0x11u8; 4];
        let mut output = [0xa5u8; 8];
        let mut input = ZSTD_inBuffer {
            src: source.as_ptr().cast(),
            size: source.len(),
            pos: 0,
        };
        let mut output_buffer = ZSTD_outBuffer {
            dst: output.as_mut_ptr().cast(),
            size: output.len(),
            pos: 0,
        };

        let result = unsafe {
            ZSTD_rust_compressStreamGeneric(&state, &mut output_buffer, &mut input, ZSTD_E_CONTINUE)
        };

        assert_eq!(result, ERROR(ZstdErrorCode::DstSizeTooSmall));
        assert_eq!(input.pos, source.len());
        assert_eq!(output_buffer.pos, 0);
        assert_eq!(context.continue_calls, 1);
        assert_eq!(context.end_calls, 0);
        assert_eq!(context.reset_calls, 0);
        assert_eq!(frame_ended, 0);
    }

    #[test]
    fn compress_stream_rejects_missing_initialization_before_callbacks() {
        let mut context = CompressStreamTestContext::default();
        let mut stage = ZSTD_CSTREAM_STAGE_INIT;
        let mut stable_in_not_consumed = 0;
        let mut in_to_compress = 0;
        let mut in_buff_pos = 0;
        let mut in_buff_target = 0;
        let mut out_buff_content_size = 0;
        let mut out_buff_flushed_size = 0;
        let mut frame_ended = 0;
        let state = compress_stream_test_state(
            &mut context,
            ZSTD_BM_STABLE,
            ZSTD_BM_STABLE,
            &mut stage,
            4,
            &mut stable_in_not_consumed,
            ptr::null_mut(),
            0,
            &mut in_to_compress,
            &mut in_buff_pos,
            &mut in_buff_target,
            ptr::null_mut(),
            0,
            &mut out_buff_content_size,
            &mut out_buff_flushed_size,
            &mut frame_ended,
        );
        let mut input = ZSTD_inBuffer {
            src: ptr::null(),
            size: 0,
            pos: 0,
        };
        let mut output = ZSTD_outBuffer {
            dst: ptr::null_mut(),
            size: 0,
            pos: 0,
        };

        let result = unsafe {
            ZSTD_rust_compressStreamGeneric(&state, &mut output, &mut input, ZSTD_E_FLUSH)
        };

        assert_eq!(result, ERROR(ZstdErrorCode::InitMissing));
        assert_eq!(context.continue_calls, 0);
        assert_eq!(context.end_calls, 0);
        assert_eq!(context.reset_calls, 0);
    }

    #[test]
    fn simple_strategy_follows_source_size_tiers() {
        assert_eq!(ZSTD_rust_compressCCtxStrategy(0, 1), ZSTD_FAST);
        assert_eq!(ZSTD_rust_compressCCtxStrategy(16 * 1024, 5), ZSTD_LAZY);
        assert_eq!(
            ZSTD_rust_compressCCtxStrategy(16 * 1024 + 1, 5),
            ZSTD_GREEDY
        );
        assert_eq!(ZSTD_rust_compressCCtxStrategy(128 * 1024, 16), ZSTD_BTULTRA);
        assert_eq!(ZSTD_rust_compressCCtxStrategy(256 * 1024, 16), ZSTD_BTULTRA);
        assert_eq!(
            ZSTD_rust_compressCCtxStrategy(256 * 1024 + 1, 16),
            ZSTD_BTOPT
        );
    }

    #[test]
    fn simple_strategy_preserves_default_and_fast_level_selection() {
        assert_eq!(ZSTD_rust_compressCCtxStrategy(64 * 1024, 0), ZSTD_DFAST);
        assert_eq!(ZSTD_rust_compressCCtxStrategy(1024 * 1024, -5), ZSTD_FAST);
        assert_eq!(
            ZSTD_rust_compressCCtxStrategy(1024 * 1024, 22),
            ZSTD_BTULTRA2
        );
    }

    #[derive(Default)]
    struct SimpleStreamPolicyTestContext {
        calls: usize,
        src_size: usize,
    }

    unsafe extern "C" fn simple_stream_policy_test_level(
        context: *const c_void,
        src_size: usize,
    ) -> c_int {
        let context = unsafe { &mut *context.cast_mut().cast::<SimpleStreamPolicyTestContext>() };
        context.calls += 1;
        context.src_size = src_size;
        7
    }

    #[test]
    fn simple_stream_policy_calls_the_level_leaf_only_for_a_new_frame() {
        let mut context = SimpleStreamPolicyTestContext::default();
        let cctx = (&mut context as *mut SimpleStreamPolicyTestContext).cast();
        let projection = ZSTD_rust_simpleCompressStream2Projection {
            stream_stage: ZSTD_CSTREAM_STAGE_INIT,
            pledged_src_size_plus_one: 0,
            rust_simple_compress2_completed: 0,
        };

        let result = unsafe {
            ZSTD_rust_simpleCompressStream2Policy(
                &projection,
                cctx,
                123,
                Some(simple_stream_policy_test_level),
            )
        };

        assert_eq!(result, 7);
        assert_eq!(context.calls, 1);
        assert_eq!(context.src_size, 123);
    }

    #[test]
    fn simple_stream_policy_rejects_non_initial_or_completed_frames() {
        let mut context = SimpleStreamPolicyTestContext::default();
        let cctx = (&mut context as *mut SimpleStreamPolicyTestContext).cast();
        for projection in [
            ZSTD_rust_simpleCompressStream2Projection {
                stream_stage: ZSTD_CSTREAM_STAGE_LOAD,
                ..Default::default()
            },
            ZSTD_rust_simpleCompressStream2Projection {
                pledged_src_size_plus_one: 1,
                ..Default::default()
            },
            ZSTD_rust_simpleCompressStream2Projection {
                rust_simple_compress2_completed: 1,
                ..Default::default()
            },
        ] {
            let result = unsafe {
                ZSTD_rust_simpleCompressStream2Policy(
                    &projection,
                    cctx,
                    123,
                    Some(simple_stream_policy_test_level),
                )
            };
            assert_eq!(result, c_int::MIN);
        }
        assert_eq!(context.calls, 0);
    }

    #[test]
    fn reduce_table_applies_threshold_and_wrapping_subtraction() {
        let mut table = [0, 1, 2, 3, 4, 5, 6, u32::MAX, 0, 0, 0, 0, 0, 0, 0, 0];
        reduce_table_internal(&mut table, 3, false);
        assert_eq!(&table[..8], &[0, 0, 0, 0, 0, 2, 3, u32::MAX - 3]);

        let mut wrapped_threshold = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
        reduce_table_internal(&mut wrapped_threshold, u32::MAX, false);
        assert_eq!(wrapped_threshold[0], 0);
        assert_eq!(wrapped_threshold[1], 2);
        assert_eq!(wrapped_threshold[15], 16);
    }

    #[test]
    fn reduce_table_preserves_only_the_btlazy2_mark() {
        let mut ordinary = [0u32; ZSTD_ROWSIZE];
        ordinary[..3].copy_from_slice(&[ZSTD_DUBT_UNSORTED_MARK, 5, 6]);
        reduce_table_internal(&mut ordinary, 3, false);
        assert_eq!(&ordinary[..3], &[0, 2, 3]);

        let mut btlazy2 = [0u32; ZSTD_ROWSIZE];
        btlazy2[..3].copy_from_slice(&[ZSTD_DUBT_UNSORTED_MARK, 5, 6]);
        reduce_table_internal(&mut btlazy2, 3, true);
        assert_eq!(&btlazy2[..3], &[ZSTD_DUBT_UNSORTED_MARK, 2, 3]);
    }

    #[test]
    fn reduce_table_processes_every_cell_in_multiple_rows() {
        let mut table = [0u32; ZSTD_ROWSIZE * 2];
        table[0] = 2;
        table[ZSTD_ROWSIZE - 1] = 8;
        table[ZSTD_ROWSIZE] = 1;
        table[ZSTD_ROWSIZE * 2 - 1] = u32::MAX;

        reduce_table_internal(&mut table, 4, false);

        assert_eq!(table[0], 0);
        assert_eq!(table[ZSTD_ROWSIZE - 1], 4);
        assert_eq!(table[ZSTD_ROWSIZE], 0);
        assert_eq!(table[ZSTD_ROWSIZE * 2 - 1], u32::MAX - 4);
    }

    #[test]
    fn reduce_index_accepts_zero_sized_optional_tables() {
        let mut hash_table = [0u32; ZSTD_ROWSIZE];
        hash_table[..4].copy_from_slice(&[1, 2, 5, u32::MAX]);

        unsafe {
            ZSTD_rust_reduceIndex(
                hash_table.as_mut_ptr(),
                hash_table.len() as u32,
                ptr::null_mut(),
                0,
                ptr::null_mut(),
                0,
                3,
                0,
            );
            ZSTD_rust_reduceIndex(
                ptr::null_mut(),
                0,
                ptr::null_mut(),
                0,
                ptr::null_mut(),
                0,
                u32::MAX,
                1,
            );
        }

        assert_eq!(&hash_table[..4], &[0, 0, 2, u32::MAX - 3]);
    }

    #[test]
    fn reduce_index_preserves_the_marker_only_in_the_chain_table() {
        let mut hash_table = [0u32; ZSTD_ROWSIZE];
        let mut chain_table = [0u32; ZSTD_ROWSIZE];
        let mut hash_table3 = [0u32; ZSTD_ROWSIZE];
        hash_table[0] = ZSTD_DUBT_UNSORTED_MARK;
        chain_table[0] = ZSTD_DUBT_UNSORTED_MARK;
        hash_table3[0] = ZSTD_DUBT_UNSORTED_MARK;

        unsafe {
            ZSTD_rust_reduceIndex(
                hash_table.as_mut_ptr(),
                hash_table.len() as u32,
                chain_table.as_mut_ptr(),
                chain_table.len() as u32,
                hash_table3.as_mut_ptr(),
                hash_table3.len() as u32,
                3,
                1,
            );
        }

        assert_eq!(hash_table[0], 0);
        assert_eq!(chain_table[0], ZSTD_DUBT_UNSORTED_MARK);
        assert_eq!(hash_table3[0], 0);
    }

    #[test]
    fn reduce_index_for_match_state_selects_chain_and_hash3_tables() {
        let mut hash_table = [0u32; ZSTD_ROWSIZE];
        let mut chain_table = [0u32; ZSTD_ROWSIZE];
        let mut hash_table3 = [0u32; ZSTD_ROWSIZE];
        hash_table[0] = ZSTD_DUBT_UNSORTED_MARK;
        chain_table[0] = ZSTD_DUBT_UNSORTED_MARK;
        hash_table3[0] = ZSTD_DUBT_UNSORTED_MARK;

        unsafe {
            ZSTD_rust_reduceIndexForMatchState(
                hash_table.as_mut_ptr(),
                4,
                chain_table.as_mut_ptr(),
                4,
                hash_table3.as_mut_ptr(),
                4,
                ZSTD_BTLAZY2,
                ZSTD_RUST_PS_DISABLE,
                0,
                3,
            );
        }

        assert_eq!(hash_table[0], 0);
        assert_eq!(chain_table[0], ZSTD_DUBT_UNSORTED_MARK);
        assert_eq!(hash_table3[0], 0);
    }

    #[test]
    fn copy_cdict_table_removes_short_cache_tags() {
        let source = [0x1234_56ff, 0xdead_beef, 0x0000_0100, u32::MAX];
        let mut destination = [0u32; 4];

        unsafe {
            ZSTD_rust_copyCDictTableIntoCCtx(
                destination.as_mut_ptr(),
                source.as_ptr(),
                source.len(),
                1,
            );
        }

        assert_eq!(destination, [0x0012_3456, 0x00de_adbe, 1, 0x00ff_ffff]);
    }

    #[test]
    fn copy_cdict_table_preserves_untagged_entries() {
        let source = [0, 2, 0x1234_5678, u32::MAX];
        let mut destination = [0xa5a5_a5a5; 4];

        unsafe {
            ZSTD_rust_copyCDictTableIntoCCtx(
                destination.as_mut_ptr(),
                source.as_ptr(),
                source.len(),
                0,
            );
        }

        assert_eq!(destination, source);
    }

    #[test]
    fn bitmix_and_hash_salt_match_the_c_arithmetic() {
        assert_eq!(bitmix(0x0123_4567_89ab_cdef, 8), 0xd498_d855_4e8d_d8cb);
        assert_eq!(
            advance_hash_salt(0x0123_4567_89ab_cdef, 0xfedc_ba98_7654_3210),
            0xe5ee_f172_e5ff_3e57
        );
        assert_eq!(
            ZSTD_rust_advanceHashSalt(0x0123_4567_89ab_cdef, 0xfedc_ba98_7654_3210),
            0xe5ee_f172_e5ff_3e57
        );
        let mut hash_salt = 0x0123_4567_89ab_cdef;
        unsafe { ZSTD_rust_advanceHashSaltInPlace(&mut hash_salt, 0xfedc_ba98_7654_3210) };
        assert_eq!(hash_salt, 0xe5ee_f172_e5ff_3e57);
    }

    #[test]
    fn index_too_close_to_max_uses_a_strict_margin_boundary() {
        let threshold = ZSTD_CURRENT_MAX - ZSTD_INDEXOVERFLOW_MARGIN;
        assert!(!index_too_close_to_max(threshold));
        assert!(index_too_close_to_max(threshold + 1));
        assert_eq!(ZSTD_indexTooCloseToMax(threshold), 0);
        assert_eq!(ZSTD_indexTooCloseToMax(threshold + 1), 1);
    }

    #[derive(Default)]
    struct OverflowCorrectionTestContext {
        events: Vec<&'static str>,
        should_correct: c_int,
        correction: c_uint,
        loaded_dict_end: c_uint,
        dict_match_state: *const c_void,
    }

    unsafe fn overflow_correction_test_context(
        context: *mut c_void,
    ) -> &'static mut OverflowCorrectionTestContext {
        unsafe { &mut *context.cast::<OverflowCorrectionTestContext>() }
    }

    unsafe extern "C" fn overflow_correction_test_need(
        context: *mut c_void,
        _src: *const c_void,
        _src_end: *const c_void,
    ) -> c_int {
        let context = unsafe { overflow_correction_test_context(context) };
        context.events.push("need");
        context.should_correct
    }

    unsafe extern "C" fn overflow_correction_test_correct(
        context: *mut c_void,
        _src: *const c_void,
    ) -> c_uint {
        let context = unsafe { overflow_correction_test_context(context) };
        context.events.push("correct");
        context.correction
    }

    unsafe extern "C" fn overflow_correction_test_mark_dirty(context: *mut c_void) {
        unsafe { overflow_correction_test_context(context) }
            .events
            .push("dirty");
    }

    unsafe extern "C" fn overflow_correction_test_reduce(
        context: *mut c_void,
        _correction: c_uint,
    ) {
        unsafe { overflow_correction_test_context(context) }
            .events
            .push("reduce");
    }

    unsafe extern "C" fn overflow_correction_test_mark_clean(context: *mut c_void) {
        unsafe { overflow_correction_test_context(context) }
            .events
            .push("clean");
    }

    fn overflow_correction_test_state(
        context: &mut OverflowCorrectionTestContext,
        next_to_update: &mut c_uint,
    ) -> ZSTD_rust_overflowCorrectState {
        ZSTD_rust_overflowCorrectState {
            callback_context: (context as *mut OverflowCorrectionTestContext).cast(),
            next_to_update,
            need_correction: Some(overflow_correction_test_need),
            correct_overflow: Some(overflow_correction_test_correct),
            mark_tables_dirty: Some(overflow_correction_test_mark_dirty),
            reduce_index: Some(overflow_correction_test_reduce),
            mark_tables_clean: Some(overflow_correction_test_mark_clean),
            loaded_dict_end: &mut context.loaded_dict_end,
            dict_match_state: &mut context.dict_match_state,
        }
    }

    #[test]
    fn overflow_correction_preserves_order_and_saturates_next_to_update() {
        let mut context = OverflowCorrectionTestContext {
            should_correct: 1,
            correction: 10,
            loaded_dict_end: 33,
            dict_match_state: ptr::dangling(),
            ..Default::default()
        };
        let mut next_to_update = 7;
        let state = overflow_correction_test_state(&mut context, &mut next_to_update);

        unsafe {
            ZSTD_rust_overflowCorrectIfNeeded(&state, ptr::null(), ptr::null());
        }

        assert_eq!(next_to_update, 0);
        assert_eq!(
            context.events,
            ["need", "correct", "dirty", "reduce", "clean"]
        );
        assert_eq!(context.loaded_dict_end, 0);
        assert!(context.dict_match_state.is_null());
    }

    #[test]
    fn overflow_correction_skips_callbacks_when_window_is_safe() {
        let mut context = OverflowCorrectionTestContext::default();
        let mut next_to_update = 123;
        let state = overflow_correction_test_state(&mut context, &mut next_to_update);

        unsafe {
            ZSTD_rust_overflowCorrectIfNeeded(&state, ptr::null(), ptr::null());
        }

        assert_eq!(next_to_update, 123);
        assert_eq!(context.events, ["need"]);
    }

    #[test]
    fn window_correction_handles_current_cycle_start_boundary() {
        assert_eq!(window_correct_overflow(0x100, 3, 8), 0xf0);
        assert_eq!(window_correct_overflow(0x101, 3, 8), 0xf0);
        assert_eq!(window_correct_overflow(0x102, 3, 8), 0xf8);

        assert_eq!(
            ZSTD_rust_windowCorrectOverflow(0x100, 3, 8),
            window_correct_overflow(0x100, 3, 8)
        );
    }

    #[test]
    fn window_correction_selects_larger_of_cycle_and_max_distance() {
        assert_eq!(window_correct_overflow(0x100, 5, 8), 0xc0);
        assert_eq!(window_correct_overflow(0x200, 5, 64), 0x1a0);
    }

    #[test]
    fn window_correction_wraps_u32_intermediates() {
        assert_eq!(window_correct_overflow(0, 0, 1), u32::MAX - 2);
        assert_eq!(
            window_correct_overflow(0x8000_0000, 31, 0x8000_0000),
            0x8000_0000
        );
        assert_eq!(
            ZSTD_rust_windowCorrectOverflow(0x8000_0000, 31, 0x8000_0000),
            0x8000_0000
        );
    }

    #[test]
    fn window_overflow_need_uses_the_explicit_current_max_boundary() {
        assert!(!window_need_overflow_correction(1024, false, 1024, false));
        assert!(window_need_overflow_correction(1025, false, 1024, false));
        assert_eq!(ZSTD_rust_windowNeedOverflowCorrection(1024, 1, 1024, 0), 0);
        assert_eq!(ZSTD_rust_windowNeedOverflowCorrection(1025, 0, 1024, 0), 1);
    }

    #[test]
    fn window_overflow_need_honors_frequent_dictionary_policy() {
        let can_correct = window_can_overflow_correct(27, 3, 16, 0, 0);
        let dictionary_still_valid = window_can_overflow_correct(27, 3, 16, 20, 0);
        assert!(can_correct);
        assert!(!dictionary_still_valid);
        assert!(window_need_overflow_correction(27, can_correct, 1024, true));
        assert!(!window_need_overflow_correction(
            27,
            dictionary_still_valid,
            1024,
            true
        ));
        assert_eq!(
            ZSTD_rust_windowNeedOverflowCorrection(27, can_correct as u32, 1024, 1),
            1
        );
        assert_eq!(
            ZSTD_rust_windowNeedOverflowCorrection(27, dictionary_still_valid as u32, 1024, 1,),
            0
        );
        assert!(!window_need_overflow_correction(27, true, 1024, false));
    }

    #[test]
    fn limit_next_to_update_preserves_threshold_and_bounded_catch_up() {
        assert_eq!(limit_next_to_update(884, 500), 500);
        assert_eq!(limit_next_to_update(885, 500), 884);
        assert_eq!(limit_next_to_update(1000, 500), 884);
        assert_eq!(limit_next_to_update(1200, 500), 1008);
        assert_eq!(ZSTD_rust_limitNextToUpdate(300, u32::MAX - 100), 283);
    }

    #[test]
    fn window_overflow_need_scales_the_frequency_with_correction_count() {
        assert!(window_can_overflow_correct(27, 3, 16, 0, 0));
        assert!(!window_can_overflow_correct(27, 3, 16, 0, 1));
        assert!(window_can_overflow_correct(53, 3, 16, 0, 1));
        assert_eq!(ZSTD_rust_windowCanOverflowCorrect(53, 3, 16, 0, 1), 1);
    }

    #[test]
    fn window_overflow_need_preserves_u32_wrap_boundaries() {
        assert!(window_can_overflow_correct(
            3,
            31,
            0x8000_0000,
            0x8000_0000,
            0,
        ));
        assert!(window_can_overflow_correct(27, 3, 16, 0, u32::MAX,));
        assert_eq!(
            ZSTD_rust_windowCanOverflowCorrect(3, 31, 0x8000_0000, 0x8000_0000, 0),
            1
        );
    }

    #[test]
    fn dict_too_big_uses_a_strict_chunk_size_boundary() {
        assert!(!dict_too_big(0));
        assert!(!dict_too_big(ZSTD_CHUNKSIZE_MAX));
        assert!(dict_too_big(ZSTD_CHUNKSIZE_MAX + 1));
        assert_eq!(ZSTD_dictTooBig(ZSTD_CHUNKSIZE_MAX), 0);
        assert_eq!(ZSTD_dictTooBig(ZSTD_CHUNKSIZE_MAX + 1), 1);
    }

    #[test]
    fn target_block_policy_requires_compression_and_nonfirst_rle() {
        assert_eq!(
            target_c_block_size_action(0, 0, 1, 1, 0, 128, ZSTD_FAST),
            TargetCBlockAction::Rle
        );
        assert_eq!(
            target_c_block_size_action(0, 1, 1, 1, 0, 128, ZSTD_FAST),
            TargetCBlockAction::Raw
        );
        assert_eq!(
            target_c_block_size_action(0, 0, 0, 1, 0, 128, ZSTD_FAST),
            TargetCBlockAction::Raw
        );
        assert_eq!(
            target_c_block_size_action(0, 0, 1, 0, 0, 128, ZSTD_FAST),
            TargetCBlockAction::Raw
        );
        assert_eq!(
            ZSTD_rust_targetCBlockSizeAction(0, 0, 1, 1, 0, 128, ZSTD_FAST),
            TargetCBlockAction::Rle as c_int
        );
    }

    #[test]
    fn target_block_policy_falls_back_for_uncompressed_and_small_results() {
        assert_eq!(
            target_c_block_size_action(1, 0, 0, 0, 0, 128, ZSTD_FAST),
            TargetCBlockAction::Raw
        );
        assert_eq!(
            target_c_block_size_action(
                ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                0,
                0,
                0,
                ERROR(ZstdErrorCode::DstSizeTooSmall),
                128,
                ZSTD_FAST,
            ),
            TargetCBlockAction::Raw
        );
        assert_eq!(
            target_c_block_size_action(
                ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                0,
                0,
                0,
                ERROR(ZstdErrorCode::Generic),
                128,
                ZSTD_FAST,
            ),
            TargetCBlockAction::Error
        );
        assert_eq!(
            target_c_block_size_action(ZSTD_TARGET_CBLOCK_BSS_COMPRESS, 0, 0, 0, 0, 128, ZSTD_FAST,),
            TargetCBlockAction::Raw
        );
    }

    #[test]
    fn target_block_policy_uses_a_strict_three_byte_header_boundary() {
        let src_size = 128;
        let max_c_size = src_size - min_gain(src_size, ZSTD_FAST);
        let compressed = max_c_size + ZSTD_BLOCK_HEADER_SIZE - 1;
        let raw = max_c_size + ZSTD_BLOCK_HEADER_SIZE;

        assert_eq!(
            target_c_block_size_action(
                ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                0,
                0,
                0,
                compressed,
                src_size,
                ZSTD_FAST,
            ),
            TargetCBlockAction::Compressed
        );
        assert_eq!(
            target_c_block_size_action(
                ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                0,
                0,
                0,
                raw,
                src_size,
                ZSTD_FAST,
            ),
            TargetCBlockAction::Raw
        );
        assert_eq!(
            ZSTD_rust_targetCBlockSizeAction(
                ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                0,
                0,
                0,
                compressed,
                src_size,
                ZSTD_FAST,
            ),
            TargetCBlockAction::Compressed as c_int
        );
    }

    #[allow(clippy::too_many_arguments)]
    unsafe extern "C" fn target_block_test_superblock_error(
        _seq_store: *const c_void,
        _prev_cblock: *const c_void,
        _next_cblock: *mut c_void,
        _strategy: c_int,
        _disable_literal_compression: c_int,
        _workspace: *mut c_void,
        _wksp_size: usize,
        _bmi2: c_int,
        _window_log: c_uint,
        _target_cblock_size: usize,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        _last_block: c_uint,
    ) -> usize {
        ERROR(ZstdErrorCode::Generic)
    }

    #[allow(clippy::too_many_arguments)]
    unsafe extern "C" fn target_block_test_superblock_empty(
        _seq_store: *const c_void,
        _prev_cblock: *const c_void,
        _next_cblock: *mut c_void,
        _strategy: c_int,
        _disable_literal_compression: c_int,
        _workspace: *mut c_void,
        _wksp_size: usize,
        _bmi2: c_int,
        _window_log: c_uint,
        _target_cblock_size: usize,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        _last_block: c_uint,
    ) -> usize {
        0
    }

    #[allow(clippy::too_many_arguments)]
    unsafe extern "C" fn target_block_test_superblock_too_small(
        _seq_store: *const c_void,
        _prev_cblock: *const c_void,
        _next_cblock: *mut c_void,
        _strategy: c_int,
        _disable_literal_compression: c_int,
        _workspace: *mut c_void,
        _wksp_size: usize,
        _bmi2: c_int,
        _window_log: c_uint,
        _target_cblock_size: usize,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        _last_block: c_uint,
    ) -> usize {
        ERROR(ZstdErrorCode::DstSizeTooSmall)
    }

    #[allow(clippy::too_many_arguments)]
    unsafe extern "C" fn target_block_test_superblock_compressed(
        _seq_store: *const c_void,
        _prev_cblock: *const c_void,
        _next_cblock: *mut c_void,
        _strategy: c_int,
        _disable_literal_compression: c_int,
        _workspace: *mut c_void,
        _wksp_size: usize,
        _bmi2: c_int,
        _window_log: c_uint,
        _target_cblock_size: usize,
        _dst: *mut c_void,
        _dst_capacity: usize,
        _src: *const c_void,
        _src_size: usize,
        _last_block: c_uint,
    ) -> usize {
        1
    }

    fn target_block_test_state(
        seq_store: &mut SeqStore_t,
        prev_block: &mut ZSTD_compressedBlockState_t,
        next_block: &mut ZSTD_compressedBlockState_t,
        prev_c_block: &mut *mut ZSTD_compressedBlockState_t,
        next_c_block: &mut *mut ZSTD_compressedBlockState_t,
        is_first_block: c_int,
    ) -> ZSTD_rust_targetCBlockSizeState {
        *prev_c_block = prev_block as *mut ZSTD_compressedBlockState_t;
        *next_c_block = next_block as *mut ZSTD_compressedBlockState_t;
        ZSTD_rust_targetCBlockSizeState {
            seq_store,
            prev_c_block,
            next_c_block,
            tmp_workspace: ptr::null_mut(),
            tmp_wksp_size: 0,
            strategy: ZSTD_FAST,
            disable_literal_compression: 0,
            bmi2: 0,
            window_log: 20,
            target_c_block_size: 0,
            is_first_block,
        }
    }

    fn target_block_test_seq_store() -> (SeqStore_t, [SeqDef; 1], [u8; 16]) {
        let mut sequences = [SeqDef::default(); 1];
        let mut literals = [0u8; 16];
        let sequences_start = sequences.as_mut_ptr();
        let literals_start = literals.as_mut_ptr();
        let seq_store = SeqStore_t {
            sequencesStart: sequences_start,
            sequences: sequences_start,
            litStart: literals_start,
            lit: literals_start,
            llCode: ptr::null_mut(),
            mlCode: ptr::null_mut(),
            ofCode: ptr::null_mut(),
            maxNbSeq: sequences.len(),
            maxNbLit: literals.len(),
            longLengthType: 0,
            longLengthPos: 0,
        };
        (seq_store, sequences, literals)
    }

    #[test]
    fn target_block_body_emits_rle_only_for_nonfirst_repeated_blocks() {
        let (mut seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut prev_block = zeroed_state();
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let state = target_block_test_state(
            &mut seq_store,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            0,
        );
        let source = [0x5au8; 16];
        let mut output = [0xa5u8; 4];

        let result = unsafe {
            compress_block_target_c_block_size_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                1,
                target_block_test_superblock_error,
            )
        };

        assert_eq!(result, 4);
        assert_eq!(output[3], source[0]);
    }

    #[test]
    fn target_block_body_suppresses_first_block_rle_and_propagates_superblock_error() {
        let (mut seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut prev_block = zeroed_state();
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let state = target_block_test_state(
            &mut seq_store,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            1,
        );
        let source = [0x5au8; 16];
        let mut output = [0xa5u8; 16];

        let result = unsafe {
            compress_block_target_c_block_size_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                1,
                target_block_test_superblock_error,
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::Generic));
        assert_eq!(output, [0xa5u8; 16]);
    }

    #[test]
    fn target_block_body_falls_back_to_raw_for_empty_or_small_superblocks() {
        let (mut seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut prev_block = zeroed_state();
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let state = target_block_test_state(
            &mut seq_store,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            1,
        );
        let source = *b"raw fallback";

        for superblock in [
            target_block_test_superblock_empty as TargetCBlockSuperBlockFn,
            target_block_test_superblock_too_small,
        ] {
            let mut output = [0xa5u8; 32];
            let result = unsafe {
                compress_block_target_c_block_size_body_with(
                    &state,
                    output.as_mut_ptr().cast(),
                    output.len(),
                    source.as_ptr().cast(),
                    source.len(),
                    ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                    0,
                    superblock,
                )
            };

            assert_eq!(result, source.len() + ZSTD_BLOCK_HEADER_SIZE);
            assert_eq!(&output[ZSTD_BLOCK_HEADER_SIZE..result], &source);
        }
    }

    #[test]
    fn target_block_body_swaps_state_only_for_compressed_output() {
        let (mut seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut prev_block = zeroed_state();
        let mut next_block = zeroed_state();
        let mut prev_c_block = &mut prev_block as *mut ZSTD_compressedBlockState_t;
        let mut next_c_block = &mut next_block as *mut ZSTD_compressedBlockState_t;
        let state = target_block_test_state(
            &mut seq_store,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            1,
        );
        let prev_ptr = prev_c_block;
        let next_ptr = next_c_block;
        let source = [0x3cu8; 128];
        let mut output = [0xa5u8; 128];

        let result = unsafe {
            compress_block_target_c_block_size_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                ZSTD_TARGET_CBLOCK_BSS_COMPRESS,
                0,
                target_block_test_superblock_compressed,
            )
        };

        assert_eq!(result, 1);
        assert_eq!(unsafe { *state.prev_c_block }, next_ptr);
        assert_eq!(unsafe { *state.next_c_block }, prev_ptr);
        assert_eq!(output, [0xa5u8; 128]);
    }

    #[test]
    fn frame_progress_unknown_pledge_updates_counters() {
        let mut consumed = 7;
        let mut produced = 11;
        let result =
            unsafe { ZSTD_rust_updateFrameProgression(&mut consumed, &mut produced, 0, 5, 13, 2) };

        assert_eq!(result, 0);
        assert_eq!(consumed, 12);
        assert_eq!(produced, 26);
    }

    #[test]
    fn frame_progress_exact_pledge_is_accepted() {
        let mut consumed = 7;
        let mut produced = 11;
        let result =
            unsafe { ZSTD_rust_updateFrameProgression(&mut consumed, &mut produced, 13, 5, 13, 2) };

        assert_eq!(result, 0);
        assert_eq!(consumed, 12);
        assert_eq!(produced, 26);
    }

    #[test]
    fn frame_progress_one_byte_overrun_is_reported() {
        let mut consumed = 7;
        let mut produced = 11;
        let result =
            unsafe { ZSTD_rust_updateFrameProgression(&mut consumed, &mut produced, 13, 6, 13, 2) };

        assert_eq!(result, 1);
        assert_eq!(consumed, 13);
    }

    #[test]
    fn frame_progress_counters_update_before_overrun_result() {
        let mut consumed = 100;
        let mut produced = 200;
        let result = unsafe {
            ZSTD_rust_updateFrameProgression(&mut consumed, &mut produced, 106, 7, 17, 3)
        };

        assert_eq!(result, 1);
        assert_eq!(consumed, 107);
        assert_eq!(produced, 220);
    }

    #[test]
    fn frame_progression_constructs_single_thread_values() {
        let consumed = 11_u64;
        let buffered = 37_usize;
        let produced = 53_u64;
        let expected = ZSTD_frameProgression {
            ingested: consumed + buffered as u64,
            consumed,
            produced,
            flushed: produced,
            currentJobID: 0,
            nbActiveWorkers: 0,
        };

        assert_eq!(frame_progression(consumed, buffered, produced), expected);
        assert_eq!(
            ZSTD_rust_frameProgression(consumed, buffered, produced),
            expected
        );
    }

    #[test]
    fn frame_progression_wraps_buffered_input_to_u64() {
        let consumed = u64::MAX - 3;
        let buffered = 8_usize;
        let progression = ZSTD_rust_frameProgression(consumed, buffered, 17);

        assert_eq!(progression.ingested, consumed.wrapping_add(buffered as u64));
        assert_eq!(progression.consumed, consumed);
        assert_eq!(progression.produced, 17);
        assert_eq!(progression.flushed, 17);
        assert_eq!(progression.currentJobID, 0);
        assert_eq!(progression.nbActiveWorkers, 0);
    }

    unsafe extern "C" fn to_flush_now_test_callback(context: *mut c_void) -> usize {
        let calls = unsafe { &mut *context.cast::<usize>() };
        *calls += 1;
        17
    }

    #[test]
    fn to_flush_now_only_calls_mt_callback_for_workers() {
        let mut calls: usize = 0;
        let mut state = ZSTD_rust_toFlushNowState {
            callback_context: &mut calls as *mut usize as *mut c_void,
            nb_workers: 0,
            to_flush_now: to_flush_now_test_callback,
        };

        assert_eq!(unsafe { ZSTD_rust_toFlushNow(&state) }, 0);
        assert_eq!(calls, 0);

        state.nb_workers = 1;
        assert_eq!(unsafe { ZSTD_rust_toFlushNow(&state) }, 17);
        assert_eq!(calls, 1);
    }

    #[test]
    fn to_flush_now_rejects_a_null_state() {
        assert_eq!(
            unsafe { ZSTD_rust_toFlushNow(ptr::null()) },
            ERROR(ZstdErrorCode::Generic)
        );
    }

    #[test]
    fn next_input_size_hint_uses_remaining_stable_block_capacity() {
        let hint = ZSTD_rust_nextInputSizeHint(ZSTD_BM_STABLE, 256, 37, 99, 12);

        assert_eq!(next_input_size_hint(ZSTD_BM_STABLE, 256, 37, 99, 12), 219);
        assert_eq!(hint, 219);
    }

    #[test]
    fn next_input_size_hint_replaces_empty_buffered_hint_with_block_size() {
        assert_eq!(
            ZSTD_rust_nextInputSizeHint(ZSTD_BM_BUFFERED, 256, 37, 128, 128),
            256
        );
    }

    #[test]
    fn next_input_size_hint_returns_nonzero_buffered_hint() {
        assert_eq!(
            ZSTD_rust_nextInputSizeHint(ZSTD_BM_BUFFERED, 256, 37, 128, 32),
            96
        );
    }

    unsafe extern "C" fn next_input_size_hint_mt_or_st_test_callback(
        context: *mut c_void,
    ) -> usize {
        let calls = unsafe { &mut *context.cast::<usize>() };
        *calls += 1;
        777
    }

    fn next_input_size_hint_mt_or_st_test_state(
        nb_workers: c_int,
        calls: &mut usize,
    ) -> ZSTD_rust_nextInputSizeHintMTorSTState {
        ZSTD_rust_nextInputSizeHintMTorSTState {
            block_size_max: 256,
            stable_in_not_consumed: 37,
            in_buff_target: 128,
            in_buff_pos: 32,
            nb_workers,
            in_buffer_mode: ZSTD_BM_BUFFERED,
            mt_context: calls as *mut usize as *mut c_void,
            mt_next_input_size_hint: Some(next_input_size_hint_mt_or_st_test_callback),
        }
    }

    #[test]
    fn next_input_size_hint_mt_or_st_dispatches_to_mt_callback_for_workers() {
        let mut calls = 0;
        let state = next_input_size_hint_mt_or_st_test_state(1, &mut calls);

        assert_eq!(unsafe { ZSTD_rust_nextInputSizeHintMTorST(&state) }, 777);
        assert_eq!(calls, 1);
    }

    #[test]
    fn next_input_size_hint_mt_or_st_uses_single_thread_leaf_without_workers() {
        let mut calls = 0;
        let state = next_input_size_hint_mt_or_st_test_state(0, &mut calls);

        assert_eq!(unsafe { ZSTD_rust_nextInputSizeHintMTorST(&state) }, 96);
        assert_eq!(calls, 0);
    }

    #[test]
    fn mt_next_input_size_hint_handles_empty_input_buffer() {
        assert_eq!(mt_next_input_size_hint(128, 0), 128);
        assert_eq!(ZSTDMT_rust_nextInputSizeHint(128, 0), 128);
    }

    #[test]
    fn mt_next_input_size_hint_returns_remaining_capacity() {
        assert_eq!(mt_next_input_size_hint(128, 37), 91);
        assert_eq!(ZSTDMT_rust_nextInputSizeHint(128, 37), 91);
    }

    #[test]
    fn mt_next_input_size_hint_replaces_full_buffer_with_target_size() {
        assert_eq!(ZSTDMT_rust_nextInputSizeHint(128, 128), 128);
    }

    #[test]
    fn mt_next_input_size_hint_preserves_zero_target_behavior() {
        assert_eq!(ZSTDMT_rust_nextInputSizeHint(0, 0), 0);
    }

    #[test]
    fn mt_next_input_size_hint_preserves_wrapped_overfill() {
        assert_eq!(ZSTDMT_rust_nextInputSizeHint(3, 4), usize::MAX);
    }

    #[test]
    fn mt_sizeof_cctx_handles_zero_components() {
        assert_eq!(mt_sizeof_cctx(0, 0, 0, 0, 0, 0, 0, 0), 0);
        assert_eq!(ZSTDMT_rust_sizeofCCtx(0, 0, 0, 0, 0, 0, 0, 0), 0);
    }

    #[test]
    fn mt_sizeof_cctx_adds_all_components_in_order() {
        assert_eq!(mt_sizeof_cctx(1, 2, 3, 4, 5, 6, 7, 8), 36);
        assert_eq!(ZSTDMT_rust_sizeofCCtx(1, 2, 3, 4, 5, 6, 7, 8), 36);
    }

    #[test]
    fn mt_sizeof_cctx_wraps_like_c_size_t_addition() {
        assert_eq!(mt_sizeof_cctx(usize::MAX, 1, 2, 3, 4, 5, 6, 7), 27);
        assert_eq!(ZSTDMT_rust_sizeofCCtx(usize::MAX, 1, 2, 3, 4, 5, 6, 7), 27);
    }

    #[test]
    fn in_buffer_for_end_flush_returns_stable_expected_buffer() {
        let expected_src = b"input".as_ptr().cast::<c_void>();
        let result = ZSTD_rust_inBufferForEndFlush(ZSTD_BM_STABLE, expected_src, 37, 11);

        assert_eq!(result.src, expected_src);
        assert_eq!(result.size, 37);
        assert_eq!(result.pos, 11);

        let null_result = ZSTD_rust_inBufferForEndFlush(ZSTD_BM_STABLE, ptr::null(), 37, 11);

        assert!(null_result.src.is_null());
        assert_eq!(null_result.size, 37);
        assert_eq!(null_result.pos, 11);
    }

    #[test]
    fn in_buffer_for_end_flush_clears_buffered_and_other_modes() {
        let expected_src = b"input".as_ptr().cast::<c_void>();

        for mode in [ZSTD_BM_BUFFERED, 42] {
            let result = ZSTD_rust_inBufferForEndFlush(mode, expected_src, 37, 11);

            assert!(result.src.is_null());
            assert_eq!(result.size, 0);
            assert_eq!(result.pos, 0);
        }
    }

    #[test]
    fn end_stream_remaining_ignores_estimate_components_after_frame_end() {
        assert_eq!(end_stream_remaining(17, 1, 1), 17);
        assert_eq!(ZSTD_rust_endStreamRemaining(17, 1, 1), 17);
    }

    #[test]
    fn end_stream_remaining_adds_block_header_without_checksum() {
        assert_eq!(end_stream_remaining(17, 0, 0), 20);
        assert_eq!(ZSTD_rust_endStreamRemaining(17, 0, 0), 20);
    }

    #[test]
    fn end_stream_remaining_adds_block_header_and_checksum() {
        assert_eq!(end_stream_remaining(17, 0, 1), 24);
        assert_eq!(ZSTD_rust_endStreamRemaining(17, 0, 1), 24);
    }

    #[test]
    fn end_stream_remaining_wraps_size_t_additions() {
        assert_eq!(end_stream_remaining(usize::MAX, 0, 1), 6);
        assert_eq!(ZSTD_rust_endStreamRemaining(usize::MAX, 0, 1), 6);
    }

    #[test]
    fn check_buffer_stability_accepts_matching_stable_input() {
        let expected_src = b"input".as_ptr().cast::<c_void>();

        assert_eq!(
            check_buffer_stability(
                ZSTD_BM_STABLE,
                ZSTD_BM_BUFFERED,
                expected_src,
                11,
                expected_src,
                11,
                0,
                37,
                5,
            ),
            0
        );
        assert_eq!(
            ZSTD_rust_checkBufferStability(
                ZSTD_BM_STABLE,
                ZSTD_BM_BUFFERED,
                expected_src,
                11,
                expected_src,
                11,
                0,
                37,
                5,
            ),
            0
        );
    }

    #[test]
    fn check_buffer_stability_rejects_changed_input_pointer_or_position() {
        let expected_src = b"input".as_ptr().cast::<c_void>();
        let other_src = b"other".as_ptr().cast::<c_void>();
        let error = ERROR(ZstdErrorCode::StabilityConditionNotRespected);

        assert_eq!(
            ZSTD_rust_checkBufferStability(
                ZSTD_BM_STABLE,
                ZSTD_BM_BUFFERED,
                expected_src,
                11,
                other_src,
                11,
                0,
                37,
                5,
            ),
            error
        );
        assert_eq!(
            ZSTD_rust_checkBufferStability(
                ZSTD_BM_STABLE,
                ZSTD_BM_BUFFERED,
                expected_src,
                11,
                expected_src,
                12,
                0,
                37,
                5,
            ),
            error
        );
    }

    #[test]
    fn check_buffer_stability_ignores_input_changes_in_buffered_mode() {
        let expected_src = b"input".as_ptr().cast::<c_void>();
        let other_src = b"other".as_ptr().cast::<c_void>();

        assert_eq!(
            ZSTD_rust_checkBufferStability(
                ZSTD_BM_BUFFERED,
                ZSTD_BM_BUFFERED,
                expected_src,
                11,
                other_src,
                12,
                0,
                37,
                5,
            ),
            0
        );
    }

    #[test]
    fn check_buffer_stability_validates_stable_output_remainder() {
        let expected_src = b"input".as_ptr().cast::<c_void>();
        let error = ERROR(ZstdErrorCode::StabilityConditionNotRespected);

        assert_eq!(
            ZSTD_rust_checkBufferStability(
                ZSTD_BM_BUFFERED,
                ZSTD_BM_STABLE,
                expected_src,
                0,
                ptr::null(),
                0,
                32,
                40,
                8,
            ),
            0
        );
        assert_eq!(
            ZSTD_rust_checkBufferStability(
                ZSTD_BM_BUFFERED,
                ZSTD_BM_STABLE,
                expected_src,
                0,
                ptr::null(),
                0,
                32,
                40,
                7,
            ),
            error
        );
        assert_eq!(
            ZSTD_rust_checkBufferStability(
                ZSTD_BM_BUFFERED,
                ZSTD_BM_STABLE,
                expected_src,
                0,
                ptr::null(),
                0,
                usize::MAX,
                3,
                4,
            ),
            0
        );
    }

    #[test]
    fn set_buffer_expectations_updates_only_enabled_stable_modes() {
        let expected_src = b"expected".as_ptr().cast::<c_void>();
        let input_src = b"input".as_ptr().cast::<c_void>();
        let mut expected_input = ZSTD_inBuffer {
            src: expected_src,
            size: 3,
            pos: 1,
        };
        let input = ZSTD_inBuffer {
            src: input_src,
            size: 11,
            pos: 7,
        };
        let output = ZSTD_outBuffer {
            dst: ptr::null_mut(),
            size: 40,
            pos: 9,
        };
        let mut expected_output_size = 5;

        unsafe {
            ZSTD_rust_setBufferExpectations(
                ZSTD_BM_STABLE,
                ZSTD_BM_STABLE,
                &mut expected_input,
                &mut expected_output_size,
                &output,
                &input,
            );
        }

        assert_eq!(expected_input.src, input.src);
        assert_eq!(expected_input.size, input.size);
        assert_eq!(expected_input.pos, input.pos);
        assert_eq!(expected_output_size, 31);

        let original_input_src = expected_input.src;
        let original_input_size = expected_input.size;
        let original_input_pos = expected_input.pos;
        let original_output_size = expected_output_size;
        let other_input = ZSTD_inBuffer {
            src: expected_src,
            size: 99,
            pos: 22,
        };
        let other_output = ZSTD_outBuffer {
            dst: ptr::null_mut(),
            size: 3,
            pos: 8,
        };

        unsafe {
            ZSTD_rust_setBufferExpectations(
                ZSTD_BM_BUFFERED,
                ZSTD_BM_BUFFERED,
                &mut expected_input,
                &mut expected_output_size,
                &other_output,
                &other_input,
            );
        }

        assert_eq!(expected_input.src, original_input_src);
        assert_eq!(expected_input.size, original_input_size);
        assert_eq!(expected_input.pos, original_input_pos);
        assert_eq!(expected_output_size, original_output_size);
    }

    #[test]
    fn sequence_api_plan_places_input_and_frame_checksums_around_blocks() {
        assert_eq!(
            sequence_api_plan(false, ZSTD_SF_NO_BLOCK_DELIMITERS, 1, 1),
            Ok(SequenceApiPlan {
                update_input_checksum: true,
                append_frame_checksum: true,
            })
        );
    }

    #[test]
    fn sequence_api_plan_disables_checksums_for_literals_variant() {
        assert_eq!(
            sequence_api_plan(true, ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS, 0, 0),
            Ok(SequenceApiPlan {
                update_input_checksum: false,
                append_frame_checksum: false,
            })
        );
    }

    #[test]
    fn sequence_api_plan_preserves_literals_validation_precedence() {
        assert_eq!(
            ERR_getErrorCode(
                sequence_api_plan(true, ZSTD_SF_NO_BLOCK_DELIMITERS, 1, 1).unwrap_err()
            ),
            ZstdErrorCode::FrameParameterUnsupported as i32
        );
        assert_eq!(
            ERR_getErrorCode(
                sequence_api_plan(true, ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS, 1, 1).unwrap_err()
            ),
            ZstdErrorCode::ParameterUnsupported as i32
        );
        assert_eq!(
            ERR_getErrorCode(
                sequence_api_plan(true, ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS, 0, 1).unwrap_err()
            ),
            ZstdErrorCode::FrameParameterUnsupported as i32
        );
    }

    #[test]
    fn sequence_api_literal_capacity_check_precedes_initialization() {
        assert_eq!(
            sequence_api_validate_literal_capacity(9, 8),
            ERROR(ZstdErrorCode::WorkSpaceTooSmall)
        );
        assert_eq!(sequence_api_validate_literal_capacity(8, 9), 0);
    }

    #[test]
    fn sequence_copier_selector_returns_no_delimiters_mode() {
        assert_eq!(
            select_sequence_copier(ZSTD_SF_NO_BLOCK_DELIMITERS),
            ZSTD_SF_NO_BLOCK_DELIMITERS
        );
        assert_eq!(
            ZSTD_rust_selectSequenceCopier(ZSTD_SF_NO_BLOCK_DELIMITERS),
            ZSTD_SF_NO_BLOCK_DELIMITERS
        );
    }

    #[test]
    fn sequence_copier_selector_returns_explicit_delimiters_mode() {
        assert_eq!(
            select_sequence_copier(ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS),
            ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS
        );
        assert_eq!(
            ZSTD_rust_selectSequenceCopier(ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS),
            ZSTD_SF_EXPLICIT_BLOCK_DELIMITERS
        );
    }

    #[cfg(debug_assertions)]
    #[test]
    #[should_panic]
    fn sequence_copier_selector_rejects_invalid_mode_in_debug() {
        let _ = select_sequence_copier(-1);
    }

    #[cfg(debug_assertions)]
    #[test]
    #[should_panic]
    fn sequence_copier_selector_rejects_unsupported_mode_in_debug() {
        let _ = select_sequence_copier(2);
    }

    #[cfg(not(debug_assertions))]
    #[test]
    fn sequence_copier_selector_falls_back_to_no_delimiters_in_release() {
        assert_eq!(
            ZSTD_rust_selectSequenceCopier(-1),
            ZSTD_SF_NO_BLOCK_DELIMITERS
        );
        assert_eq!(
            ZSTD_rust_selectSequenceCopier(2),
            ZSTD_SF_NO_BLOCK_DELIMITERS
        );
    }

    #[test]
    fn sequence_block_action_keeps_first_block_from_using_rle() {
        assert_eq!(
            sequence_block_action(1, 1, 1, 2),
            SequenceBlockAction::Compressed
        );
        assert_eq!(sequence_block_action(0, 1, 1, 2), SequenceBlockAction::Rle);
    }

    #[test]
    fn sequence_block_action_maps_entropy_fallbacks() {
        assert_eq!(sequence_block_action(0, 0, 0, 0), SequenceBlockAction::Raw);
        assert_eq!(sequence_block_action(0, 0, 0, 1), SequenceBlockAction::Rle);
        assert_eq!(
            sequence_block_action(0, 0, 0, 2),
            SequenceBlockAction::Compressed
        );
    }

    #[allow(clippy::too_many_arguments)]
    unsafe extern "C" fn single_block_test_entropy_compress(
        _seq_store: *const SeqStore_t,
        _prev_entropy: *const ZSTD_entropyCTables_t,
        _next_entropy: *mut ZSTD_entropyCTables_t,
        strategy: c_int,
        _disable_literal_compression: c_int,
        dst: *mut c_void,
        dst_capacity: usize,
        _src_size: usize,
        _workspace: *mut c_void,
        _workspace_size: usize,
        _bmi2: c_int,
    ) -> usize {
        match strategy {
            0 => 0,
            1 => {
                assert!(dst_capacity >= 2);
                unsafe {
                    *dst.cast::<u8>() = 0x11;
                    *dst.cast::<u8>().add(1) = 0x22;
                }
                2
            }
            _ => ERROR(ZstdErrorCode::Generic),
        }
    }

    fn single_block_test_state(
        seq_store: &SeqStore_t,
        d_rep: &mut [u32; ZSTD_REP_NUM],
        c_rep: &mut [u32; ZSTD_REP_NUM],
        prev_block: &mut ZSTD_compressedBlockState_t,
        next_block: &mut ZSTD_compressedBlockState_t,
        prev_c_block: &mut *mut ZSTD_compressedBlockState_t,
        next_c_block: &mut *mut ZSTD_compressedBlockState_t,
        seq_collector: &mut SeqCollector,
        strategy: c_int,
        is_first_block: c_int,
    ) -> ZSTD_rust_seqStoreSingleBlockState {
        *prev_c_block = prev_block;
        *next_c_block = next_block;
        ZSTD_rust_seqStoreSingleBlockState {
            seq_store,
            d_rep: d_rep.as_mut_ptr(),
            c_rep: c_rep.as_mut_ptr(),
            prev_c_block,
            next_c_block,
            tmp_workspace: ptr::null_mut(),
            tmp_wksp_size: 0,
            seq_collector,
            strategy,
            disable_literal_compression: 0,
            bmi2: 0,
            is_first_block,
        }
    }

    fn single_block_test_seams() -> SingleBlockSeams {
        SingleBlockSeams {
            entropy_compress: single_block_test_entropy_compress,
            ..SingleBlockSeams::production()
        }
    }

    fn block_internal_test_state(
        seq_store: &mut SeqStore_t,
        prev_block: &mut ZSTD_compressedBlockState_t,
        next_block: &mut ZSTD_compressedBlockState_t,
        prev_c_block: &mut *mut ZSTD_compressedBlockState_t,
        next_c_block: &mut *mut ZSTD_compressedBlockState_t,
        seq_collector: &mut SeqCollector,
        strategy: c_int,
        is_first_block: c_int,
    ) -> ZSTD_rust_blockInternalState {
        *prev_c_block = prev_block;
        *next_c_block = next_block;
        ZSTD_rust_blockInternalState {
            seq_store,
            prev_c_block,
            next_c_block,
            tmp_workspace: ptr::null_mut(),
            tmp_wksp_size: 0,
            seq_collector,
            strategy,
            disable_literal_compression: 0,
            bmi2: 0,
            is_first_block,
        }
    }

    struct SplitBlockTestStore {
        seq_store: SeqStore_t,
        _sequences: Box<[SeqDef; 2]>,
        _ll_code: Box<[u8; 2]>,
        _ml_code: Box<[u8; 2]>,
        _of_code: Box<[u8; 2]>,
        _literals: Box<[u8; 6]>,
    }

    fn split_block_test_seq_store() -> SplitBlockTestStore {
        let mut sequences = Box::new([
            SeqDef {
                offBase: 4,
                litLength: 2,
                mlBase: 0,
            },
            SeqDef {
                offBase: 5,
                litLength: 2,
                mlBase: 0,
            },
        ]);
        let mut ll_code = Box::new([1u8; 2]);
        let mut ml_code = Box::new([1u8; 2]);
        let mut of_code = Box::new([1u8; 2]);
        let mut literals = Box::new([0u8; 6]);
        let sequences_start = sequences.as_mut_ptr();
        let literals_start = literals.as_mut_ptr();
        let seq_store = SeqStore_t {
            sequencesStart: sequences_start,
            sequences: unsafe { sequences_start.add(sequences.len()) },
            litStart: literals_start,
            lit: unsafe { literals_start.add(literals.len()) },
            llCode: ll_code.as_mut_ptr(),
            mlCode: ml_code.as_mut_ptr(),
            ofCode: of_code.as_mut_ptr(),
            maxNbSeq: sequences.len(),
            maxNbLit: literals.len(),
            longLengthType: 0,
            longLengthPos: 0,
        };
        SplitBlockTestStore {
            seq_store,
            _sequences: sequences,
            _ll_code: ll_code,
            _ml_code: ml_code,
            _of_code: of_code,
            _literals: literals,
        }
    }

    #[allow(clippy::too_many_arguments)]
    fn split_block_test_state(
        seq_store: &SeqStore_t,
        partitions: &[u32],
        next_seq_store: &mut SeqStore_t,
        curr_seq_store: &mut SeqStore_t,
        prev_block: &mut ZSTD_compressedBlockState_t,
        next_block: &mut ZSTD_compressedBlockState_t,
        prev_c_block: &mut *mut ZSTD_compressedBlockState_t,
        next_c_block: &mut *mut ZSTD_compressedBlockState_t,
        seq_collector: &mut SeqCollector,
    ) -> ZSTD_rust_splitBlockState {
        *prev_c_block = prev_block;
        *next_c_block = next_block;
        ZSTD_rust_splitBlockState {
            seq_store,
            partitions: partitions.as_ptr(),
            next_seq_store,
            curr_seq_store,
            prev_c_block,
            next_c_block,
            tmp_workspace: ptr::null_mut(),
            tmp_wksp_size: 0,
            seq_collector,
            block_size_max: ZSTD_BLOCKSIZE_MAX,
            strategy: 0,
            disable_literal_compression: 0,
            bmi2: 0,
            is_first_block: 1,
        }
    }

    #[test]
    fn split_block_body_emits_partitions_and_final_literals() {
        let fixture = split_block_test_seq_store();
        let partitions = [1, 2];
        let mut next_seq_store = unsafe { MaybeUninit::<SeqStore_t>::zeroed().assume_init() };
        let mut curr_seq_store = unsafe { MaybeUninit::<SeqStore_t>::zeroed().assume_init() };
        let mut prev_block = zeroed_state();
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let mut seq_collector = SeqCollector {
            collectSequences: 0,
            seqStart: ptr::null_mut(),
            seqIndex: 0,
            maxSequences: 0,
        };
        let state = split_block_test_state(
            &fixture.seq_store,
            &partitions,
            &mut next_seq_store,
            &mut curr_seq_store,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            &mut seq_collector,
        );
        let source: Vec<u8> = (0..12).collect();
        let mut output = [0xa5u8; 32];

        let result = unsafe {
            compress_block_split_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
                1,
                single_block_test_seams(),
            )
        };

        assert_eq!(result, 18);
        assert_eq!(&output[ZSTD_BLOCK_HEADER_SIZE..8], &source[..5]);
        assert_eq!(&output[8 + ZSTD_BLOCK_HEADER_SIZE..result], &source[5..]);
        assert!(std::ptr::eq(prev_c_block, &prev_block));
    }

    #[test]
    fn block_internal_body_collects_sequences_before_entropy_emission() {
        let (mut seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut prev_block = zeroed_state();
        prev_block.entropy.fse.offcode_repeatMode = 2;
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let mut output_sequences = [ZSTD_Sequence {
            offset: 0xa5,
            litLength: 0xa5,
            matchLength: 0xa5,
            rep: 0xa5,
        }];
        let mut seq_collector = SeqCollector {
            collectSequences: 1,
            seqStart: output_sequences.as_mut_ptr(),
            seqIndex: 0,
            maxSequences: output_sequences.len(),
        };
        let state = block_internal_test_state(
            &mut seq_store,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            &mut seq_collector,
            1,
            0,
        );
        let source = [0x5au8; 16];
        let mut output = [0xa5u8; 16];

        let result = unsafe {
            compress_block_internal_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
                single_block_test_seams(),
            )
        };

        assert_eq!(result, 0);
        assert_eq!(seq_collector.seqIndex, 1);
        assert_eq!(output_sequences[0].litLength, 0);
        assert!(std::ptr::eq(prev_c_block, &next_block));
        assert!(std::ptr::eq(next_c_block, &prev_block));
        assert_eq!(prev_block.entropy.fse.offcode_repeatMode, 2);
    }

    #[test]
    fn block_internal_body_gates_rle_and_cleans_repeat_mode() {
        let (mut seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut prev_block = zeroed_state();
        prev_block.entropy.fse.offcode_repeatMode = 2;
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let mut seq_collector = SeqCollector {
            collectSequences: 0,
            seqStart: ptr::null_mut(),
            seqIndex: 0,
            maxSequences: 0,
        };
        let state = block_internal_test_state(
            &mut seq_store,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            &mut seq_collector,
            1,
            0,
        );
        let source = [0x5au8; 16];
        let mut output = [0xa5u8; 32];

        let result = unsafe {
            compress_block_internal_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
                single_block_test_seams(),
            )
        };

        assert_eq!(result, 1);
        assert_eq!(output[0], source[0]);
        assert_eq!(prev_block.entropy.fse.offcode_repeatMode, 1);
    }

    #[test]
    fn block_internal_body_propagates_entropy_error_through_repeat_cleanup() {
        let (mut seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut prev_block = zeroed_state();
        prev_block.entropy.fse.offcode_repeatMode = 2;
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let mut seq_collector = SeqCollector {
            collectSequences: 0,
            seqStart: ptr::null_mut(),
            seqIndex: 0,
            maxSequences: 0,
        };
        let state = block_internal_test_state(
            &mut seq_store,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            &mut seq_collector,
            -1,
            0,
        );
        let source = [0x5au8; 16];
        let mut output = [0xa5u8; 32];

        let result = unsafe {
            compress_block_internal_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
                single_block_test_seams(),
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::Generic));
        assert_eq!(output, [0xa5u8; 32]);
        assert_eq!(prev_block.entropy.fse.offcode_repeatMode, 1);
    }

    #[test]
    fn single_block_body_propagates_entropy_errors_without_serializing() {
        let (seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut d_rep = [1, 4, 8];
        let mut c_rep = d_rep;
        let mut prev_block = zeroed_state();
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let mut seq_collector = SeqCollector {
            collectSequences: 0,
            seqStart: ptr::null_mut(),
            seqIndex: 0,
            maxSequences: 0,
        };
        let state = single_block_test_state(
            &seq_store,
            &mut d_rep,
            &mut c_rep,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            &mut seq_collector,
            -1,
            1,
        );
        let source = *b"entropy error";
        let mut output = [0xa5u8; 32];

        let result = unsafe {
            compress_seq_store_single_block_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
                0,
                single_block_test_seams(),
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::Generic));
        assert_eq!(output, [0xa5u8; 32]);
        assert_eq!(d_rep, [1, 4, 8]);
        assert_eq!(c_rep, [1, 4, 8]);
    }

    #[test]
    fn single_block_body_serializes_raw_entropy_fallback() {
        let (seq_store, _sequences, _literals) = target_block_test_seq_store();
        let mut d_rep = [1, 4, 8];
        let mut c_rep = d_rep;
        let mut prev_block = zeroed_state();
        let mut next_block = zeroed_state();
        let mut prev_c_block = ptr::null_mut();
        let mut next_c_block = ptr::null_mut();
        let mut seq_collector = SeqCollector {
            collectSequences: 0,
            seqStart: ptr::null_mut(),
            seqIndex: 0,
            maxSequences: 0,
        };
        let state = single_block_test_state(
            &seq_store,
            &mut d_rep,
            &mut c_rep,
            &mut prev_block,
            &mut next_block,
            &mut prev_c_block,
            &mut next_c_block,
            &mut seq_collector,
            0,
            1,
        );
        let source = *b"raw fallback";
        let mut output = [0xa5u8; 32];

        let result = unsafe {
            compress_seq_store_single_block_body_with(
                &state,
                output.as_mut_ptr().cast(),
                output.len(),
                source.as_ptr().cast(),
                source.len(),
                1,
                0,
                single_block_test_seams(),
            )
        };

        assert_eq!(result, source.len() + ZSTD_BLOCK_HEADER_SIZE);
        assert_eq!(&output[ZSTD_BLOCK_HEADER_SIZE..result], &source);
    }

    #[test]
    fn single_block_body_gates_rle_on_first_block_and_confirms_compressed_state() {
        for is_first_block in [0, 1] {
            let (seq_store, _sequences, _literals) = target_block_test_seq_store();
            let mut d_rep = [1, 4, 8];
            let mut c_rep = d_rep;
            let mut prev_block = zeroed_state();
            let mut next_block = zeroed_state();
            next_block.entropy.fse.offcode_repeatMode = 2;
            let mut prev_c_block = ptr::null_mut();
            let mut next_c_block = ptr::null_mut();
            let mut seq_collector = SeqCollector {
                collectSequences: 0,
                seqStart: ptr::null_mut(),
                seqIndex: 0,
                maxSequences: 0,
            };
            let state = single_block_test_state(
                &seq_store,
                &mut d_rep,
                &mut c_rep,
                &mut prev_block,
                &mut next_block,
                &mut prev_c_block,
                &mut next_c_block,
                &mut seq_collector,
                1,
                is_first_block,
            );
            let source = [0x5au8; 16];
            let mut output = [0xa5u8; 32];

            let result = unsafe {
                compress_seq_store_single_block_body_with(
                    &state,
                    output.as_mut_ptr().cast(),
                    output.len(),
                    source.as_ptr().cast(),
                    source.len(),
                    1,
                    0,
                    single_block_test_seams(),
                )
            };

            if is_first_block == 0 {
                assert_eq!(result, 4);
                assert_eq!(output[3], source[0]);
                assert!(std::ptr::eq(prev_c_block, &prev_block));
            } else {
                assert_eq!(result, ZSTD_BLOCK_HEADER_SIZE + 2);
                assert_eq!(&output[ZSTD_BLOCK_HEADER_SIZE..result], &[0x11, 0x22]);
                assert!(std::ptr::eq(prev_c_block, &next_block));
                assert!(std::ptr::eq(next_c_block, &prev_block));
            }
            let expected_repeat_mode = if is_first_block == 0 { 0 } else { 1 };
            assert_eq!(
                unsafe { (*prev_c_block).entropy.fse.offcode_repeatMode },
                expected_repeat_mode
            );
        }
    }

    #[test]
    fn empty_sequence_block_preserves_header_and_capacity_contract() {
        let mut output = [0xa5; 4];
        assert_eq!(
            unsafe { write_empty_sequence_block(output.as_mut_ptr(), output.len()) },
            ZSTD_BLOCK_HEADER_SIZE
        );
        assert_eq!(output, [1, 0, 0, 0]);

        let mut short_output = [0xa5; 3];
        assert_eq!(
            unsafe { write_empty_sequence_block(short_output.as_mut_ptr(), short_output.len()) },
            ERROR(ZstdErrorCode::DstSizeTooSmall)
        );
        assert_eq!(short_output, [0xa5; 3]);
    }

    #[test]
    fn empty_sequence_literals_block_writes_only_the_three_byte_header() {
        let mut output = [0xa5; 4];
        assert_eq!(
            unsafe { write_empty_sequence_literals_block(output.as_mut_ptr(), output.len()) },
            ZSTD_BLOCK_HEADER_SIZE
        );
        assert_eq!(output, [1, 0, 0, 0xa5]);

        let mut short_output = [0xa5; 2];
        assert_eq!(
            unsafe {
                write_empty_sequence_literals_block(short_output.as_mut_ptr(), short_output.len())
            },
            ERROR(ZstdErrorCode::DstSizeTooSmall)
        );
        assert_eq!(short_output, [0xa5; 2]);
    }

    #[test]
    fn invalidate_rep_codes_clears_all_entries() {
        let mut rep = [11u32, 22, 33];

        unsafe { ZSTD_rust_invalidateRepCodes(rep.as_mut_ptr()) };

        assert_eq!(rep, [0; ZSTD_REP_NUM]);
    }

    #[test]
    fn window_clear_writes_the_same_end_to_both_limits() {
        let mut low_limit = 11u32;
        let mut dict_limit = 22u32;

        unsafe { ZSTD_rust_windowClear(0x1234_5678, &mut low_limit, &mut dict_limit) };

        assert_eq!(low_limit, 0x1234_5678);
        assert_eq!(dict_limit, 0x1234_5678);
    }

    #[cfg(target_pointer_width = "64")]
    #[test]
    fn window_clear_truncates_a_large_size_t_like_c_u32_cast() {
        let mut low_limit = 11u32;
        let mut dict_limit = 22u32;
        let end_t = 0x1_0000_0000usize + 0x89ab_cdef;

        unsafe { ZSTD_rust_windowClear(end_t, &mut low_limit, &mut dict_limit) };

        assert_eq!(low_limit, 0x89ab_cdef);
        assert_eq!(dict_limit, 0x89ab_cdef);
    }

    #[test]
    fn invalidate_match_state_clears_window_and_private_fields() {
        let mut low_limit = 11u32;
        let mut dict_limit = 22u32;
        let mut next_to_update = 33u32;
        let mut loaded_dict_end = 44u32;
        let mut lit_length_sum = 55u32;
        let marker = 0x5au8;
        let mut dict_match_state = (&marker as *const u8).cast::<c_void>();

        unsafe {
            ZSTD_rust_invalidateMatchState(
                0x1234_5678,
                &mut low_limit,
                &mut dict_limit,
                &mut next_to_update,
                &mut loaded_dict_end,
                &mut lit_length_sum,
                &mut dict_match_state,
            )
        };

        assert_eq!(low_limit, 0x1234_5678);
        assert_eq!(dict_limit, 0x1234_5678);
        assert_eq!(next_to_update, 0x1234_5678);
        assert_eq!(loaded_dict_end, 0);
        assert_eq!(lit_length_sum, 0);
        assert!(dict_match_state.is_null());
    }

    #[test]
    fn window_update_leaves_empty_input_untouched() {
        let mut state = ZSTD_rust_windowUpdateState {
            nextSrc: ptr::null(),
            base: ptr::null(),
            dictBase: ptr::null(),
            dictLimit: 2,
            lowLimit: 2,
        };
        let original = state;

        let result = unsafe { ZSTD_rust_windowUpdate(&mut state, ptr::null(), 0, 0) };

        assert_eq!(result, 1);
        assert_eq!(state, original);
    }

    #[test]
    fn window_init_sets_empty_sentinel_and_dictionary_predicates() {
        let mut state = ZSTD_rust_windowUpdateState {
            nextSrc: ptr::null(),
            base: ptr::null(),
            dictBase: ptr::null(),
            dictLimit: 0,
            lowLimit: 0,
        };

        unsafe { ZSTD_rust_windowInit(&mut state) };

        assert_eq!(state.dictLimit, ZSTD_WINDOW_START_INDEX);
        assert_eq!(state.lowLimit, ZSTD_WINDOW_START_INDEX);
        assert_eq!(state.dictBase as usize, state.base as usize);
        assert_eq!(
            (state.nextSrc as usize).wrapping_sub(state.base as usize),
            ZSTD_WINDOW_START_INDEX as usize
        );
        assert_eq!(
            ZSTD_rust_windowIsEmpty(state.nextSrc, state.base, state.dictLimit, state.lowLimit),
            1
        );
        assert_eq!(ZSTD_rust_windowHasExtDict(10, 2), 1);
        assert_eq!(ZSTD_rust_windowHasExtDict(10, 10), 0);
    }

    #[test]
    fn window_enforce_max_dist_updates_limits_and_invalidates_dictionary() {
        let state = ZSTD_rust_windowEnforceMaxDist(
            100,
            64,
            ZSTD_rust_windowDictState {
                lowLimit: 2,
                dictLimit: 10,
                loadedDictEnd: 8,
                invalidate: 0,
            },
        );

        assert_eq!(state.lowLimit, 36);
        assert_eq!(state.dictLimit, 36);
        assert_eq!(state.loadedDictEnd, 0);
        assert_eq!(state.invalidate, 1);
    }

    #[test]
    fn window_dictionary_policy_preserves_valid_state_and_detects_mismatch() {
        let state = ZSTD_rust_windowEnforceMaxDist(
            70,
            64,
            ZSTD_rust_windowDictState {
                lowLimit: 2,
                dictLimit: 10,
                loadedDictEnd: 8,
                invalidate: 1,
            },
        );

        assert_eq!(state.lowLimit, 2);
        assert_eq!(state.dictLimit, 10);
        assert_eq!(state.loadedDictEnd, 8);
        assert_eq!(state.invalidate, 0);
        assert_eq!(ZSTD_rust_windowCheckDictValidity(70, 64, 8, 8), 0);
        assert_eq!(ZSTD_rust_windowCheckDictValidity(100, 64, 8, 8), 1);
        assert_eq!(ZSTD_rust_windowCheckDictValidity(70, 64, 8, 10), 1);
    }

    #[test]
    fn window_update_preserves_contiguous_input_and_clips_overlapping_extdict() {
        let storage = [0u8; 64];
        let storage_start = storage.as_ptr() as usize;
        let base = unsafe { storage.as_ptr().add(16) };
        let next_src = unsafe { base.add(2) };
        let mut contiguous_state = ZSTD_rust_windowUpdateState {
            nextSrc: next_src.cast(),
            base: base.cast(),
            dictBase: base.cast(),
            dictLimit: 2,
            lowLimit: 2,
        };

        let contiguous =
            unsafe { ZSTD_rust_windowUpdate(&mut contiguous_state, next_src.cast(), 3, 0) };

        assert_eq!(contiguous, 1);
        assert_eq!(contiguous_state.nextSrc as usize, storage_start + 21);
        assert_eq!(contiguous_state.base as usize, storage_start + 16);
        assert_eq!(contiguous_state.dictBase as usize, storage_start + 16);
        assert_eq!(contiguous_state.dictLimit, 2);
        assert_eq!(contiguous_state.lowLimit, 2);

        let next_src = unsafe { base.add(6) };
        let mut forced_state = ZSTD_rust_windowUpdateState {
            nextSrc: next_src.cast(),
            base: base.cast(),
            dictBase: base.cast(),
            dictLimit: 5,
            lowLimit: 2,
        };

        let forced = unsafe { ZSTD_rust_windowUpdate(&mut forced_state, next_src.cast(), 3, 1) };

        assert_eq!(forced, 0);
        assert_eq!(forced_state.base as usize, storage_start + 16);
        assert_eq!(forced_state.nextSrc as usize, storage_start + 25);
        assert_eq!(forced_state.dictBase as usize, storage_start + 16);
        assert_eq!(forced_state.dictLimit, 6);
        assert_eq!(forced_state.lowLimit, 6);

        let next_src = unsafe { base.add(20) };
        let src = unsafe { base.add(4) };
        let mut non_contiguous_state = ZSTD_rust_windowUpdateState {
            nextSrc: next_src.cast(),
            base: base.cast(),
            dictBase: base.cast(),
            dictLimit: 5,
            lowLimit: 2,
        };

        let non_contiguous =
            unsafe { ZSTD_rust_windowUpdate(&mut non_contiguous_state, src.cast(), 10, 0) };

        assert_eq!(non_contiguous, 0);
        assert_eq!(non_contiguous_state.base as usize, storage_start);
        assert_eq!(non_contiguous_state.nextSrc as usize, storage_start + 30);
        assert_eq!(non_contiguous_state.dictBase as usize, storage_start + 16);
        assert_eq!(non_contiguous_state.dictLimit, 20);
        assert_eq!(non_contiguous_state.lowLimit, 14);
    }

    #[derive(Default)]
    struct ClearAllDictsTestContext {
        events: Vec<&'static str>,
    }

    unsafe fn clear_all_dicts_test_context(
        context: *mut c_void,
    ) -> &'static mut ClearAllDictsTestContext {
        unsafe { &mut *context.cast::<ClearAllDictsTestContext>() }
    }

    unsafe extern "C" fn clear_all_dicts_test_free_local_dict_buffer(context: *mut c_void) {
        unsafe { clear_all_dicts_test_context(context) }
            .events
            .push("free-local-buffer");
    }

    unsafe extern "C" fn clear_all_dicts_test_free_local_cdict(context: *mut c_void) {
        unsafe { clear_all_dicts_test_context(context) }
            .events
            .push("free-local-cdict");
    }

    unsafe extern "C" fn clear_all_dicts_test_clear_local_dict(context: *mut c_void) {
        unsafe { clear_all_dicts_test_context(context) }
            .events
            .push("clear-local");
    }

    unsafe extern "C" fn clear_all_dicts_test_clear_prefix_dict(context: *mut c_void) {
        unsafe { clear_all_dicts_test_context(context) }
            .events
            .push("clear-prefix");
    }

    unsafe extern "C" fn clear_all_dicts_test_clear_cdict(context: *mut c_void) {
        unsafe { clear_all_dicts_test_context(context) }
            .events
            .push("clear-cdict");
    }

    fn clear_all_dicts_test_state(
        context: &mut ClearAllDictsTestContext,
    ) -> ZSTD_rust_clearAllDictsState {
        ZSTD_rust_clearAllDictsState {
            callback_context: (context as *mut ClearAllDictsTestContext).cast(),
            free_local_dict_buffer: clear_all_dicts_test_free_local_dict_buffer,
            free_local_cdict: clear_all_dicts_test_free_local_cdict,
            clear_local_dict: clear_all_dicts_test_clear_local_dict,
            clear_prefix_dict: clear_all_dicts_test_clear_prefix_dict,
            clear_cdict: clear_all_dicts_test_clear_cdict,
        }
    }

    #[test]
    fn clear_all_dicts_preserves_dictionary_teardown_order() {
        let mut context = ClearAllDictsTestContext::default();
        let state = clear_all_dicts_test_state(&mut context);

        unsafe { ZSTD_rust_clearAllDicts(&state) };

        assert_eq!(
            context.events,
            [
                "free-local-buffer",
                "free-local-cdict",
                "clear-local",
                "clear-prefix",
                "clear-cdict"
            ]
        );
    }

    #[derive(Default)]
    struct ResetCCtxTestContext {
        events: Vec<&'static str>,
        rust_simple_compress2_completed: c_uint,
        stream_stage: c_int,
        pledged_src_size_plus_one: u64,
        rust_simple_compress2_max_block_size_set: c_uint,
        reset_params_result: usize,
    }

    unsafe fn reset_cctx_test_context(context: *mut c_void) -> &'static mut ResetCCtxTestContext {
        unsafe { &mut *context.cast::<ResetCCtxTestContext>() }
    }

    unsafe extern "C" fn reset_cctx_test_clear_all_dicts(context: *mut c_void) {
        unsafe { reset_cctx_test_context(context) }
            .events
            .push("clear-dicts");
    }

    unsafe extern "C" fn reset_cctx_test_reset_params(context: *mut c_void) -> usize {
        let context = unsafe { reset_cctx_test_context(context) };
        assert_eq!(context.rust_simple_compress2_max_block_size_set, 0);
        context.events.push("reset-params");
        context.reset_params_result
    }

    fn reset_cctx_test_state(context: &mut ResetCCtxTestContext) -> ZSTD_rust_resetCCtxState {
        ZSTD_rust_resetCCtxState {
            callback_context: (context as *mut ResetCCtxTestContext).cast(),
            rust_simple_compress2_completed: &mut context.rust_simple_compress2_completed,
            stream_stage: &mut context.stream_stage,
            pledged_src_size_plus_one: &mut context.pledged_src_size_plus_one,
            rust_simple_compress2_max_block_size_set: &mut context
                .rust_simple_compress2_max_block_size_set,
            clear_all_dicts: reset_cctx_test_clear_all_dicts,
            reset_params: reset_cctx_test_reset_params,
        }
    }

    #[test]
    fn reset_cctx_session_only_clears_session_state() {
        let mut context = ResetCCtxTestContext {
            rust_simple_compress2_completed: 1,
            stream_stage: ZSTD_CSTREAM_STAGE_LOAD,
            pledged_src_size_plus_one: 123,
            rust_simple_compress2_max_block_size_set: 1,
            ..ResetCCtxTestContext::default()
        };
        let state = reset_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCCtx(&state, ZSTD_RESET_SESSION_ONLY) };

        assert_eq!(result, 0);
        assert_eq!(context.rust_simple_compress2_completed, 0);
        assert_eq!(context.stream_stage, ZSTD_CSTREAM_STAGE_INIT);
        assert_eq!(context.pledged_src_size_plus_one, 0);
        assert_eq!(context.rust_simple_compress2_max_block_size_set, 1);
        assert!(context.events.is_empty());
    }

    #[test]
    fn reset_cctx_parameters_runs_callbacks_in_order_and_clears_max_block_flag() {
        let mut context = ResetCCtxTestContext {
            rust_simple_compress2_completed: 1,
            stream_stage: ZSTD_CSTREAM_STAGE_INIT,
            pledged_src_size_plus_one: 123,
            rust_simple_compress2_max_block_size_set: 1,
            ..ResetCCtxTestContext::default()
        };
        let state = reset_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCCtx(&state, ZSTD_RESET_PARAMETERS) };

        assert_eq!(result, 0);
        assert_eq!(context.rust_simple_compress2_completed, 0);
        assert_eq!(context.stream_stage, ZSTD_CSTREAM_STAGE_INIT);
        assert_eq!(context.pledged_src_size_plus_one, 123);
        assert_eq!(context.rust_simple_compress2_max_block_size_set, 0);
        assert_eq!(context.events, ["clear-dicts", "reset-params"]);
    }

    #[test]
    fn reset_cctx_session_and_parameters_resets_session_before_callbacks() {
        let mut context = ResetCCtxTestContext {
            rust_simple_compress2_completed: 1,
            stream_stage: ZSTD_CSTREAM_STAGE_LOAD,
            pledged_src_size_plus_one: 123,
            rust_simple_compress2_max_block_size_set: 1,
            ..ResetCCtxTestContext::default()
        };
        let state = reset_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCCtx(&state, ZSTD_RESET_SESSION_AND_PARAMETERS) };

        assert_eq!(result, 0);
        assert_eq!(context.rust_simple_compress2_completed, 0);
        assert_eq!(context.stream_stage, ZSTD_CSTREAM_STAGE_INIT);
        assert_eq!(context.pledged_src_size_plus_one, 0);
        assert_eq!(context.rust_simple_compress2_max_block_size_set, 0);
        assert_eq!(context.events, ["clear-dicts", "reset-params"]);
    }

    #[test]
    fn reset_cctx_parameters_rejects_non_init_stage_before_mutating_parameters() {
        let mut context = ResetCCtxTestContext {
            rust_simple_compress2_completed: 1,
            stream_stage: ZSTD_CSTREAM_STAGE_LOAD,
            pledged_src_size_plus_one: 123,
            rust_simple_compress2_max_block_size_set: 1,
            ..ResetCCtxTestContext::default()
        };
        let state = reset_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCCtx(&state, ZSTD_RESET_PARAMETERS) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.rust_simple_compress2_completed, 0);
        assert_eq!(context.stream_stage, ZSTD_CSTREAM_STAGE_LOAD);
        assert_eq!(context.pledged_src_size_plus_one, 123);
        assert_eq!(context.rust_simple_compress2_max_block_size_set, 1);
        assert!(context.events.is_empty());
    }

    #[test]
    fn reset_cctx_propagates_parameter_reset_error_after_clearing_state() {
        let mut context = ResetCCtxTestContext {
            rust_simple_compress2_completed: 1,
            stream_stage: ZSTD_CSTREAM_STAGE_INIT,
            pledged_src_size_plus_one: 123,
            rust_simple_compress2_max_block_size_set: 1,
            reset_params_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..ResetCCtxTestContext::default()
        };
        let state = reset_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCCtx(&state, ZSTD_RESET_PARAMETERS) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.rust_simple_compress2_completed, 0);
        assert_eq!(context.rust_simple_compress2_max_block_size_set, 0);
        assert_eq!(context.events, ["clear-dicts", "reset-params"]);
    }

    #[test]
    fn reset_cctx_ignores_unknown_directives_after_clearing_completion() {
        let mut context = ResetCCtxTestContext {
            rust_simple_compress2_completed: 1,
            stream_stage: ZSTD_CSTREAM_STAGE_LOAD,
            pledged_src_size_plus_one: 123,
            rust_simple_compress2_max_block_size_set: 1,
            ..ResetCCtxTestContext::default()
        };
        let state = reset_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCCtx(&state, 99) };

        assert_eq!(result, 0);
        assert_eq!(context.rust_simple_compress2_completed, 0);
        assert_eq!(context.stream_stage, ZSTD_CSTREAM_STAGE_LOAD);
        assert_eq!(context.pledged_src_size_plus_one, 123);
        assert_eq!(context.rust_simple_compress2_max_block_size_set, 1);
        assert!(context.events.is_empty());
    }

    #[derive(Default)]
    struct CopyCCtxTestContext {
        events: Vec<&'static str>,
        src_cctx: *const c_void,
        frame_params: ZSTD_frameParameters,
        pledged_src_size: u64,
        zbuff: c_int,
        result: usize,
    }

    unsafe extern "C" fn copy_cctx_test_internal(
        context: *mut c_void,
        src_cctx: *const c_void,
        f_params: *const ZSTD_frameParameters,
        pledged_src_size: u64,
        zbuff: c_int,
    ) -> usize {
        let context = unsafe { &mut *context.cast::<CopyCCtxTestContext>() };
        context.events.push("copy");
        context.src_cctx = src_cctx;
        context.frame_params = unsafe { *f_params };
        context.pledged_src_size = pledged_src_size;
        context.zbuff = zbuff;
        context.result
    }

    fn copy_cctx_test_state(
        context: &mut CopyCCtxTestContext,
        src_cctx: *const c_void,
        f_params: &ZSTD_frameParameters,
        pledged_src_size: &u64,
        zbuff: &c_int,
    ) -> ZSTD_rust_copyCCtxState {
        ZSTD_rust_copyCCtxState {
            callback_context: (context as *mut CopyCCtxTestContext).cast(),
            src_cctx,
            f_params,
            pledged_src_size,
            zbuff,
            copy_internal: Some(copy_cctx_test_internal),
        }
    }

    #[test]
    fn copy_cctx_converts_zero_pledge_to_unknown_and_clears_content_flag() {
        let mut context = CopyCCtxTestContext::default();
        let f_params = ZSTD_frameParameters {
            contentSizeFlag: 1,
            checksumFlag: 1,
            noDictIDFlag: 1,
        };
        let pledged_src_size = 0;
        let zbuff = 1;
        let src_cctx = 0x4000usize as *const c_void;
        let state =
            copy_cctx_test_state(&mut context, src_cctx, &f_params, &pledged_src_size, &zbuff);

        let result = unsafe { ZSTD_rust_copyCCtx(&state) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["copy"]);
        assert_eq!(context.src_cctx, src_cctx);
        assert_eq!(context.pledged_src_size, ZSTD_CONTENTSIZE_UNKNOWN);
        assert_eq!(context.zbuff, zbuff);
        assert_eq!(context.frame_params.contentSizeFlag, 0);
        assert_eq!(context.frame_params.checksumFlag, 1);
        assert_eq!(context.frame_params.noDictIDFlag, 1);
    }

    #[test]
    fn copy_cctx_forwards_nonzero_pledge_and_propagates_internal_error() {
        let mut context = CopyCCtxTestContext {
            result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..CopyCCtxTestContext::default()
        };
        let f_params = ZSTD_frameParameters {
            contentSizeFlag: 0,
            checksumFlag: 1,
            noDictIDFlag: 1,
        };
        let pledged_src_size = 123;
        let zbuff = 7;
        let state = copy_cctx_test_state(
            &mut context,
            0x4000usize as *const c_void,
            &f_params,
            &pledged_src_size,
            &zbuff,
        );

        let result = unsafe { ZSTD_rust_copyCCtx(&state) };

        assert_eq!(result, context.result);
        assert_eq!(context.events, ["copy"]);
        assert_eq!(context.pledged_src_size, pledged_src_size);
        assert_eq!(context.frame_params.contentSizeFlag, 1);
        assert_eq!(context.frame_params.checksumFlag, 1);
        assert_eq!(context.frame_params.noDictIDFlag, 1);
    }

    #[derive(Default)]
    struct CopyCCtxInternalTestContext {
        events: Vec<&'static str>,
        reset_result: usize,
        frame_params: ZSTD_frameParameters,
        pledged_src_size: u64,
        zbuff: c_int,
    }

    unsafe fn copy_cctx_internal_test_context(
        context: *mut c_void,
    ) -> &'static mut CopyCCtxInternalTestContext {
        unsafe { &mut *context.cast::<CopyCCtxInternalTestContext>() }
    }

    unsafe extern "C" fn copy_cctx_internal_test_reset(
        context: *mut c_void,
        _src_cctx: *const c_void,
        f_params: *const ZSTD_frameParameters,
        pledged_src_size: u64,
        zbuff: c_int,
    ) -> usize {
        let context = unsafe { copy_cctx_internal_test_context(context) };
        context.events.push("reset");
        context.frame_params = unsafe { *f_params };
        context.pledged_src_size = pledged_src_size;
        context.zbuff = zbuff;
        context.reset_result
    }

    unsafe extern "C" fn copy_cctx_internal_test_mark_tables_dirty(context: *mut c_void) {
        unsafe { copy_cctx_internal_test_context(context) }
            .events
            .push("dirty");
    }

    unsafe extern "C" fn copy_cctx_internal_test_mark_tables_clean(context: *mut c_void) {
        unsafe { copy_cctx_internal_test_context(context) }
            .events
            .push("clean");
    }

    fn copy_cctx_internal_test_state(
        context: &mut CopyCCtxInternalTestContext,
        src_cctx: *const c_void,
        f_params: &ZSTD_frameParameters,
        source_stage: *const c_int,
        destination_custom_mem: *mut c_void,
        source_custom_mem: *const c_void,
        destination_hash_table: *mut *mut c_uint,
        source_hash_table: *const c_uint,
        source_hash_log: *const c_uint,
        destination_chain_table: *mut *mut c_uint,
        source_chain_table: *const c_uint,
        source_chain_log: *const c_uint,
        destination_hash_table3: *mut *mut c_uint,
        source_hash_table3: *const c_uint,
        source_hash_log3: *const c_uint,
        source_strategy: *const c_int,
        source_use_row_match_finder: *const c_int,
        destination_window: *mut c_void,
        source_window: *const c_void,
        destination_next_to_update: *mut c_uint,
        source_next_to_update: *const c_uint,
        destination_loaded_dict_end: *mut c_uint,
        source_loaded_dict_end: *const c_uint,
        destination_dict_id: *mut c_uint,
        source_dict_id: *const c_uint,
        destination_dict_content_size: *mut usize,
        source_dict_content_size: *const usize,
        destination_block_state: *mut *mut ZSTD_compressedBlockState_t,
        source_block_state: *const ZSTD_compressedBlockState_t,
    ) -> ZSTD_rust_copyCCtxInternalState {
        ZSTD_rust_copyCCtxInternalState {
            callback_context: (context as *mut CopyCCtxInternalTestContext).cast(),
            src_cctx,
            f_params,
            pledged_src_size: 123,
            source_stage,
            destination_custom_mem,
            source_custom_mem,
            reset: Some(copy_cctx_internal_test_reset),
            mark_tables_dirty: Some(copy_cctx_internal_test_mark_tables_dirty),
            mark_tables_clean: Some(copy_cctx_internal_test_mark_tables_clean),
            destination_hash_table,
            source_hash_table,
            source_hash_log,
            destination_chain_table,
            source_chain_table,
            source_chain_log,
            destination_hash_table3,
            source_hash_table3,
            source_hash_log3,
            source_strategy,
            source_use_row_match_finder,
            destination_window,
            source_window,
            destination_next_to_update,
            source_next_to_update,
            destination_loaded_dict_end,
            source_loaded_dict_end,
            destination_dict_id,
            source_dict_id,
            destination_dict_content_size,
            source_dict_content_size,
            destination_block_state,
            source_block_state,
            zbuff: 7,
        }
    }

    #[test]
    fn copy_cctx_internal_runs_private_callbacks_in_original_order() {
        let mut context = CopyCCtxInternalTestContext::default();
        let f_params = ZSTD_frameParameters {
            contentSizeFlag: 1,
            checksumFlag: 1,
            noDictIDFlag: 1,
        };
        let source_stage = ZSTD_COMPRESSION_STAGE_INIT;
        let source_custom_mem = [0x11usize, 0x22, 0x33];
        let mut destination_custom_mem = [0usize; 3];
        let source_hash_table = [11u32, 12, 13, 14];
        let mut destination_hash_table = [0u32; 4];
        let mut destination_hash_table_ptr = destination_hash_table.as_mut_ptr();
        let source_hash_log = 2;
        let source_chain_table = [21u32, 22];
        let mut destination_chain_table = [0u32; 2];
        let mut destination_chain_table_ptr = destination_chain_table.as_mut_ptr();
        let source_chain_log = 1;
        let source_hash_table3 = [31u32, 32];
        let mut destination_hash_table3 = [0u32; 2];
        let mut destination_hash_table3_ptr = destination_hash_table3.as_mut_ptr();
        let source_hash_log3 = 1;
        let source_strategy = ZSTD_DFAST;
        let source_use_row_match_finder = ZSTD_RUST_PS_DISABLE;
        let mut source_block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        source_block_state.rep = [15, 16, 17];
        source_block_state.entropy.huf.repeatMode = 2;
        source_block_state.entropy.fse.offcode_repeatMode = FSE_REPEAT_VALID;
        let source_window = ZSTD_rust_copyWindowState {
            next_src: 0x1000usize as *const c_void,
            base: 0x2000usize as *const c_void,
            dict_base: 0x3000usize as *const c_void,
            dict_limit: 21,
            low_limit: 13,
            nb_overflow_corrections: 8,
        };
        let mut destination_window = ZSTD_rust_copyWindowState {
            next_src: ptr::null(),
            base: ptr::null(),
            dict_base: ptr::null(),
            dict_limit: 0,
            low_limit: 0,
            nb_overflow_corrections: 0,
        };
        let source_next_to_update = 34;
        let mut destination_next_to_update = 0;
        let source_loaded_dict_end = 55;
        let mut destination_loaded_dict_end = 0;
        let mut destination_block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        let mut destination_block_state_slot =
            &mut destination_block_state as *mut ZSTD_compressedBlockState_t;
        let source_dict_id = 0x1234_5678;
        let mut destination_dict_id = 0;
        let source_dict_content_size = 9876;
        let mut destination_dict_content_size = 0;
        let state = copy_cctx_internal_test_state(
            &mut context,
            0x5000usize as *const c_void,
            &f_params,
            &source_stage,
            (&mut destination_custom_mem as *mut [usize; 3]).cast(),
            (&source_custom_mem as *const [usize; 3]).cast(),
            &mut destination_hash_table_ptr,
            source_hash_table.as_ptr(),
            &source_hash_log,
            &mut destination_chain_table_ptr,
            source_chain_table.as_ptr(),
            &source_chain_log,
            &mut destination_hash_table3_ptr,
            source_hash_table3.as_ptr(),
            &source_hash_log3,
            &source_strategy,
            &source_use_row_match_finder,
            (&mut destination_window as *mut ZSTD_rust_copyWindowState).cast(),
            (&source_window as *const ZSTD_rust_copyWindowState).cast(),
            &mut destination_next_to_update,
            &source_next_to_update,
            &mut destination_loaded_dict_end,
            &source_loaded_dict_end,
            &mut destination_dict_id,
            &source_dict_id,
            &mut destination_dict_content_size,
            &source_dict_content_size,
            &mut destination_block_state_slot,
            &source_block_state,
        );

        let result = unsafe { ZSTD_rust_copyCCtxInternal(&state) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["reset", "dirty", "clean"]);
        assert_eq!(context.frame_params, f_params);
        assert_eq!(context.pledged_src_size, 123);
        assert_eq!(context.zbuff, 7);
        assert_eq!(destination_custom_mem, source_custom_mem);
        assert_eq!(destination_hash_table, source_hash_table);
        assert_eq!(destination_chain_table, source_chain_table);
        assert_eq!(destination_hash_table3, source_hash_table3);
        assert_eq!(destination_window, source_window);
        assert_eq!(destination_next_to_update, source_next_to_update);
        assert_eq!(destination_loaded_dict_end, source_loaded_dict_end);
        assert_eq!(destination_dict_id, source_dict_id);
        assert_eq!(destination_dict_content_size, source_dict_content_size);
        assert_eq!(destination_block_state.rep, source_block_state.rep);
        assert_eq!(
            destination_block_state.entropy.huf.repeatMode,
            source_block_state.entropy.huf.repeatMode
        );
        assert_eq!(
            destination_block_state.entropy.fse.offcode_repeatMode,
            source_block_state.entropy.fse.offcode_repeatMode
        );
    }

    #[test]
    fn copy_cctx_internal_rejects_stage_before_mutation() {
        let mut context = CopyCCtxInternalTestContext::default();
        let f_params = ZSTD_frameParameters::default();
        let source_stage = ZSTD_COMPRESSION_STAGE_ONGOING;
        let source_custom_mem = [0usize; 3];
        let mut destination_custom_mem = [0usize; 3];
        let mut destination_block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        let mut destination_block_state_slot =
            &mut destination_block_state as *mut ZSTD_compressedBlockState_t;
        let source_block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        let source_dict_id = 0x1234_5678;
        let mut destination_dict_id = 0;
        let source_dict_content_size = 9876;
        let mut destination_dict_content_size = 0;
        let state = copy_cctx_internal_test_state(
            &mut context,
            0x5000usize as *const c_void,
            &f_params,
            &source_stage,
            (&mut destination_custom_mem as *mut [usize; 3]).cast(),
            (&source_custom_mem as *const [usize; 3]).cast(),
            ptr::dangling_mut(),
            ptr::dangling(),
            ptr::dangling(),
            ptr::dangling_mut(),
            ptr::dangling(),
            ptr::dangling(),
            ptr::dangling_mut(),
            ptr::dangling(),
            ptr::dangling(),
            ptr::dangling(),
            ptr::dangling(),
            ptr::dangling_mut(),
            ptr::dangling(),
            ptr::dangling_mut(),
            ptr::dangling(),
            ptr::dangling_mut(),
            ptr::dangling(),
            &mut destination_dict_id,
            &source_dict_id,
            &mut destination_dict_content_size,
            &source_dict_content_size,
            &mut destination_block_state_slot,
            &source_block_state,
        );

        let result = unsafe { ZSTD_rust_copyCCtxInternal(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert!(context.events.is_empty());
    }

    #[test]
    fn copy_cctx_internal_propagates_reset_error_before_table_mutation() {
        let mut context = CopyCCtxInternalTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..CopyCCtxInternalTestContext::default()
        };
        let f_params = ZSTD_frameParameters::default();
        let source_stage = ZSTD_COMPRESSION_STAGE_INIT;
        let source_custom_mem = [0usize; 3];
        let mut destination_custom_mem = [0usize; 3];
        let source_hash_log = 0;
        let source_chain_log = 0;
        let source_hash_log3 = 0;
        let source_strategy = ZSTD_DFAST;
        let source_use_row_match_finder = ZSTD_RUST_PS_DISABLE;
        let mut destination_block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        let mut destination_block_state_slot =
            &mut destination_block_state as *mut ZSTD_compressedBlockState_t;
        let source_block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        let source_dict_id = 0x1234_5678;
        let mut destination_dict_id = 0;
        let source_dict_content_size = 9876;
        let mut destination_dict_content_size = 0;
        let state = copy_cctx_internal_test_state(
            &mut context,
            0x5000usize as *const c_void,
            &f_params,
            &source_stage,
            (&mut destination_custom_mem as *mut [usize; 3]).cast(),
            (&source_custom_mem as *const [usize; 3]).cast(),
            ptr::dangling_mut(),
            ptr::dangling(),
            &source_hash_log,
            ptr::dangling_mut(),
            ptr::dangling(),
            &source_chain_log,
            ptr::dangling_mut(),
            ptr::dangling(),
            &source_hash_log3,
            &source_strategy,
            &source_use_row_match_finder,
            ptr::dangling_mut(),
            ptr::dangling(),
            ptr::dangling_mut(),
            ptr::dangling(),
            ptr::dangling_mut(),
            ptr::dangling(),
            &mut destination_dict_id,
            &source_dict_id,
            &mut destination_dict_content_size,
            &source_dict_content_size,
            &mut destination_block_state_slot,
            &source_block_state,
        );

        let result = unsafe { ZSTD_rust_copyCCtxInternal(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset"]);
    }

    #[derive(Default)]
    struct CompressAdvancedTestContext {
        events: Vec<&'static str>,
        init_params: ZSTD_parameters,
        dst: *mut c_void,
        dst_capacity: usize,
        src: *const c_void,
        src_size: usize,
        dict: *const c_void,
        dict_size: usize,
        result: usize,
    }

    unsafe extern "C" fn compress_advanced_test_init(
        context: *mut c_void,
        params: *const ZSTD_parameters,
    ) {
        let context = unsafe { &mut *context.cast::<CompressAdvancedTestContext>() };
        context.events.push("init");
        context.init_params = unsafe { *params };
    }

    unsafe extern "C" fn compress_advanced_test_internal(
        context: *mut c_void,
        dst: *mut c_void,
        dst_capacity: usize,
        src: *const c_void,
        src_size: usize,
        dict: *const c_void,
        dict_size: usize,
    ) -> usize {
        let context = unsafe { &mut *context.cast::<CompressAdvancedTestContext>() };
        context.events.push("compress");
        context.dst = dst;
        context.dst_capacity = dst_capacity;
        context.src = src;
        context.src_size = src_size;
        context.dict = dict;
        context.dict_size = dict_size;
        context.result
    }

    fn compress_advanced_test_state(
        context: &mut CompressAdvancedTestContext,
    ) -> ZSTD_rust_compressAdvancedState {
        ZSTD_rust_compressAdvancedState {
            callback_context: (context as *mut CompressAdvancedTestContext).cast(),
            init_params: Some(compress_advanced_test_init),
            compress_internal: Some(compress_advanced_test_internal),
        }
    }

    fn compress_advanced_test_params() -> ZSTD_parameters {
        ZSTD_parameters {
            cParams: ZSTD_compressionParameters {
                windowLog: 10,
                chainLog: 11,
                hashLog: 12,
                searchLog: 13,
                minMatch: 4,
                targetLength: 5,
                strategy: 1,
            },
            fParams: ZSTD_frameParameters {
                contentSizeFlag: 1,
                checksumFlag: 1,
                noDictIDFlag: 0,
            },
        }
    }

    #[test]
    fn compress_advanced_validates_then_initializes_and_compresses() {
        let mut context = CompressAdvancedTestContext {
            result: 17,
            ..CompressAdvancedTestContext::default()
        };
        let state = compress_advanced_test_state(&mut context);
        let params = compress_advanced_test_params();
        let mut dst = [0u8; 8];
        let src = [1u8, 2, 3];
        let dict = [4u8, 5];

        let result = unsafe {
            ZSTD_rust_compressAdvanced(
                &state,
                dst.as_mut_ptr().cast(),
                dst.len(),
                src.as_ptr().cast(),
                src.len(),
                dict.as_ptr().cast(),
                dict.len(),
                &params,
            )
        };

        assert_eq!(result, context.result);
        assert_eq!(context.events, ["init", "compress"]);
        assert_eq!(context.init_params, params);
        assert_eq!(context.dst, dst.as_mut_ptr().cast());
        assert_eq!(context.dst_capacity, dst.len());
        assert_eq!(context.src, src.as_ptr().cast());
        assert_eq!(context.src_size, src.len());
        assert_eq!(context.dict, dict.as_ptr().cast());
        assert_eq!(context.dict_size, dict.len());
    }

    #[test]
    fn compress_advanced_stops_before_callbacks_on_invalid_parameters() {
        let mut context = CompressAdvancedTestContext::default();
        let state = compress_advanced_test_state(&mut context);
        let mut params = compress_advanced_test_params();
        params.cParams.windowLog = 0;

        let result = unsafe {
            ZSTD_rust_compressAdvanced(
                &state,
                ptr::null_mut(),
                0,
                ptr::null(),
                0,
                ptr::null(),
                0,
                &params,
            )
        };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert!(context.events.is_empty());
    }

    #[derive(Default)]
    struct CompressBeginAdvancedTestContext {
        events: Vec<&'static str>,
        params: ZSTD_parameters,
        dict: *const c_void,
        dict_size: usize,
        cctx_params: *const c_void,
        pledged_src_size: u64,
        result: usize,
    }

    unsafe extern "C" fn compress_begin_advanced_test_init(
        context: *mut c_void,
        params: *const ZSTD_parameters,
    ) {
        let context = unsafe { &mut *context.cast::<CompressBeginAdvancedTestContext>() };
        context.events.push("init");
        context.params = unsafe { *params };
    }

    unsafe extern "C" fn compress_begin_advanced_test_begin(
        context: *mut c_void,
        dict: *const c_void,
        dict_size: usize,
        cctx_params: *const c_void,
        pledged_src_size: u64,
    ) -> usize {
        let context = unsafe { &mut *context.cast::<CompressBeginAdvancedTestContext>() };
        context.events.push("begin");
        context.dict = dict;
        context.dict_size = dict_size;
        context.cctx_params = cctx_params;
        context.pledged_src_size = pledged_src_size;
        context.result
    }

    fn compress_begin_advanced_test_state(
        context: &mut CompressBeginAdvancedTestContext,
    ) -> ZSTD_rust_compressBeginAdvancedState {
        ZSTD_rust_compressBeginAdvancedState {
            cctx: (context as *mut CompressBeginAdvancedTestContext).cast(),
            cctx_params: (context as *mut CompressBeginAdvancedTestContext).cast(),
            init_params: compress_begin_advanced_test_init,
            begin: compress_begin_advanced_test_begin,
        }
    }

    #[test]
    fn compress_begin_advanced_validates_and_preserves_init_begin_order() {
        let mut context = CompressBeginAdvancedTestContext {
            result: 29,
            ..CompressBeginAdvancedTestContext::default()
        };
        let state = compress_begin_advanced_test_state(&mut context);
        let params = compress_advanced_test_params();
        let dict = [1u8, 2, 3];

        let result = unsafe {
            ZSTD_rust_compressBeginAdvanced(&state, dict.as_ptr().cast(), dict.len(), &params, 123)
        };

        assert_eq!(result, context.result);
        assert_eq!(context.events, ["init", "begin"]);
        assert_eq!(context.params, params);
        assert_eq!(context.dict, dict.as_ptr().cast());
        assert_eq!(context.dict_size, dict.len());
        assert_eq!(
            context.cctx_params,
            (&context as *const CompressBeginAdvancedTestContext).cast()
        );
        assert_eq!(context.pledged_src_size, 123);
    }

    #[test]
    fn compress_begin_advanced_stops_before_callbacks_on_invalid_parameters() {
        let mut context = CompressBeginAdvancedTestContext::default();
        let state = compress_begin_advanced_test_state(&mut context);
        let mut params = compress_advanced_test_params();
        params.cParams.windowLog = 0;

        let result = unsafe { ZSTD_rust_compressBeginAdvanced(&state, ptr::null(), 0, &params, 0) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert!(context.events.is_empty());
    }

    #[derive(Default)]
    struct CompressUsingDictTestContext {
        events: Vec<&'static str>,
        init_params: ZSTD_parameters,
        init_level: c_int,
        dst: *mut c_void,
        dst_capacity: usize,
        src: *const c_void,
        src_size: usize,
        dict: *const c_void,
        dict_size: usize,
        result: usize,
    }

    unsafe extern "C" fn compress_using_dict_test_init(
        context: *mut c_void,
        params: *const ZSTD_parameters,
        compression_level: c_int,
    ) {
        let context = unsafe { &mut *context.cast::<CompressUsingDictTestContext>() };
        context.events.push("init");
        context.init_params = unsafe { *params };
        context.init_level = compression_level;
    }

    unsafe extern "C" fn compress_using_dict_test_internal(
        context: *mut c_void,
        dst: *mut c_void,
        dst_capacity: usize,
        src: *const c_void,
        src_size: usize,
        dict: *const c_void,
        dict_size: usize,
    ) -> usize {
        let context = unsafe { &mut *context.cast::<CompressUsingDictTestContext>() };
        context.events.push("compress");
        context.dst = dst;
        context.dst_capacity = dst_capacity;
        context.src = src;
        context.src_size = src_size;
        context.dict = dict;
        context.dict_size = dict_size;
        context.result
    }

    fn compress_using_dict_test_state(
        context: &mut CompressUsingDictTestContext,
        exclusion_mask: &u32,
    ) -> ZSTD_rust_compressUsingDictState {
        ZSTD_rust_compressUsingDictState {
            callback_context: (context as *mut CompressUsingDictTestContext).cast(),
            exclusion_mask,
            init_params: Some(compress_using_dict_test_init),
            compress_internal: Some(compress_using_dict_test_internal),
        }
    }

    #[test]
    fn compress_using_dict_selects_params_and_normalizes_default_level() {
        let mut context = CompressUsingDictTestContext {
            result: 23,
            ..CompressUsingDictTestContext::default()
        };
        let exclusion_mask = 0;
        let state = compress_using_dict_test_state(&mut context, &exclusion_mask);
        let mut dst = [0u8; 8];
        let src = [1u8, 2, 3];
        let dict = [4u8, 5];

        let result = unsafe {
            ZSTD_rust_compressUsingDict(
                &state,
                dst.as_mut_ptr().cast(),
                dst.len(),
                src.as_ptr().cast(),
                src.len(),
                dict.as_ptr().cast(),
                dict.len(),
                0,
            )
        };

        assert_eq!(result, context.result);
        assert_eq!(context.events, ["init", "compress"]);
        assert_eq!(
            context.init_params,
            ZSTD_rust_params_getParamsInternal(
                0,
                src.len() as u64,
                dict.len(),
                ZSTD_RUST_CPM_NO_ATTACH_DICT,
                exclusion_mask,
            )
        );
        assert_eq!(context.init_level, ZSTD_rust_params_defaultCLevel());
        assert_eq!(context.dst, dst.as_mut_ptr().cast());
        assert_eq!(context.dst_capacity, dst.len());
        assert_eq!(context.src, src.as_ptr().cast());
        assert_eq!(context.src_size, src.len());
        assert_eq!(context.dict, dict.as_ptr().cast());
        assert_eq!(context.dict_size, dict.len());
    }

    #[test]
    fn compress_using_dict_ignores_size_without_a_dictionary_buffer_for_params() {
        let mut context = CompressUsingDictTestContext::default();
        let exclusion_mask = 0;
        let state = compress_using_dict_test_state(&mut context, &exclusion_mask);
        let expected = ZSTD_rust_params_getParamsInternal(
            3,
            0,
            0,
            ZSTD_RUST_CPM_NO_ATTACH_DICT,
            exclusion_mask,
        );

        let result = unsafe {
            ZSTD_rust_compressUsingDict(
                &state,
                ptr::null_mut(),
                0,
                ptr::null(),
                0,
                ptr::null(),
                17,
                3,
            )
        };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["init", "compress"]);
        assert_eq!(context.init_params, expected);
        assert_eq!(context.dict, ptr::null());
        assert_eq!(context.dict_size, 17);
    }

    #[derive(Default)]
    struct ResetCStreamTestContext {
        events: Vec<&'static str>,
        reset_result: usize,
        pledged_result: usize,
        pledged_src_size: u64,
    }

    unsafe extern "C" fn reset_cstream_test_reset(context: *mut c_void) -> usize {
        let context = unsafe { &mut *context.cast::<ResetCStreamTestContext>() };
        context.events.push("reset");
        context.reset_result
    }

    unsafe extern "C" fn reset_cstream_test_set_pledged_src_size(
        context: *mut c_void,
        pledged_src_size: u64,
    ) -> usize {
        let context = unsafe { &mut *context.cast::<ResetCStreamTestContext>() };
        context.events.push("pledged");
        context.pledged_src_size = pledged_src_size;
        context.pledged_result
    }

    fn reset_cstream_test_state(
        context: &mut ResetCStreamTestContext,
    ) -> ZSTD_rust_resetCStreamState {
        ZSTD_rust_resetCStreamState {
            callback_context: (context as *mut ResetCStreamTestContext).cast(),
            reset_session: reset_cstream_test_reset,
            set_pledged_src_size: reset_cstream_test_set_pledged_src_size,
        }
    }

    #[test]
    fn reset_cstream_converts_zero_pledge_to_unknown_after_reset() {
        let mut context = ResetCStreamTestContext::default();
        let state = reset_cstream_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCStream(&state, 0) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["reset", "pledged"]);
        assert_eq!(context.pledged_src_size, ZSTD_CONTENTSIZE_UNKNOWN);
    }

    #[test]
    fn reset_cstream_forwards_nonzero_pledge() {
        let mut context = ResetCStreamTestContext::default();
        let state = reset_cstream_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCStream(&state, 123) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["reset", "pledged"]);
        assert_eq!(context.pledged_src_size, 123);
    }

    #[test]
    fn reset_cstream_stops_before_pledge_after_reset_error() {
        let mut context = ResetCStreamTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..ResetCStreamTestContext::default()
        };
        let state = reset_cstream_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCStream(&state, 123) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset"]);
        assert_eq!(context.pledged_src_size, 0);
    }

    #[test]
    fn reset_cstream_propagates_pledge_error_after_reset() {
        let mut context = ResetCStreamTestContext {
            pledged_result: ERROR(ZstdErrorCode::StageWrong),
            ..ResetCStreamTestContext::default()
        };
        let state = reset_cstream_test_state(&mut context);

        let result = unsafe { ZSTD_rust_resetCStream(&state, 123) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.events, ["reset", "pledged"]);
        assert_eq!(context.pledged_src_size, 123);
    }

    #[derive(Default)]
    struct InitCStreamUsingCDictAdvancedTestContext {
        events: Vec<&'static str>,
        reset_result: usize,
        pledged_result: usize,
        set_level_result: usize,
        load_dict_result: usize,
        check_params_result: usize,
        ref_result: usize,
        pledged_src_size: u64,
        compression_level: c_int,
        frame_params: [c_uint; 3],
        cdict: *const c_void,
        dict_size: usize,
        zstd_params: ZSTD_parameters,
    }

    unsafe fn init_cstream_using_cdict_advanced_test_context(
        context: *mut c_void,
    ) -> &'static mut InitCStreamUsingCDictAdvancedTestContext {
        unsafe { &mut *context.cast::<InitCStreamUsingCDictAdvancedTestContext>() }
    }

    unsafe extern "C" fn init_cstream_using_cdict_advanced_test_reset(
        context: *mut c_void,
    ) -> usize {
        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
        context.events.push("reset");
        context.reset_result
    }

    unsafe extern "C" fn init_cstream_using_cdict_advanced_test_set_pledged(
        context: *mut c_void,
        pledged_src_size: u64,
    ) -> usize {
        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
        context.events.push("pledged");
        context.pledged_src_size = pledged_src_size;
        context.pledged_result
    }

    unsafe extern "C" fn init_cstream_src_size_test_set_level(
        context: *mut c_void,
        compression_level: c_int,
    ) -> usize {
        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
        context.events.push("level");
        context.compression_level = compression_level;
        context.set_level_result
    }

    unsafe extern "C" fn init_cstream_using_dict_test_load_dictionary(
        context: *mut c_void,
        dict: *const c_void,
        dict_size: usize,
    ) -> usize {
        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
        context.events.push("load-dict");
        context.cdict = dict;
        context.dict_size = dict_size;
        context.load_dict_result
    }

    unsafe extern "C" fn init_cstream_advanced_test_check_c_params(
        context: *mut c_void,
        _c_params: ZSTD_compressionParameters,
    ) -> usize {
        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
        context.events.push("check");
        context.check_params_result
    }

    unsafe extern "C" fn init_cstream_advanced_test_set_zstd_params(
        context: *mut c_void,
        params: *const ZSTD_parameters,
    ) {
        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
        context.events.push("params");
        context.zstd_params = unsafe { *params };
    }

    unsafe extern "C" fn init_cstream_using_cdict_advanced_test_set_frame_params(
        context: *mut c_void,
        content_size_flag: c_uint,
        checksum_flag: c_uint,
        no_dict_id_flag: c_uint,
    ) {
        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
        context.events.push("frame");
        context.frame_params = [content_size_flag, checksum_flag, no_dict_id_flag];
    }

    unsafe extern "C" fn init_cstream_using_cdict_advanced_test_ref_cdict(
        context: *mut c_void,
        cdict: *const c_void,
    ) -> usize {
        let context = unsafe { init_cstream_using_cdict_advanced_test_context(context) };
        context.events.push("ref-cdict");
        context.cdict = cdict;
        context.ref_result
    }

    fn init_cstream_using_cdict_advanced_test_state(
        context: &mut InitCStreamUsingCDictAdvancedTestContext,
    ) -> ZSTD_rust_initCStreamUsingCDictAdvancedState {
        ZSTD_rust_initCStreamUsingCDictAdvancedState {
            callback_context: (context as *mut InitCStreamUsingCDictAdvancedTestContext).cast(),
            reset_session: init_cstream_using_cdict_advanced_test_reset,
            set_pledged_src_size: init_cstream_using_cdict_advanced_test_set_pledged,
            set_frame_params: init_cstream_using_cdict_advanced_test_set_frame_params,
            ref_cdict: init_cstream_using_cdict_advanced_test_ref_cdict,
        }
    }

    #[test]
    fn init_cstream_using_cdict_advanced_preserves_order_and_scalars() {
        let cdict = ptr::dangling::<c_void>();
        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
        let state = init_cstream_using_cdict_advanced_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamUsingCDictAdvanced(&state, 77, 1, 2, 3, cdict) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["reset", "pledged", "frame", "ref-cdict"]);
        assert_eq!(context.pledged_src_size, 77);
        assert_eq!(context.frame_params, [1, 2, 3]);
        assert_eq!(context.cdict, cdict);
    }

    #[test]
    fn init_cstream_using_cdict_advanced_stops_after_reset_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_using_cdict_advanced_test_state(&mut context);

        let result =
            unsafe { ZSTD_rust_initCStreamUsingCDictAdvanced(&state, 77, 1, 2, 3, ptr::null()) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset"]);
    }

    #[test]
    fn init_cstream_using_cdict_advanced_stops_after_pledged_size_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            pledged_result: ERROR(ZstdErrorCode::StageWrong),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_using_cdict_advanced_test_state(&mut context);

        let result =
            unsafe { ZSTD_rust_initCStreamUsingCDictAdvanced(&state, 77, 1, 2, 3, ptr::null()) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.events, ["reset", "pledged"]);
    }

    #[test]
    fn init_cstream_using_cdict_advanced_propagates_ref_error_after_frame_params() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            ref_result: ERROR(ZstdErrorCode::DictionaryCreationFailed),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_using_cdict_advanced_test_state(&mut context);

        let result =
            unsafe { ZSTD_rust_initCStreamUsingCDictAdvanced(&state, 77, 1, 2, 3, ptr::null()) };

        assert_eq!(result, ERROR(ZstdErrorCode::DictionaryCreationFailed));
        assert_eq!(context.events, ["reset", "pledged", "frame", "ref-cdict"]);
        assert_eq!(context.frame_params, [1, 2, 3]);
    }

    fn init_cstream_using_cdict_test_state(
        context: &mut InitCStreamUsingCDictAdvancedTestContext,
    ) -> ZSTD_rust_initCStreamUsingCDictState {
        ZSTD_rust_initCStreamUsingCDictState {
            callback_context: (context as *mut InitCStreamUsingCDictAdvancedTestContext).cast(),
            reset_session: init_cstream_using_cdict_advanced_test_reset,
            ref_cdict: init_cstream_using_cdict_advanced_test_ref_cdict,
        }
    }

    #[test]
    fn init_cstream_using_cdict_preserves_reset_then_reference_order() {
        let cdict = ptr::dangling::<c_void>();
        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
        let state = init_cstream_using_cdict_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamUsingCDict(&state, cdict) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["reset", "ref-cdict"]);
        assert_eq!(context.cdict, cdict);
    }

    #[test]
    fn init_cstream_using_cdict_stops_after_reset_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_using_cdict_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamUsingCDict(&state, ptr::null()) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset"]);
    }

    #[test]
    fn init_cstream_using_cdict_propagates_reference_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            ref_result: ERROR(ZstdErrorCode::DictionaryCreationFailed),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_using_cdict_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamUsingCDict(&state, ptr::null()) };

        assert_eq!(result, ERROR(ZstdErrorCode::DictionaryCreationFailed));
        assert_eq!(context.events, ["reset", "ref-cdict"]);
    }

    fn init_cstream_src_size_test_state(
        context: &mut InitCStreamUsingCDictAdvancedTestContext,
    ) -> ZSTD_rust_initCStreamSrcSizeState {
        ZSTD_rust_initCStreamSrcSizeState {
            callback_context: (context as *mut InitCStreamUsingCDictAdvancedTestContext).cast(),
            reset_session: init_cstream_using_cdict_advanced_test_reset,
            ref_cdict: init_cstream_using_cdict_advanced_test_ref_cdict,
            set_level: init_cstream_src_size_test_set_level,
            set_pledged_src_size: init_cstream_using_cdict_advanced_test_set_pledged,
        }
    }

    #[test]
    fn init_cstream_src_size_preserves_order_and_normalizes_unknown_pledge() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
        let state = init_cstream_src_size_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamSrcSize(&state, 0, -3) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["reset", "ref-cdict", "level", "pledged"]);
        assert_eq!(context.compression_level, -3);
        assert_eq!(context.pledged_src_size, ZSTD_CONTENTSIZE_UNKNOWN);
        assert_eq!(context.cdict, ptr::null());
    }

    #[test]
    fn init_cstream_src_size_stops_after_reset_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_src_size_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamSrcSize(&state, 77, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset"]);
    }

    #[test]
    fn init_cstream_src_size_stops_after_cdict_clear_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            ref_result: ERROR(ZstdErrorCode::DictionaryCreationFailed),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_src_size_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamSrcSize(&state, 77, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::DictionaryCreationFailed));
        assert_eq!(context.events, ["reset", "ref-cdict"]);
    }

    #[test]
    fn init_cstream_src_size_stops_after_level_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            set_level_result: ERROR(ZstdErrorCode::ParameterOutOfBound),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_src_size_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamSrcSize(&state, 77, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert_eq!(context.events, ["reset", "ref-cdict", "level"]);
    }

    #[test]
    fn init_cstream_src_size_propagates_pledge_error_last() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            pledged_result: ERROR(ZstdErrorCode::StageWrong),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_src_size_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamSrcSize(&state, 77, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.events, ["reset", "ref-cdict", "level", "pledged"]);
    }

    fn init_cstream_test_state(
        context: &mut InitCStreamUsingCDictAdvancedTestContext,
    ) -> ZSTD_rust_initCStreamState {
        ZSTD_rust_initCStreamState {
            callback_context: (context as *mut InitCStreamUsingCDictAdvancedTestContext).cast(),
            reset_session: init_cstream_using_cdict_advanced_test_reset,
            ref_cdict: init_cstream_using_cdict_advanced_test_ref_cdict,
            set_level: init_cstream_src_size_test_set_level,
        }
    }

    #[test]
    fn init_cstream_preserves_reset_clear_and_level_order() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
        let state = init_cstream_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStream(&state, -3) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["reset", "ref-cdict", "level"]);
        assert_eq!(context.cdict, ptr::null());
        assert_eq!(context.compression_level, -3);
    }

    #[test]
    fn init_cstream_stops_after_reset_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStream(&state, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset"]);
    }

    #[test]
    fn init_cstream_stops_after_cdict_clear_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            ref_result: ERROR(ZstdErrorCode::DictionaryCreationFailed),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStream(&state, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::DictionaryCreationFailed));
        assert_eq!(context.events, ["reset", "ref-cdict"]);
    }

    #[test]
    fn init_cstream_propagates_level_error_last() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            set_level_result: ERROR(ZstdErrorCode::ParameterOutOfBound),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStream(&state, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert_eq!(context.events, ["reset", "ref-cdict", "level"]);
    }

    fn init_cstream_using_dict_test_state(
        context: &mut InitCStreamUsingCDictAdvancedTestContext,
    ) -> ZSTD_rust_initCStreamUsingDictState {
        ZSTD_rust_initCStreamUsingDictState {
            callback_context: (context as *mut InitCStreamUsingCDictAdvancedTestContext).cast(),
            reset_session: init_cstream_using_cdict_advanced_test_reset,
            set_level: init_cstream_src_size_test_set_level,
            load_dictionary: init_cstream_using_dict_test_load_dictionary,
        }
    }

    #[test]
    fn init_cstream_using_dict_preserves_order_and_dictionary_arguments() {
        let dict = ptr::dangling::<c_void>();
        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
        let state = init_cstream_using_dict_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamUsingDict(&state, dict, 123, -3) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["reset", "level", "load-dict"]);
        assert_eq!(context.compression_level, -3);
        assert_eq!(context.cdict, dict);
        assert_eq!(context.dict_size, 123);
    }

    #[test]
    fn init_cstream_using_dict_stops_after_reset_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_using_dict_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamUsingDict(&state, ptr::null(), 0, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset"]);
    }

    #[test]
    fn init_cstream_using_dict_stops_after_level_error() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            set_level_result: ERROR(ZstdErrorCode::ParameterOutOfBound),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_using_dict_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamUsingDict(&state, ptr::null(), 0, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert_eq!(context.events, ["reset", "level"]);
    }

    #[test]
    fn init_cstream_using_dict_propagates_dictionary_error_last() {
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            load_dict_result: ERROR(ZstdErrorCode::DictionaryCreationFailed),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_using_dict_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamUsingDict(&state, ptr::null(), 0, 4) };

        assert_eq!(result, ERROR(ZstdErrorCode::DictionaryCreationFailed));
        assert_eq!(context.events, ["reset", "level", "load-dict"]);
    }

    fn init_cstream_advanced_test_state(
        context: &mut InitCStreamUsingCDictAdvancedTestContext,
    ) -> ZSTD_rust_initCStreamAdvancedState {
        ZSTD_rust_initCStreamAdvancedState {
            callback_context: (context as *mut InitCStreamUsingCDictAdvancedTestContext).cast(),
            reset_session: init_cstream_using_cdict_advanced_test_reset,
            set_pledged_src_size: init_cstream_using_cdict_advanced_test_set_pledged,
            check_c_params: init_cstream_advanced_test_check_c_params,
            set_zstd_params: init_cstream_advanced_test_set_zstd_params,
            load_dictionary: init_cstream_using_dict_test_load_dictionary,
        }
    }

    fn init_cstream_advanced_test_params(content_size_flag: c_int) -> ZSTD_parameters {
        ZSTD_parameters {
            cParams: ZSTD_compressionParameters {
                windowLog: 10,
                chainLog: 11,
                hashLog: 12,
                searchLog: 13,
                minMatch: 4,
                targetLength: 5,
                strategy: 1,
            },
            fParams: ZSTD_frameParameters {
                contentSizeFlag: content_size_flag,
                checksumFlag: 1,
                noDictIDFlag: 2,
            },
        }
    }

    #[test]
    fn init_cstream_advanced_preserves_order_and_normalizes_unknown_pledge() {
        let params = init_cstream_advanced_test_params(0);
        let dict = ptr::dangling::<c_void>();
        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
        let state = init_cstream_advanced_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 0, dict, 123) };

        assert_eq!(result, 0);
        assert_eq!(
            context.events,
            ["reset", "pledged", "check", "params", "load-dict"]
        );
        assert_eq!(context.pledged_src_size, ZSTD_CONTENTSIZE_UNKNOWN);
        assert_eq!(context.zstd_params, params);
        assert_eq!(context.cdict, dict);
        assert_eq!(context.dict_size, 123);
    }

    #[test]
    fn init_cstream_advanced_keeps_zero_pledge_for_known_empty_frame() {
        let params = init_cstream_advanced_test_params(1);
        let mut context = InitCStreamUsingCDictAdvancedTestContext::default();
        let state = init_cstream_advanced_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 0, ptr::null(), 0) };

        assert_eq!(result, 0);
        assert_eq!(context.pledged_src_size, 0);
        assert_eq!(
            context.events,
            ["reset", "pledged", "check", "params", "load-dict"]
        );
    }

    #[test]
    fn init_cstream_advanced_stops_after_reset_error() {
        let params = init_cstream_advanced_test_params(0);
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_advanced_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 77, ptr::null(), 0) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(context.events, ["reset"]);
    }

    #[test]
    fn init_cstream_advanced_stops_after_pledged_size_error() {
        let params = init_cstream_advanced_test_params(0);
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            pledged_result: ERROR(ZstdErrorCode::StageWrong),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_advanced_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 77, ptr::null(), 0) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.events, ["reset", "pledged"]);
    }

    #[test]
    fn init_cstream_advanced_stops_after_parameter_error() {
        let params = init_cstream_advanced_test_params(0);
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            check_params_result: ERROR(ZstdErrorCode::ParameterOutOfBound),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_advanced_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 77, ptr::null(), 0) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert_eq!(context.events, ["reset", "pledged", "check"]);
    }

    #[test]
    fn init_cstream_advanced_propagates_dictionary_error_last() {
        let params = init_cstream_advanced_test_params(0);
        let mut context = InitCStreamUsingCDictAdvancedTestContext {
            load_dict_result: ERROR(ZstdErrorCode::DictionaryCreationFailed),
            ..InitCStreamUsingCDictAdvancedTestContext::default()
        };
        let state = init_cstream_advanced_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCStreamAdvanced(&state, &params, 77, ptr::null(), 0) };

        assert_eq!(result, ERROR(ZstdErrorCode::DictionaryCreationFailed));
        assert_eq!(
            context.events,
            ["reset", "pledged", "check", "params", "load-dict"]
        );
    }

    fn set_parameters_using_cctx_params_test_value(params: &ZSTD_CCtx_params) -> c_int {
        let mut value = -1;
        let result = unsafe { ZSTD_CCtxParams_getParameter(params, 10, &mut value) };
        assert_eq!(result, 0);
        value
    }

    fn set_parameters_using_cctx_params_test_state(
        requested_params: &mut ZSTD_CCtx_params,
        source_params: &ZSTD_CCtx_params,
        stream_stage: c_int,
        cdict: *const c_void,
    ) -> ZSTD_rust_setParametersUsingCCtxParamsState {
        ZSTD_rust_setParametersUsingCCtxParamsState {
            requested_params,
            source_params,
            stream_stage,
            cdict,
        }
    }

    #[test]
    fn set_parameters_using_cctx_params_copies_source_after_policy_checks() {
        let mut source_params = unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        assert_eq!(
            unsafe { ZSTD_CCtxParams_setParameter(&mut source_params, 10, 1) },
            1
        );
        let state = set_parameters_using_cctx_params_test_state(
            &mut requested_params,
            &source_params,
            ZSTD_CSTREAM_STAGE_INIT,
            ptr::null(),
        );

        let result = unsafe { ZSTD_rust_setParametersUsingCCtxParams(&state) };

        assert_eq!(result, 0);
        assert_eq!(
            set_parameters_using_cctx_params_test_value(&requested_params),
            1
        );
    }

    #[test]
    fn set_parameters_using_cctx_params_rejects_non_init_stage_without_copying() {
        let mut source_params = unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        assert_eq!(
            unsafe { ZSTD_CCtxParams_setParameter(&mut source_params, 10, 1) },
            1
        );
        let state = set_parameters_using_cctx_params_test_state(
            &mut requested_params,
            &source_params,
            ZSTD_CSTREAM_STAGE_LOAD,
            ptr::null(),
        );

        let result = unsafe { ZSTD_rust_setParametersUsingCCtxParams(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(
            set_parameters_using_cctx_params_test_value(&requested_params),
            0
        );
    }

    #[test]
    fn set_parameters_using_cctx_params_rejects_cdict_without_copying() {
        let mut source_params = unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        assert_eq!(
            unsafe { ZSTD_CCtxParams_setParameter(&mut source_params, 10, 1) },
            1
        );
        let state = set_parameters_using_cctx_params_test_state(
            &mut requested_params,
            &source_params,
            ZSTD_CSTREAM_STAGE_INIT,
            ptr::dangling(),
        );

        let result = unsafe { ZSTD_rust_setParametersUsingCCtxParams(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(
            set_parameters_using_cctx_params_test_value(&requested_params),
            0
        );
    }

    #[test]
    fn set_parameters_using_cctx_params_rejects_null_state() {
        let result = unsafe { ZSTD_rust_setParametersUsingCCtxParams(ptr::null()) };

        assert_eq!(result, ERROR(ZstdErrorCode::Generic));
    }

    fn set_parameter_test_state(
        requested_params: &mut ZSTD_CCtx_params,
        stream_stage: c_int,
        c_params_changed: &mut c_int,
        static_size: usize,
        max_block_size_set: &mut c_uint,
    ) -> ZSTD_rust_setParameterState {
        ZSTD_rust_setParameterState {
            requested_params,
            stream_stage,
            c_params_changed,
            static_size,
            rust_simple_compress2_max_block_size_set: max_block_size_set,
        }
    }

    fn set_parameter_test_get(requested_params: &ZSTD_CCtx_params, param: c_int) -> (usize, c_int) {
        let mut value = -1;
        let result = unsafe { ZSTD_CCtxParams_getParameter(requested_params, param, &mut value) };
        (result, value)
    }

    #[test]
    fn set_parameter_authorizes_in_flight_updates_and_marks_cparams_changed() {
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut c_params_changed = 0;
        let mut max_block_size_set = 0;
        let state = set_parameter_test_state(
            &mut requested_params,
            ZSTD_CSTREAM_STAGE_LOAD,
            &mut c_params_changed,
            0,
            &mut max_block_size_set,
        );

        let result = unsafe { ZSTD_rust_setParameter(&state, ZSTD_C_COMPRESSION_LEVEL, 5) };

        assert_eq!(result, 5);
        assert_eq!(c_params_changed, 1);
        assert_eq!(max_block_size_set, 0);
        assert_eq!(
            set_parameter_test_get(&requested_params, ZSTD_C_COMPRESSION_LEVEL),
            (0, 5)
        );
    }

    #[test]
    fn set_parameter_rejects_unauthorized_stage_updates_without_mutation() {
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut c_params_changed = 0;
        let mut max_block_size_set = 0;
        let state = set_parameter_test_state(
            &mut requested_params,
            ZSTD_CSTREAM_STAGE_LOAD,
            &mut c_params_changed,
            0,
            &mut max_block_size_set,
        );

        let result = unsafe { ZSTD_rust_setParameter(&state, ZSTD_C_FORMAT, 1) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(c_params_changed, 0);
        assert_eq!(
            set_parameter_test_get(&requested_params, ZSTD_C_FORMAT),
            (0, 0)
        );
    }

    #[test]
    fn set_parameter_rejects_nonzero_workers_for_static_contexts() {
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut c_params_changed = 0;
        let mut max_block_size_set = 0;
        let state = set_parameter_test_state(
            &mut requested_params,
            ZSTD_CSTREAM_STAGE_INIT,
            &mut c_params_changed,
            1,
            &mut max_block_size_set,
        );

        let result = unsafe { ZSTD_rust_setParameter(&state, ZSTD_C_NB_WORKERS, 1) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterUnsupported));
        assert_eq!(c_params_changed, 0);
        assert_eq!(
            set_parameter_test_get(&requested_params, ZSTD_C_FORMAT),
            (0, 0)
        );
    }

    #[test]
    fn set_parameter_rejects_unknown_parameters() {
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut c_params_changed = 0;
        let mut max_block_size_set = 0;
        let state = set_parameter_test_state(
            &mut requested_params,
            ZSTD_CSTREAM_STAGE_INIT,
            &mut c_params_changed,
            0,
            &mut max_block_size_set,
        );

        let result = unsafe { ZSTD_rust_setParameter(&state, 12345, 1) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterUnsupported));
        assert_eq!(
            set_parameter_test_get(&requested_params, ZSTD_C_FORMAT),
            (0, 0)
        );
    }

    #[test]
    fn set_parameter_marks_max_block_size_after_success() {
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut c_params_changed = 0;
        let mut max_block_size_set = 0;
        let state = set_parameter_test_state(
            &mut requested_params,
            ZSTD_CSTREAM_STAGE_INIT,
            &mut c_params_changed,
            0,
            &mut max_block_size_set,
        );

        let result = unsafe { ZSTD_rust_setParameter(&state, ZSTD_C_MAX_BLOCK_SIZE, 0) };

        assert_eq!(result, 0);
        assert_eq!(max_block_size_set, 1);
    }

    #[test]
    fn set_parameter_does_not_mark_max_block_size_after_underlying_error() {
        let mut requested_params =
            unsafe { MaybeUninit::<ZSTD_CCtx_params>::zeroed().assume_init() };
        let mut c_params_changed = 0;
        let mut max_block_size_set = 0;
        let state = set_parameter_test_state(
            &mut requested_params,
            ZSTD_CSTREAM_STAGE_INIT,
            &mut c_params_changed,
            0,
            &mut max_block_size_set,
        );

        let result = unsafe { ZSTD_rust_setParameter(&state, ZSTD_C_MAX_BLOCK_SIZE, 1) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert_eq!(max_block_size_set, 0);
    }

    fn ref_thread_pool_test_state(
        pool: &mut *mut c_void,
        requested_pool: *mut c_void,
        stream_stage: c_int,
    ) -> ZSTD_rust_refThreadPoolState {
        ZSTD_rust_refThreadPoolState {
            pool,
            requested_pool,
            stream_stage,
        }
    }

    #[test]
    fn ref_thread_pool_assigns_the_requested_pool_at_init_stage() {
        let mut pool = ptr::null_mut::<c_void>();
        let requested_pool = ptr::dangling_mut::<c_void>();
        let state = ref_thread_pool_test_state(&mut pool, requested_pool, ZSTD_CSTREAM_STAGE_INIT);

        let result = unsafe { ZSTD_rust_refThreadPool(&state) };

        assert_eq!(result, 0);
        assert_eq!(pool, requested_pool);
    }

    #[test]
    fn ref_thread_pool_rejects_non_init_stage_without_mutating_the_pool() {
        let original_pool = ptr::dangling_mut::<c_void>();
        let mut pool = original_pool;
        let state = ref_thread_pool_test_state(&mut pool, ptr::null_mut(), ZSTD_CSTREAM_STAGE_LOAD);

        let result = unsafe { ZSTD_rust_refThreadPool(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(pool, original_pool);
    }

    #[test]
    fn ref_thread_pool_rejects_null_state() {
        let result = unsafe { ZSTD_rust_refThreadPool(ptr::null()) };

        assert_eq!(result, ERROR(ZstdErrorCode::Generic));
    }

    #[derive(Default)]
    struct CreateCCtxTestContext {
        events: Vec<&'static str>,
        valid: c_int,
        allocation: *mut c_void,
        requested_size: usize,
        initialized: *mut c_void,
    }

    unsafe extern "C" fn create_cctx_test_validate(context: *mut c_void) -> c_int {
        let context = unsafe { &mut *context.cast::<CreateCCtxTestContext>() };
        context.events.push("validate");
        context.valid
    }

    unsafe extern "C" fn create_cctx_test_allocate(
        context: *mut c_void,
        size: usize,
    ) -> *mut c_void {
        let context = unsafe { &mut *context.cast::<CreateCCtxTestContext>() };
        context.events.push("allocate");
        context.requested_size = size;
        context.allocation
    }

    unsafe extern "C" fn create_cctx_test_init(context: *mut c_void, cctx: *mut c_void) {
        let context = unsafe { &mut *context.cast::<CreateCCtxTestContext>() };
        context.events.push("init");
        context.initialized = cctx;
    }

    fn create_cctx_test_state(context: &mut CreateCCtxTestContext) -> ZSTD_rust_createCCtxState {
        ZSTD_rust_createCCtxState {
            callback_context: (context as *mut CreateCCtxTestContext).cast(),
            cctx_size: 123,
            validate_custom_mem: create_cctx_test_validate,
            allocate: create_cctx_test_allocate,
            init: create_cctx_test_init,
        }
    }

    #[test]
    fn create_cctx_validates_allocates_and_initializes_in_order() {
        let allocation = ptr::dangling_mut::<c_void>();
        let mut context = CreateCCtxTestContext {
            valid: 1,
            allocation,
            ..Default::default()
        };
        let state = create_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_createCCtx(&state) };

        assert_eq!(result, allocation);
        assert_eq!(context.events, ["validate", "allocate", "init"]);
        assert_eq!(context.requested_size, 123);
        assert_eq!(context.initialized, allocation);
    }

    #[test]
    fn create_cctx_stops_before_allocation_for_invalid_memory_callbacks() {
        let mut context = CreateCCtxTestContext {
            valid: 0,
            allocation: ptr::dangling_mut(),
            ..Default::default()
        };
        let state = create_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_createCCtx(&state) };

        assert!(result.is_null());
        assert_eq!(context.events, ["validate"]);
        assert_eq!(context.requested_size, 0);
        assert!(context.initialized.is_null());
    }

    #[test]
    fn create_cctx_stops_before_initialization_after_allocation_failure() {
        let mut context = CreateCCtxTestContext {
            valid: 1,
            ..Default::default()
        };
        let state = create_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_createCCtx(&state) };

        assert!(result.is_null());
        assert_eq!(context.events, ["validate", "allocate"]);
        assert_eq!(context.requested_size, 123);
        assert!(context.initialized.is_null());
    }

    #[derive(Default)]
    struct CreateCDictAdvancedWrapperTestContext {
        events: Vec<&'static str>,
        init_context: *mut c_void,
        init_cctx_params: *mut c_void,
        init_c_params: *const ZSTD_compressionParameters,
        init_custom_mem: *const c_void,
        init_dict_size: usize,
        init_dict_content_type: c_int,
        create_context: *mut c_void,
        create_dict: *const c_void,
        create_dict_size: usize,
        create_dict_load_method: c_int,
        create_dict_content_type: c_int,
        create_cctx_params: *const c_void,
        create_custom_mem: *const c_void,
        result: *mut c_void,
    }

    unsafe extern "C" fn create_cdict_advanced_wrapper_test_init(
        context: *mut c_void,
        cctx_params: *mut c_void,
        c_params: *const ZSTD_compressionParameters,
        custom_mem: *const c_void,
        dict_size: usize,
        dict_content_type: c_int,
    ) {
        let context = unsafe { &mut *context.cast::<CreateCDictAdvancedWrapperTestContext>() };
        context.events.push("init");
        context.init_context = context as *mut _ as *mut c_void;
        context.init_cctx_params = cctx_params;
        context.init_c_params = c_params;
        context.init_custom_mem = custom_mem;
        context.init_dict_size = dict_size;
        context.init_dict_content_type = dict_content_type;
    }

    unsafe extern "C" fn create_cdict_advanced_wrapper_test_create(
        context: *mut c_void,
        dict: *const c_void,
        dict_size: usize,
        dict_load_method: c_int,
        dict_content_type: c_int,
        cctx_params: *const c_void,
        custom_mem: *const c_void,
    ) -> *mut c_void {
        let context = unsafe { &mut *context.cast::<CreateCDictAdvancedWrapperTestContext>() };
        context.events.push("create");
        context.create_context = context as *mut _ as *mut c_void;
        context.create_dict = dict;
        context.create_dict_size = dict_size;
        context.create_dict_load_method = dict_load_method;
        context.create_dict_content_type = dict_content_type;
        context.create_cctx_params = cctx_params;
        context.create_custom_mem = custom_mem;
        context.result
    }

    fn create_cdict_advanced_wrapper_test_state(
        context: &mut CreateCDictAdvancedWrapperTestContext,
        cctx_params: *mut c_void,
        c_params: *const ZSTD_compressionParameters,
        custom_mem: *const c_void,
    ) -> ZSTD_rust_createCDictAdvancedWrapperState {
        ZSTD_rust_createCDictAdvancedWrapperState {
            callback_context: context as *mut _ as *mut c_void,
            cctx_params,
            c_params,
            custom_mem,
            init_params: create_cdict_advanced_wrapper_test_init,
            create: create_cdict_advanced_wrapper_test_create,
        }
    }

    #[test]
    fn create_cdict_advanced_wrapper_preserves_prepare_then_create_order() {
        let mut context = CreateCDictAdvancedWrapperTestContext {
            result: ptr::dangling_mut(),
            ..Default::default()
        };
        let cctx_params = ptr::dangling_mut::<c_void>();
        let c_params = ptr::dangling::<ZSTD_compressionParameters>();
        let custom_mem = ptr::dangling::<c_void>();
        let dict = ptr::dangling::<u8>().cast::<c_void>();
        let state = create_cdict_advanced_wrapper_test_state(
            &mut context,
            cctx_params,
            c_params,
            custom_mem,
        );

        let result = unsafe { ZSTD_rust_createCDictAdvancedWrapper(&state, dict, 123, 1, 2) };

        assert_eq!(result, context.result);
        assert_eq!(context.events, ["init", "create"]);
        assert_eq!(context.init_context, state.callback_context);
        assert_eq!(context.init_cctx_params, cctx_params);
        assert_eq!(context.init_c_params, c_params);
        assert_eq!(context.init_custom_mem, custom_mem);
        assert_eq!(context.init_dict_size, 123);
        assert_eq!(context.init_dict_content_type, 2);
        assert_eq!(context.create_context, state.callback_context);
        assert_eq!(context.create_dict, dict);
        assert_eq!(context.create_dict_size, 123);
        assert_eq!(context.create_dict_load_method, 1);
        assert_eq!(context.create_dict_content_type, 2);
        assert_eq!(context.create_cctx_params, cctx_params);
        assert_eq!(context.create_custom_mem, custom_mem);
    }

    #[test]
    fn create_cdict_advanced_wrapper_rejects_missing_parameter_storage() {
        let mut context = CreateCDictAdvancedWrapperTestContext::default();
        let c_params = ptr::dangling::<ZSTD_compressionParameters>();
        let custom_mem = ptr::dangling::<c_void>();
        let state = create_cdict_advanced_wrapper_test_state(
            &mut context,
            ptr::null_mut(),
            c_params,
            custom_mem,
        );

        let result = unsafe { ZSTD_rust_createCDictAdvancedWrapper(&state, ptr::null(), 0, 0, 0) };

        assert!(result.is_null());
        assert!(context.events.is_empty());
    }

    #[derive(Default)]
    struct InitCCtxTestContext {
        events: Vec<&'static str>,
        reset_result: usize,
    }

    unsafe fn init_cctx_test_context(context: *mut c_void) -> &'static mut InitCCtxTestContext {
        unsafe { &mut *context.cast::<InitCCtxTestContext>() }
    }

    unsafe extern "C" fn init_cctx_test_zero(context: *mut c_void) {
        unsafe { init_cctx_test_context(context) }
            .events
            .push("zero");
    }

    unsafe extern "C" fn init_cctx_test_set_custom_mem(
        context: *mut c_void,
        _custom_mem: *const c_void,
    ) {
        unsafe { init_cctx_test_context(context) }
            .events
            .push("set-custom-mem");
    }

    unsafe extern "C" fn init_cctx_test_set_bmi2(context: *mut c_void) {
        unsafe { init_cctx_test_context(context) }
            .events
            .push("set-bmi2");
    }

    unsafe extern "C" fn init_cctx_test_reset(context: *mut c_void) -> usize {
        let context = unsafe { init_cctx_test_context(context) };
        context.events.push("reset");
        context.reset_result
    }

    fn init_cctx_test_state(context: &mut InitCCtxTestContext) -> ZSTD_rust_initCCtxState {
        ZSTD_rust_initCCtxState {
            callback_context: (context as *mut InitCCtxTestContext).cast(),
            custom_mem: ptr::dangling(),
            zero: init_cctx_test_zero,
            set_custom_mem: init_cctx_test_set_custom_mem,
            set_bmi2: init_cctx_test_set_bmi2,
            reset: init_cctx_test_reset,
        }
    }

    #[test]
    fn init_cctx_runs_private_initialization_steps_in_order() {
        let mut context = InitCCtxTestContext::default();
        let state = init_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCCtx(&state) };

        assert_eq!(result, 0);
        assert_eq!(
            context.events,
            ["zero", "set-custom-mem", "set-bmi2", "reset"]
        );
    }

    #[test]
    fn init_cctx_propagates_reset_errors_after_initialization_steps() {
        let mut context = InitCCtxTestContext {
            reset_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..Default::default()
        };
        let state = init_cctx_test_state(&mut context);

        let result = unsafe { ZSTD_rust_initCCtx(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert_eq!(
            context.events,
            ["zero", "set-custom-mem", "set-bmi2", "reset"]
        );
    }

    #[derive(Default)]
    struct InitStaticCCtxTestContext {
        events: Vec<&'static str>,
        result: *mut c_void,
    }

    unsafe extern "C" fn init_static_cctx_test_init(context: *mut c_void) -> *mut c_void {
        let context = unsafe { &mut *context.cast::<InitStaticCCtxTestContext>() };
        context.events.push("init");
        context.result
    }

    fn init_static_cctx_test_state(
        context: &mut InitStaticCCtxTestContext,
        workspace: *mut c_void,
        workspace_size: usize,
        cctx_size: usize,
    ) -> ZSTD_rust_initStaticCCtxState {
        ZSTD_rust_initStaticCCtxState {
            callback_context: (context as *mut InitStaticCCtxTestContext).cast(),
            workspace,
            workspace_size,
            cctx_size,
            init: init_static_cctx_test_init,
        }
    }

    #[test]
    fn init_static_cctx_rejects_an_unaligned_workspace_before_callback() {
        let mut context = InitStaticCCtxTestContext {
            result: ptr::dangling_mut(),
            ..Default::default()
        };
        let mut workspace = [0usize; 2];
        let unaligned_workspace = workspace.as_mut_ptr().cast::<u8>().wrapping_add(1).cast();
        let state = init_static_cctx_test_state(&mut context, unaligned_workspace, usize::MAX, 0);

        let result = unsafe { ZSTD_rust_initStaticCCtx(&state) };

        assert!(result.is_null());
        assert!(context.events.is_empty());
    }

    #[test]
    fn init_static_cctx_rejects_a_small_workspace_before_callback() {
        let mut context = InitStaticCCtxTestContext {
            result: ptr::dangling_mut(),
            ..Default::default()
        };
        let mut workspace = [0usize; 1];
        let state = init_static_cctx_test_state(
            &mut context,
            workspace.as_mut_ptr().cast(),
            size_of_val(&workspace),
            size_of_val(&workspace),
        );

        let result = unsafe { ZSTD_rust_initStaticCCtx(&state) };

        assert!(result.is_null());
        assert!(context.events.is_empty());
    }

    #[test]
    fn init_static_cctx_calls_the_initializer_after_workspace_validation() {
        let mut context = InitStaticCCtxTestContext {
            result: ptr::dangling_mut(),
            ..Default::default()
        };
        let mut workspace = [0usize; 1];
        let state = init_static_cctx_test_state(
            &mut context,
            workspace.as_mut_ptr().cast(),
            size_of_val(&workspace),
            size_of_val(&workspace) - 1,
        );

        let result = unsafe { ZSTD_rust_initStaticCCtx(&state) };

        assert_eq!(result, context.result);
        assert_eq!(context.events, ["init"]);
    }

    #[test]
    fn init_static_cctx_rejects_a_null_workspace() {
        let mut context = InitStaticCCtxTestContext {
            result: ptr::dangling_mut(),
            ..Default::default()
        };
        let state = init_static_cctx_test_state(&mut context, ptr::null_mut(), usize::MAX, 0);

        let result = unsafe { ZSTD_rust_initStaticCCtx(&state) };

        assert!(result.is_null());
        assert!(context.events.is_empty());
    }

    #[derive(Default)]
    struct FreeCCtxTestContext {
        events: Vec<&'static str>,
    }

    unsafe extern "C" fn free_cctx_test_content(context: *mut c_void) {
        let context = unsafe { &mut *context.cast::<FreeCCtxTestContext>() };
        context.events.push("content");
    }

    unsafe extern "C" fn free_cctx_test_object(context: *mut c_void) {
        let context = unsafe { &mut *context.cast::<FreeCCtxTestContext>() };
        context.events.push("object");
    }

    fn free_cctx_test_state(
        context: *mut c_void,
        static_size: usize,
        cctx_in_workspace: c_int,
    ) -> ZSTD_rust_freeCCtxState {
        ZSTD_rust_freeCCtxState {
            callback_context: context,
            static_size,
            cctx_in_workspace,
            free_content: free_cctx_test_content,
            free_object: free_cctx_test_object,
        }
    }

    #[test]
    fn free_cctx_frees_content_before_an_external_object() {
        let mut context = FreeCCtxTestContext::default();
        let state = free_cctx_test_state((&mut context as *mut FreeCCtxTestContext).cast(), 0, 0);

        let result = unsafe { ZSTD_rust_freeCCtx(&state) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["content", "object"]);
    }

    #[test]
    fn free_cctx_skips_the_external_object_when_embedded_in_workspace() {
        let mut context = FreeCCtxTestContext::default();
        let state = free_cctx_test_state((&mut context as *mut FreeCCtxTestContext).cast(), 0, 1);

        let result = unsafe { ZSTD_rust_freeCCtx(&state) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["content"]);
    }

    #[test]
    fn free_cctx_rejects_static_contexts_before_any_callback() {
        let mut context = FreeCCtxTestContext::default();
        let state = free_cctx_test_state((&mut context as *mut FreeCCtxTestContext).cast(), 1, 0);

        let result = unsafe { ZSTD_rust_freeCCtx(&state) };

        assert_eq!(result, ERROR(ZstdErrorCode::MemoryAllocation));
        assert!(context.events.is_empty());
    }

    #[test]
    fn free_cctx_accepts_a_null_context() {
        let state = free_cctx_test_state(ptr::null_mut(), 0, 0);

        let result = unsafe { ZSTD_rust_freeCCtx(&state) };

        assert_eq!(result, 0);
    }

    #[derive(Default)]
    struct SetCParamsTestContext {
        events: Vec<&'static str>,
        parameter_calls: Vec<(c_int, c_int)>,
        check_result: usize,
        set_result: usize,
        fail_at: usize,
    }

    unsafe fn set_cparams_test_context(context: *mut c_void) -> &'static mut SetCParamsTestContext {
        unsafe { &mut *context.cast::<SetCParamsTestContext>() }
    }

    unsafe extern "C" fn set_cparams_test_check(
        context: *mut c_void,
        _cparams: ZSTD_compressionParameters,
    ) -> usize {
        let context = unsafe { set_cparams_test_context(context) };
        context.events.push("check");
        context.check_result
    }

    unsafe extern "C" fn set_cparams_test_set_parameter(
        context: *mut c_void,
        param: c_int,
        value: c_int,
    ) -> usize {
        let context = unsafe { set_cparams_test_context(context) };
        context.events.push("set");
        context.parameter_calls.push((param, value));
        if context.fail_at != 0 && context.parameter_calls.len() == context.fail_at {
            context.set_result
        } else {
            0
        }
    }

    fn set_cparams_test_state(context: &mut SetCParamsTestContext) -> ZSTD_rust_setCParamsState {
        ZSTD_rust_setCParamsState {
            callback_context: (context as *mut SetCParamsTestContext).cast(),
            check_c_params: set_cparams_test_check,
            set_parameter: set_cparams_test_set_parameter,
        }
    }

    fn set_cparams_test_params() -> ZSTD_compressionParameters {
        ZSTD_compressionParameters {
            windowLog: 10,
            chainLog: 11,
            hashLog: 12,
            searchLog: 13,
            minMatch: 4,
            targetLength: 5,
            strategy: 6,
        }
    }

    #[test]
    fn set_cparams_preserves_validation_and_parameter_order() {
        let cparams = set_cparams_test_params();
        let mut context = SetCParamsTestContext::default();
        let state = set_cparams_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setCParams(&state, cparams) };

        assert_eq!(result, 0);
        assert_eq!(
            context.events,
            ["check", "set", "set", "set", "set", "set", "set", "set"]
        );
        assert_eq!(
            context.parameter_calls,
            [
                (ZSTD_C_WINDOW_LOG, 10),
                (ZSTD_C_CHAIN_LOG, 11),
                (ZSTD_C_HASH_LOG, 12),
                (ZSTD_C_SEARCH_LOG, 13),
                (ZSTD_C_MIN_MATCH, 4),
                (ZSTD_C_TARGET_LENGTH, 5),
                (ZSTD_C_STRATEGY, 6),
            ]
        );
    }

    #[test]
    fn set_cparams_stops_before_updates_after_validation_error() {
        let cparams = set_cparams_test_params();
        let mut context = SetCParamsTestContext {
            check_result: ERROR(ZstdErrorCode::ParameterOutOfBound),
            ..SetCParamsTestContext::default()
        };
        let state = set_cparams_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setCParams(&state, cparams) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert_eq!(context.events, ["check"]);
        assert!(context.parameter_calls.is_empty());
    }

    #[test]
    fn set_cparams_propagates_parameter_error_after_prior_updates() {
        let cparams = set_cparams_test_params();
        let mut context = SetCParamsTestContext {
            set_result: ERROR(ZstdErrorCode::StageWrong),
            fail_at: 4,
            ..SetCParamsTestContext::default()
        };
        let state = set_cparams_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setCParams(&state, cparams) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.events, ["check", "set", "set", "set", "set"]);
        assert_eq!(context.parameter_calls.len(), 4);
    }

    #[derive(Default)]
    struct SetFParamsTestContext {
        parameter_calls: Vec<(c_int, c_int)>,
        set_result: usize,
        fail_at: usize,
    }

    unsafe fn set_fparams_test_context(context: *mut c_void) -> &'static mut SetFParamsTestContext {
        unsafe { &mut *context.cast::<SetFParamsTestContext>() }
    }

    unsafe extern "C" fn set_fparams_test_set_parameter(
        context: *mut c_void,
        param: c_int,
        value: c_int,
    ) -> usize {
        let context = unsafe { set_fparams_test_context(context) };
        context.parameter_calls.push((param, value));
        if context.fail_at != 0 && context.parameter_calls.len() == context.fail_at {
            context.set_result
        } else {
            0
        }
    }

    fn set_fparams_test_state(context: &mut SetFParamsTestContext) -> ZSTD_rust_setFParamsState {
        ZSTD_rust_setFParamsState {
            callback_context: (context as *mut SetFParamsTestContext).cast(),
            set_parameter: set_fparams_test_set_parameter,
        }
    }

    #[test]
    fn set_fparams_preserves_parameter_order_and_boolean_conversions() {
        let fparams = ZSTD_frameParameters {
            contentSizeFlag: 0,
            checksumFlag: 2,
            noDictIDFlag: 7,
        };
        let mut context = SetFParamsTestContext::default();
        let state = set_fparams_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setFParams(&state, fparams) };

        assert_eq!(result, 0);
        assert_eq!(
            context.parameter_calls,
            [
                (ZSTD_C_CONTENT_SIZE_FLAG, 0),
                (ZSTD_C_CHECKSUM_FLAG, 1),
                (ZSTD_C_DICT_ID_FLAG, 0),
            ]
        );
    }

    #[test]
    fn set_fparams_stops_after_the_first_parameter_error() {
        let fparams = ZSTD_frameParameters {
            contentSizeFlag: 1,
            checksumFlag: 1,
            noDictIDFlag: 0,
        };
        let mut context = SetFParamsTestContext {
            set_result: ERROR(ZstdErrorCode::StageWrong),
            fail_at: 1,
            ..SetFParamsTestContext::default()
        };
        let state = set_fparams_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setFParams(&state, fparams) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.parameter_calls, [(ZSTD_C_CONTENT_SIZE_FLAG, 1)]);
    }

    #[test]
    fn set_fparams_propagates_a_later_parameter_error_without_following_updates() {
        let fparams = ZSTD_frameParameters {
            contentSizeFlag: 1,
            checksumFlag: 0,
            noDictIDFlag: 0,
        };
        let mut context = SetFParamsTestContext {
            set_result: ERROR(ZstdErrorCode::ParameterOutOfBound),
            fail_at: 2,
            ..SetFParamsTestContext::default()
        };
        let state = set_fparams_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setFParams(&state, fparams) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert_eq!(
            context.parameter_calls,
            [(ZSTD_C_CONTENT_SIZE_FLAG, 1), (ZSTD_C_CHECKSUM_FLAG, 0),]
        );
    }

    #[derive(Default)]
    struct SetParamsTestContext {
        events: Vec<&'static str>,
        received_cparams: Option<ZSTD_compressionParameters>,
        received_fparams: Option<ZSTD_frameParameters>,
        check_result: usize,
        f_params_result: usize,
        c_params_result: usize,
    }

    unsafe fn set_params_test_context(context: *mut c_void) -> &'static mut SetParamsTestContext {
        unsafe { &mut *context.cast::<SetParamsTestContext>() }
    }

    unsafe extern "C" fn set_params_test_check(
        context: *mut c_void,
        cparams: ZSTD_compressionParameters,
    ) -> usize {
        let context = unsafe { set_params_test_context(context) };
        context.events.push("check");
        context.received_cparams = Some(cparams);
        context.check_result
    }

    unsafe extern "C" fn set_params_test_set_f_params(
        context: *mut c_void,
        fparams: ZSTD_frameParameters,
    ) -> usize {
        let context = unsafe { set_params_test_context(context) };
        context.events.push("f-params");
        context.received_fparams = Some(fparams);
        context.f_params_result
    }

    unsafe extern "C" fn set_params_test_set_c_params(
        context: *mut c_void,
        cparams: ZSTD_compressionParameters,
    ) -> usize {
        let context = unsafe { set_params_test_context(context) };
        context.events.push("c-params");
        context.received_cparams = Some(cparams);
        context.c_params_result
    }

    fn set_params_test_state(context: &mut SetParamsTestContext) -> ZSTD_rust_setParamsState {
        ZSTD_rust_setParamsState {
            callback_context: (context as *mut SetParamsTestContext).cast(),
            check_c_params: set_params_test_check,
            set_f_params: set_params_test_set_f_params,
            set_c_params: set_params_test_set_c_params,
        }
    }

    fn set_params_test_params() -> ZSTD_parameters {
        ZSTD_parameters {
            cParams: ZSTD_compressionParameters {
                windowLog: 20,
                chainLog: 19,
                hashLog: 18,
                searchLog: 5,
                minMatch: 4,
                targetLength: 32,
                strategy: 3,
            },
            fParams: ZSTD_frameParameters {
                contentSizeFlag: 1,
                checksumFlag: 0,
                noDictIDFlag: 1,
            },
        }
    }

    #[test]
    fn set_params_preserves_check_frame_then_compression_order() {
        let params = set_params_test_params();
        let mut context = SetParamsTestContext::default();
        let state = set_params_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setParams(&state, params) };

        assert_eq!(result, 0);
        assert_eq!(context.events, ["check", "f-params", "c-params"]);
        assert_eq!(context.received_cparams, Some(params.cParams));
        assert_eq!(context.received_fparams, Some(params.fParams));
    }

    #[test]
    fn set_params_stops_before_frame_and_compression_after_check_error() {
        let params = set_params_test_params();
        let mut context = SetParamsTestContext {
            check_result: ERROR(ZstdErrorCode::ParameterOutOfBound),
            ..SetParamsTestContext::default()
        };
        let state = set_params_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setParams(&state, params) };

        assert_eq!(result, ERROR(ZstdErrorCode::ParameterOutOfBound));
        assert_eq!(context.events, ["check"]);
        assert!(context.received_fparams.is_none());
    }

    #[test]
    fn set_params_stops_before_compression_after_frame_error() {
        let params = set_params_test_params();
        let mut context = SetParamsTestContext {
            f_params_result: ERROR(ZstdErrorCode::StageWrong),
            ..SetParamsTestContext::default()
        };
        let state = set_params_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setParams(&state, params) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.events, ["check", "f-params"]);
        assert!(context.received_cparams.is_some());
    }

    #[test]
    fn set_params_propagates_compression_error_after_prior_stages() {
        let params = set_params_test_params();
        let mut context = SetParamsTestContext {
            c_params_result: ERROR(ZstdErrorCode::StageWrong),
            ..SetParamsTestContext::default()
        };
        let state = set_params_test_state(&mut context);

        let result = unsafe { ZSTD_rust_setParams(&state, params) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(context.events, ["check", "f-params", "c-params"]);
    }

    #[test]
    fn pledged_src_size_writes_the_init_stage_value_plus_one() {
        let mut pledged_src_size_plus_one = 0;

        let result = unsafe {
            ZSTD_rust_setPledgedSrcSize(
                ZSTD_CSTREAM_STAGE_INIT,
                123,
                &mut pledged_src_size_plus_one,
            )
        };

        assert_eq!(result, 0);
        assert_eq!(pledged_src_size_plus_one, 124);
    }

    #[test]
    fn pledged_src_size_wraps_at_u64_max() {
        let mut pledged_src_size_plus_one = 123;

        let result = unsafe {
            ZSTD_rust_setPledgedSrcSize(
                ZSTD_CSTREAM_STAGE_INIT,
                u64::MAX,
                &mut pledged_src_size_plus_one,
            )
        };

        assert_eq!(result, 0);
        assert_eq!(pledged_src_size_plus_one, 0);
    }

    #[test]
    fn pledged_src_size_rejects_non_init_stage_with_stage_wrong() {
        let mut pledged_src_size_plus_one = 123;

        let result = unsafe { ZSTD_rust_setPledgedSrcSize(1, 456, &mut pledged_src_size_plus_one) };

        assert_eq!(result, ERROR(ZstdErrorCode::StageWrong));
        assert_eq!(
            crate::errors::ERR_getErrorCode(result),
            ZstdErrorCode::StageWrong as i32
        );
        assert_eq!(pledged_src_size_plus_one, 123);
    }

    #[test]
    fn sizeof_local_dict_ignores_size_without_a_buffer() {
        assert_eq!(sizeof_local_dict(0, 37, 11), 11);
        assert_eq!(ZSTD_rust_sizeofLocalDict(0, 37, 11), 11);
    }

    #[test]
    fn sizeof_local_dict_adds_present_buffer_and_cdict_sizes() {
        assert_eq!(sizeof_local_dict(1, 37, 11), 48);
        assert_eq!(sizeof_local_dict(1, 0, 11), 11);
        assert_eq!(ZSTD_rust_sizeofLocalDict(1, 37, 11), 48);
    }

    #[test]
    fn sizeof_local_dict_wraps_like_c_size_t_addition() {
        assert_eq!(sizeof_local_dict(1, usize::MAX, 1), 0);
        assert_eq!(sizeof_local_dict(0, usize::MAX, usize::MAX), usize::MAX);
    }

    #[test]
    fn sizeof_cdict_handles_zero_components() {
        assert_eq!(sizeof_cdict(0, 0), 0);
        assert_eq!(ZSTD_rust_sizeofCDict(0, 0), 0);
    }

    #[test]
    fn sizeof_cdict_adds_components_in_order() {
        assert_eq!(sizeof_cdict(17, 25), 42);
        assert_eq!(ZSTD_rust_sizeofCDict(17, 25), 42);
    }

    #[test]
    fn sizeof_cdict_wraps_like_c_size_t_addition() {
        assert_eq!(sizeof_cdict(usize::MAX, 1), 0);
        assert_eq!(ZSTD_rust_sizeofCDict(usize::MAX, 1), 0);
    }

    #[test]
    fn sizeof_cctx_handles_zero_components() {
        assert_eq!(sizeof_cctx(0, 0, 0, 0), 0);
        assert_eq!(ZSTD_rust_sizeofCCtx(0, 0, 0, 0), 0);
    }

    #[test]
    fn sizeof_cctx_adds_components_in_order() {
        assert_eq!(sizeof_cctx(1, 2, 3, 4), 10);
        assert_eq!(ZSTD_rust_sizeofCCtx(1, 2, 3, 4), 10);
    }

    #[test]
    fn sizeof_cctx_wraps_like_c_size_t_addition() {
        assert_eq!(sizeof_cctx(usize::MAX, 1, 2, 3), 5);
        assert_eq!(ZSTD_rust_sizeofCCtx(usize::MAX, 1, 2, 3), 5);
    }

    #[test]
    fn estimate_workspace_size_handles_zero_components() {
        assert_eq!(estimate_workspace_size(0, 0, 0, 0, 0, 0, 0, 0, 0), 0);
        assert_eq!(
            ZSTD_rust_estimateWorkspaceSize(0, 0, 0, 0, 0, 0, 0, 0, 0),
            0
        );
    }

    #[test]
    fn estimate_workspace_size_adds_components_in_order() {
        assert_eq!(estimate_workspace_size(1, 2, 3, 4, 5, 6, 7, 8, 9), 45);
        assert_eq!(
            ZSTD_rust_estimateWorkspaceSize(1, 2, 3, 4, 5, 6, 7, 8, 9),
            45
        );
    }

    #[test]
    fn estimate_workspace_size_wraps_at_multiple_operand_positions() {
        assert_eq!(
            estimate_workspace_size(usize::MAX, 1, 0, 0, 0, 0, 0, 0, 0),
            0
        );
        assert_eq!(
            estimate_workspace_size(0, usize::MAX, 1, 0, 0, 0, 0, 0, 0),
            0
        );
        assert_eq!(
            estimate_workspace_size(0, 0, 0, 0, 0, usize::MAX, 1, 0, 0),
            0
        );
        assert_eq!(
            ZSTD_rust_estimateWorkspaceSize(0, 0, 0, 0, 0, 0, 0, usize::MAX, 1),
            0
        );
    }

    fn cctx_workspace_test_sizing() -> ZSTD_rustCCtxWorkspaceSizing {
        ZSTD_rustCCtxWorkspaceSizing {
            cctxSize: 32,
            compressedBlockStateSize: 24,
            seqDefSize: 8,
            rawSeqSize: 12,
            externalSequenceSize: 16,
            tmpWorkspaceSize: 64,
            wildcopyOverlength: 32,
            matchTSize: 4,
            optimalTSize: 8,
            asanRedzoneSize: 0,
        }
    }

    fn cctx_workspace_test_cparams() -> ZSTD_compressionParameters {
        ZSTD_compressionParameters {
            windowLog: 10,
            chainLog: 6,
            hashLog: 6,
            searchLog: 1,
            minMatch: 4,
            targetLength: 16,
            strategy: 3,
        }
    }

    fn cctx_workspace_test_estimate(
        sizing: &ZSTD_rustCCtxWorkspaceSizing,
        ldm_enable: c_int,
        ldm_hash_log: u32,
        ldm_bucket_size_log: u32,
        ldm_min_match_length: u32,
        is_static: c_int,
        buff_in_size: usize,
        buff_out_size: usize,
        use_sequence_producer: c_int,
    ) -> usize {
        unsafe {
            ZSTD_rust_estimateCCtxWorkspaceSize(
                cctx_workspace_test_cparams(),
                ldm_enable,
                ldm_hash_log,
                ldm_bucket_size_log,
                ldm_min_match_length,
                is_static,
                ZSTD_RUST_PS_DISABLE,
                buff_in_size,
                buff_out_size,
                1000,
                use_sequence_producer,
                0,
                sizing,
            )
        }
    }

    fn cctx_reset_test_state(
        sizing: &ZSTD_rustCCtxWorkspaceSizing,
        plan: &mut ZSTD_rustCCtxResetPlan,
        pledged_src_size: u64,
        max_block_size: usize,
        ldm_enable: c_int,
        ldm_min_match_length: u32,
        in_buffer_buffered: c_int,
        out_buffer_buffered: c_int,
        use_sequence_producer: c_int,
        initialized: c_int,
        index_too_close: c_int,
        dict_too_big: c_int,
    ) -> ZSTD_rustCCtxResetState {
        ZSTD_rustCCtxResetState {
            cParams: cctx_workspace_test_cparams(),
            ldmEnable: ldm_enable,
            ldmHashLog: 4,
            ldmBucketSizeLog: 2,
            ldmMinMatchLength: ldm_min_match_length,
            isStatic: 0,
            useRowMatchFinder: ZSTD_RUST_PS_DISABLE,
            inBufferBuffered: in_buffer_buffered,
            outBufferBuffered: out_buffer_buffered,
            useSequenceProducer: use_sequence_producer,
            initialized,
            indexTooClose: index_too_close,
            dictTooBig: dict_too_big,
            pledgedSrcSize: pledged_src_size,
            maxBlockSize: max_block_size,
            sizing,
            plan,
        }
    }

    #[test]
    fn cctx_reset_plan_computes_window_buffers_and_sequence_capacities() {
        let sizing = cctx_workspace_test_sizing();
        let mut plan = ZSTD_rustCCtxResetPlan::default();
        let state = cctx_reset_test_state(
            &sizing,
            &mut plan,
            1000,
            512,
            ZSTD_RUST_PS_DISABLE,
            0,
            1,
            1,
            1,
            1,
            0,
            0,
        );

        assert_eq!(unsafe { ZSTD_rust_planCCtxReset(&state) }, 0);
        assert_eq!(plan.windowSize, 1000);
        assert_eq!(plan.blockSize, 512);
        assert_eq!(plan.maxNbSeq, 512 / 3);
        assert_eq!(plan.buffInSize, 1000 + 512);
        assert_eq!(
            plan.buffOutSize,
            crate::zstd_compress_api::ZSTD_compressBound(512) + 1
        );
        assert_eq!(
            plan.maxNbExternalSeq,
            crate::zstd_compress_api::ZSTD_sequenceBound(512)
        );
        assert_eq!(plan.maxNbLdmSeq, 0);
        assert_eq!(plan.needsIndexReset, 0);
        assert!(!ERR_isError(plan.neededSpace));
        assert_ne!(plan.neededSpace, 0);
    }

    #[test]
    fn cctx_reset_plan_tracks_ldm_and_index_reset_policy() {
        let sizing = cctx_workspace_test_sizing();
        let mut plan = ZSTD_rustCCtxResetPlan::default();
        let mut state = cctx_reset_test_state(
            &sizing,
            &mut plan,
            u64::MAX,
            2048,
            ZSTD_RUST_PS_ENABLE,
            64,
            0,
            0,
            0,
            0,
            0,
            0,
        );

        assert_eq!(unsafe { ZSTD_rust_planCCtxReset(&state) }, 0);
        assert_eq!(plan.windowSize, 1 << 10);
        assert_eq!(plan.blockSize, 1 << 10);
        assert_eq!(plan.maxNbLdmSeq, (1 << 10) / 64);
        assert_eq!(plan.buffInSize, 0);
        assert_eq!(plan.buffOutSize, 0);
        assert_eq!(plan.needsIndexReset, 1);

        state.initialized = 1;
        state.indexTooClose = 1;
        assert_eq!(unsafe { ZSTD_rust_planCCtxReset(&state) }, 0);
        assert_eq!(plan.needsIndexReset, 1);

        state.indexTooClose = 0;
        state.dictTooBig = 1;
        assert_eq!(unsafe { ZSTD_rust_planCCtxReset(&state) }, 0);
        assert_eq!(plan.needsIndexReset, 1);
    }

    #[test]
    fn cctx_reset_plan_rejects_unadjusted_enabled_ldm() {
        let sizing = cctx_workspace_test_sizing();
        let mut plan = ZSTD_rustCCtxResetPlan::default();
        let state = cctx_reset_test_state(
            &sizing,
            &mut plan,
            1000,
            512,
            ZSTD_RUST_PS_ENABLE,
            0,
            0,
            0,
            0,
            1,
            0,
            0,
        );

        assert_eq!(
            unsafe { ZSTD_rust_planCCtxReset(&state) },
            ERROR(ZstdErrorCode::Generic)
        );
    }

    #[test]
    fn cctx_reset_policy_preserves_plan_workspace_tail_order() {
        let events = std::cell::RefCell::new(Vec::new());
        let result = run_cctx_reset_policy(
            || {
                events.borrow_mut().push("plan");
                0
            },
            || events.borrow_mut().push("prepare-workspace"),
            || {
                events.borrow_mut().push("workspace");
                0
            },
            || events.borrow_mut().push("prepare-tail"),
            || {
                events.borrow_mut().push("tail");
                0
            },
        );

        assert_eq!(result, 0);
        assert_eq!(
            events.into_inner(),
            [
                "plan",
                "prepare-workspace",
                "workspace",
                "prepare-tail",
                "tail"
            ]
        );
    }

    #[test]
    fn cctx_reset_policy_propagates_workspace_error_before_tail() {
        let events = std::cell::RefCell::new(Vec::new());
        let workspace_error = ERROR(ZstdErrorCode::MemoryAllocation);
        let result = run_cctx_reset_policy(
            || {
                events.borrow_mut().push("plan");
                0
            },
            || events.borrow_mut().push("prepare-workspace"),
            || {
                events.borrow_mut().push("workspace");
                workspace_error
            },
            || events.borrow_mut().push("prepare-tail"),
            || {
                events.borrow_mut().push("tail");
                0
            },
        );

        assert_eq!(result, workspace_error);
        assert_eq!(
            events.into_inner(),
            ["plan", "prepare-workspace", "workspace"]
        );
    }

    #[derive(Debug, PartialEq)]
    enum ResetCCtxStorageTestEvent {
        Reserve(c_int, usize),
        Pointer(c_int),
        Size(c_int, usize),
        Int(c_int, c_int),
        Zero(usize),
        WindowInit,
        ResetExternalSequences,
    }

    #[derive(Default)]
    struct ResetCCtxStorageTestContext {
        events: Vec<ResetCCtxStorageTestEvent>,
        reserve_count: usize,
        reserve_failure: bool,
    }

    unsafe fn reset_cctx_storage_test_context(
        context: *mut c_void,
    ) -> &'static mut ResetCCtxStorageTestContext {
        unsafe { &mut *context.cast::<ResetCCtxStorageTestContext>() }
    }

    unsafe extern "C" fn reset_cctx_storage_test_set_pointer(
        context: *mut c_void,
        kind: c_int,
        _pointer: *mut c_void,
    ) {
        let context = unsafe { reset_cctx_storage_test_context(context) };
        context
            .events
            .push(ResetCCtxStorageTestEvent::Pointer(kind));
    }

    unsafe extern "C" fn reset_cctx_storage_test_set_size(
        context: *mut c_void,
        kind: c_int,
        value: usize,
    ) {
        let context = unsafe { reset_cctx_storage_test_context(context) };
        context
            .events
            .push(ResetCCtxStorageTestEvent::Size(kind, value));
    }

    unsafe extern "C" fn reset_cctx_storage_test_set_int(
        context: *mut c_void,
        kind: c_int,
        value: c_int,
    ) {
        let context = unsafe { reset_cctx_storage_test_context(context) };
        context
            .events
            .push(ResetCCtxStorageTestEvent::Int(kind, value));
    }

    unsafe extern "C" fn reset_cctx_storage_test_reserve(
        context: *mut c_void,
        kind: c_int,
        size: usize,
    ) -> *mut c_void {
        let context = unsafe { reset_cctx_storage_test_context(context) };
        context
            .events
            .push(ResetCCtxStorageTestEvent::Reserve(kind, size));
        let pointer = (0x1000usize + context.reserve_count * 0x1000) as *mut c_void;
        context.reserve_count += 1;
        pointer
    }

    unsafe extern "C" fn reset_cctx_storage_test_reserve_failed(context: *mut c_void) -> c_int {
        let context = unsafe { reset_cctx_storage_test_context(context) };
        c_int::from(context.reserve_failure)
    }

    unsafe extern "C" fn reset_cctx_storage_test_zero(
        context: *mut c_void,
        _pointer: *mut c_void,
        size: usize,
    ) {
        let context = unsafe { reset_cctx_storage_test_context(context) };
        context.events.push(ResetCCtxStorageTestEvent::Zero(size));
    }

    unsafe extern "C" fn reset_cctx_storage_test_window_init(context: *mut c_void) {
        let context = unsafe { reset_cctx_storage_test_context(context) };
        context.events.push(ResetCCtxStorageTestEvent::WindowInit);
    }

    unsafe extern "C" fn reset_cctx_storage_test_reset_external_sequences(context: *mut c_void) {
        let context = unsafe { reset_cctx_storage_test_context(context) };
        context
            .events
            .push(ResetCCtxStorageTestEvent::ResetExternalSequences);
    }

    fn reset_cctx_storage_test_state(
        context: &mut ResetCCtxStorageTestContext,
        ldm_enable: c_int,
        has_ext_seq_prod: c_int,
        block_size: usize,
        max_nb_seq: usize,
        max_nb_ldm_seq: usize,
        max_nb_external_seq: usize,
        buff_in_size: usize,
        buff_out_size: usize,
    ) -> ZSTD_rust_resetCCtxStorageState {
        ZSTD_rust_resetCCtxStorageState {
            callbackContext: (context as *mut ResetCCtxStorageTestContext).cast(),
            ldmEnable: ldm_enable,
            hasExtSeqProd: has_ext_seq_prod,
            hashLog: 4,
            bucketSizeLog: 2,
            blockSize: block_size,
            maxNbSeq: max_nb_seq,
            maxNbLdmSeq: max_nb_ldm_seq,
            maxNbExternalSeq: max_nb_external_seq,
            buffInSize: buff_in_size,
            buffOutSize: buff_out_size,
            seqDefSize: size_of::<SeqDef>(),
            ldmEntrySize: 8,
            rawSeqSize: 12,
            externalSequenceSize: size_of::<ZSTD_Sequence>(),
            byteSize: 1,
            wildcopyOverlength: 8,
            bufferedPolicy: ZSTD_BM_BUFFERED,
            setPointer: Some(reset_cctx_storage_test_set_pointer),
            setSize: Some(reset_cctx_storage_test_set_size),
            setInt: Some(reset_cctx_storage_test_set_int),
            reserve: Some(reset_cctx_storage_test_reserve),
            reserveFailed: Some(reset_cctx_storage_test_reserve_failed),
            zero: Some(reset_cctx_storage_test_zero),
            windowInit: Some(reset_cctx_storage_test_window_init),
            resetExternalSequences: Some(reset_cctx_storage_test_reset_external_sequences),
        }
    }

    #[test]
    fn cctx_storage_preserves_ordinary_reservation_and_publication_order() {
        let mut context = ResetCCtxStorageTestContext::default();
        let state = reset_cctx_storage_test_state(
            &mut context,
            ZSTD_RUST_PS_DISABLE,
            0,
            128,
            4,
            0,
            0,
            0,
            0,
        );

        assert_eq!(unsafe { ZSTD_rust_resetCCtxStorage(&state) }, 0);
        assert_eq!(
            context.events,
            [
                ResetCCtxStorageTestEvent::Reserve(
                    RESET_CCTX_RESERVE_ALIGNED64,
                    4 * size_of::<SeqDef>()
                ),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_SEQ_START),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 136),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_LITERALS),
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_MAX_NB_LIT, 128),
                ResetCCtxStorageTestEvent::Int(RESET_CCTX_INT_BUFFERED_POLICY, ZSTD_BM_BUFFERED),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 0),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_INPUT_BUFFER),
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_INPUT_BUFFER, 0),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 0),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_OUTPUT_BUFFER),
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_OUTPUT_BUFFER, 0),
                ResetCCtxStorageTestEvent::ResetExternalSequences,
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_MAX_NB_SEQ, 4),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 4),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_LL_CODE),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 4),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_ML_CODE),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 4),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_OF_CODE),
                ResetCCtxStorageTestEvent::Int(RESET_CCTX_INT_INITIALIZED, 1),
            ]
        );
    }

    #[test]
    fn cctx_storage_preserves_ldm_and_external_sequence_order() {
        let mut context = ResetCCtxStorageTestContext::default();
        let state = reset_cctx_storage_test_state(
            &mut context,
            ZSTD_RUST_PS_ENABLE,
            1,
            128,
            4,
            2,
            3,
            17,
            19,
        );
        let external_size = 3 * size_of::<ZSTD_Sequence>();

        assert_eq!(unsafe { ZSTD_rust_resetCCtxStorage(&state) }, 0);
        assert_eq!(
            context.events,
            [
                ResetCCtxStorageTestEvent::Reserve(
                    RESET_CCTX_RESERVE_ALIGNED64,
                    4 * size_of::<SeqDef>()
                ),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_SEQ_START),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_ALIGNED64, 16 * 8),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_LDM_HASH),
                ResetCCtxStorageTestEvent::Zero(16 * 8),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_ALIGNED64, 2 * 12),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_LDM_SEQUENCES),
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_MAX_NB_LDM_SEQ, 2),
                ResetCCtxStorageTestEvent::WindowInit,
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_ALIGNED64, external_size),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_EXTERNAL_SEQUENCES),
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_EXTERNAL_SEQ_CAPACITY, 3),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 136),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_LITERALS),
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_MAX_NB_LIT, 128),
                ResetCCtxStorageTestEvent::Int(RESET_CCTX_INT_BUFFERED_POLICY, ZSTD_BM_BUFFERED),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 17),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_INPUT_BUFFER),
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_INPUT_BUFFER, 17),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 19),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_OUTPUT_BUFFER),
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_OUTPUT_BUFFER, 19),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 4),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_LDM_BUCKETS),
                ResetCCtxStorageTestEvent::Zero(4),
                ResetCCtxStorageTestEvent::ResetExternalSequences,
                ResetCCtxStorageTestEvent::Size(RESET_CCTX_SIZE_MAX_NB_SEQ, 4),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 4),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_LL_CODE),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 4),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_ML_CODE),
                ResetCCtxStorageTestEvent::Reserve(RESET_CCTX_RESERVE_BUFFER, 4),
                ResetCCtxStorageTestEvent::Pointer(RESET_CCTX_POINTER_OF_CODE),
                ResetCCtxStorageTestEvent::Int(RESET_CCTX_INT_INITIALIZED, 1),
            ]
        );
    }

    #[test]
    fn cctx_storage_propagates_reservation_failure_before_publication() {
        let mut context = ResetCCtxStorageTestContext {
            reserve_failure: true,
            ..ResetCCtxStorageTestContext::default()
        };
        let state = reset_cctx_storage_test_state(
            &mut context,
            ZSTD_RUST_PS_DISABLE,
            0,
            128,
            4,
            0,
            0,
            0,
            0,
        );

        assert_eq!(
            unsafe { ZSTD_rust_resetCCtxStorage(&state) },
            ERROR(ZstdErrorCode::MemoryAllocation)
        );
        assert_eq!(
            context.events,
            [ResetCCtxStorageTestEvent::Reserve(
                RESET_CCTX_RESERVE_ALIGNED64,
                4 * size_of::<SeqDef>()
            )]
        );
    }

    #[derive(Debug, PartialEq)]
    enum ResetCCtxWorkspaceTestEvent {
        BumpOversizedDuration,
        FreeWorkspace,
        CreateWorkspace(usize),
        ReserveObject(usize),
        Pointer(c_int),
        Size(c_int, usize),
        ClearWorkspace,
    }

    #[derive(Default)]
    struct ResetCCtxWorkspaceTestContext {
        events: Vec<ResetCCtxWorkspaceTestEvent>,
        reserve_count: usize,
        create_result: usize,
    }

    unsafe fn reset_cctx_workspace_test_context(
        context: *mut c_void,
    ) -> &'static mut ResetCCtxWorkspaceTestContext {
        unsafe { &mut *context.cast::<ResetCCtxWorkspaceTestContext>() }
    }

    unsafe extern "C" fn reset_cctx_workspace_test_bump(context: *mut c_void) {
        let context = unsafe { reset_cctx_workspace_test_context(context) };
        context
            .events
            .push(ResetCCtxWorkspaceTestEvent::BumpOversizedDuration);
    }

    unsafe extern "C" fn reset_cctx_workspace_test_free(context: *mut c_void) {
        let context = unsafe { reset_cctx_workspace_test_context(context) };
        context
            .events
            .push(ResetCCtxWorkspaceTestEvent::FreeWorkspace);
    }

    unsafe extern "C" fn reset_cctx_workspace_test_create(
        context: *mut c_void,
        needed_space: usize,
    ) -> usize {
        let context = unsafe { reset_cctx_workspace_test_context(context) };
        context
            .events
            .push(ResetCCtxWorkspaceTestEvent::CreateWorkspace(needed_space));
        context.create_result
    }

    unsafe extern "C" fn reset_cctx_workspace_test_reserve_object(
        context: *mut c_void,
        size: usize,
    ) -> *mut c_void {
        let context = unsafe { reset_cctx_workspace_test_context(context) };
        context
            .events
            .push(ResetCCtxWorkspaceTestEvent::ReserveObject(size));
        let pointer = (0x1000usize + context.reserve_count * 0x1000) as *mut c_void;
        context.reserve_count += 1;
        pointer
    }

    unsafe extern "C" fn reset_cctx_workspace_test_set_pointer(
        context: *mut c_void,
        kind: c_int,
        _pointer: *mut c_void,
    ) {
        let context = unsafe { reset_cctx_workspace_test_context(context) };
        context
            .events
            .push(ResetCCtxWorkspaceTestEvent::Pointer(kind));
    }

    unsafe extern "C" fn reset_cctx_workspace_test_set_size(
        context: *mut c_void,
        kind: c_int,
        value: usize,
    ) {
        let context = unsafe { reset_cctx_workspace_test_context(context) };
        context
            .events
            .push(ResetCCtxWorkspaceTestEvent::Size(kind, value));
    }

    unsafe extern "C" fn reset_cctx_workspace_test_clear(context: *mut c_void) {
        let context = unsafe { reset_cctx_workspace_test_context(context) };
        context
            .events
            .push(ResetCCtxWorkspaceTestEvent::ClearWorkspace);
    }

    fn reset_cctx_workspace_test_state(
        context: &mut ResetCCtxWorkspaceTestContext,
        is_static: c_int,
        workspace_too_small: c_int,
        workspace_wasteful: c_int,
        needed_space: usize,
        compressed_block_state_size: usize,
        tmp_workspace_size: usize,
        needs_index_reset: &mut c_int,
    ) -> ZSTD_rust_resetCCtxWorkspaceState {
        ZSTD_rust_resetCCtxWorkspaceState {
            callbackContext: (context as *mut ResetCCtxWorkspaceTestContext).cast(),
            isStatic: is_static,
            workspaceTooSmall: workspace_too_small,
            workspaceWasteful: workspace_wasteful,
            neededSpace: needed_space,
            compressedBlockStateSize: compressed_block_state_size,
            tmpWorkspaceSize: tmp_workspace_size,
            needsIndexReset: needs_index_reset,
            bumpOversizedDuration: Some(reset_cctx_workspace_test_bump),
            freeWorkspace: Some(reset_cctx_workspace_test_free),
            createWorkspace: Some(reset_cctx_workspace_test_create),
            reserveObject: Some(reset_cctx_workspace_test_reserve_object),
            setPointer: Some(reset_cctx_workspace_test_set_pointer),
            setSize: Some(reset_cctx_workspace_test_set_size),
            clearWorkspace: Some(reset_cctx_workspace_test_clear),
        }
    }

    #[test]
    fn cctx_workspace_preserves_existing_workspace_and_clear_order() {
        let mut context = ResetCCtxWorkspaceTestContext::default();
        let mut needs_index_reset = 0;
        let state = reset_cctx_workspace_test_state(
            &mut context,
            0,
            0,
            0,
            4096,
            128,
            64,
            &mut needs_index_reset,
        );

        assert_eq!(unsafe { ZSTD_rust_resetCCtxWorkspace(&state) }, 0);
        assert_eq!(needs_index_reset, 0);
        assert_eq!(
            context.events,
            [
                ResetCCtxWorkspaceTestEvent::BumpOversizedDuration,
                ResetCCtxWorkspaceTestEvent::ClearWorkspace,
            ]
        );
    }

    #[test]
    fn cctx_workspace_preserves_resize_reservation_and_publication_order() {
        let mut context = ResetCCtxWorkspaceTestContext::default();
        let mut needs_index_reset = 0;
        let state = reset_cctx_workspace_test_state(
            &mut context,
            0,
            1,
            0,
            4096,
            128,
            64,
            &mut needs_index_reset,
        );

        assert_eq!(unsafe { ZSTD_rust_resetCCtxWorkspace(&state) }, 0);
        assert_eq!(needs_index_reset, RESET_CCTX_INDEX_RESET);
        assert_eq!(
            context.events,
            [
                ResetCCtxWorkspaceTestEvent::BumpOversizedDuration,
                ResetCCtxWorkspaceTestEvent::FreeWorkspace,
                ResetCCtxWorkspaceTestEvent::CreateWorkspace(4096),
                ResetCCtxWorkspaceTestEvent::ReserveObject(128),
                ResetCCtxWorkspaceTestEvent::Pointer(RESET_CCTX_POINTER_PREV_CBLOCK),
                ResetCCtxWorkspaceTestEvent::ReserveObject(128),
                ResetCCtxWorkspaceTestEvent::Pointer(RESET_CCTX_POINTER_NEXT_CBLOCK),
                ResetCCtxWorkspaceTestEvent::ReserveObject(64),
                ResetCCtxWorkspaceTestEvent::Pointer(RESET_CCTX_POINTER_TMP_WORKSPACE),
                ResetCCtxWorkspaceTestEvent::Size(RESET_CCTX_SIZE_TMP_WORKSPACE, 64),
                ResetCCtxWorkspaceTestEvent::ClearWorkspace,
            ]
        );
    }

    #[test]
    fn cctx_workspace_rejects_static_resize_before_mutating_workspace() {
        let mut context = ResetCCtxWorkspaceTestContext::default();
        let mut needs_index_reset = 0;
        let state = reset_cctx_workspace_test_state(
            &mut context,
            1,
            1,
            0,
            4096,
            128,
            64,
            &mut needs_index_reset,
        );

        assert_eq!(
            unsafe { ZSTD_rust_resetCCtxWorkspace(&state) },
            ERROR(ZstdErrorCode::MemoryAllocation)
        );
        assert_eq!(needs_index_reset, 0);
        assert!(context.events.is_empty());
    }

    #[derive(Default)]
    struct ResetCCtxTailTestContext {
        events: Vec<&'static str>,
        match_result: usize,
        storage_result: usize,
    }

    unsafe fn reset_cctx_tail_test_context(
        context: *mut c_void,
    ) -> &'static mut ResetCCtxTailTestContext {
        unsafe { &mut *context.cast::<ResetCCtxTailTestContext>() }
    }

    unsafe extern "C" fn reset_cctx_tail_test_initialize(context: *mut c_void) {
        let context = unsafe { reset_cctx_tail_test_context(context) };
        context.events.push("initialize");
    }

    unsafe extern "C" fn reset_cctx_tail_test_reset_match_state(context: *mut c_void) -> usize {
        let context = unsafe { reset_cctx_tail_test_context(context) };
        context.events.push("reset-match-state");
        context.match_result
    }

    unsafe extern "C" fn reset_cctx_tail_test_reset_storage(context: *mut c_void) -> usize {
        let context = unsafe { reset_cctx_tail_test_context(context) };
        context.events.push("reset-storage");
        context.storage_result
    }

    fn reset_cctx_tail_test_state(
        context: &mut ResetCCtxTailTestContext,
        compressed_block_state: *mut ZSTD_compressedBlockState_t,
    ) -> ZSTD_rust_resetCCtxTailState {
        ZSTD_rust_resetCCtxTailState {
            callbackContext: (context as *mut ResetCCtxTailTestContext).cast(),
            initialize: Some(reset_cctx_tail_test_initialize),
            compressedBlockState: compressed_block_state,
            resetMatchState: Some(reset_cctx_tail_test_reset_match_state),
            resetStorage: Some(reset_cctx_tail_test_reset_storage),
        }
    }

    #[test]
    fn cctx_reset_tail_preserves_post_workspace_callback_order() {
        let mut context = ResetCCtxTailTestContext::default();
        let mut block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        let state = reset_cctx_tail_test_state(&mut context, &mut block_state);

        assert_eq!(unsafe { ZSTD_rust_resetCCtxTail(&state) }, 0);
        assert_eq!(
            context.events,
            ["initialize", "reset-match-state", "reset-storage"]
        );
        assert_eq!(block_state.rep, [1, 4, 8]);
        assert_eq!(block_state.entropy.huf.repeatMode, 0);
    }

    #[test]
    fn cctx_reset_tail_stops_before_storage_after_match_state_error() {
        let mut context = ResetCCtxTailTestContext {
            match_result: ERROR(ZstdErrorCode::StageWrong),
            ..ResetCCtxTailTestContext::default()
        };
        let mut block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        let state = reset_cctx_tail_test_state(&mut context, &mut block_state);

        assert_eq!(
            unsafe { ZSTD_rust_resetCCtxTail(&state) },
            ERROR(ZstdErrorCode::StageWrong)
        );
        assert_eq!(context.events, ["initialize", "reset-match-state"]);
    }

    #[test]
    fn cctx_reset_tail_propagates_storage_error_after_match_state() {
        let mut context = ResetCCtxTailTestContext {
            storage_result: ERROR(ZstdErrorCode::MemoryAllocation),
            ..ResetCCtxTailTestContext::default()
        };
        let mut block_state =
            unsafe { MaybeUninit::<ZSTD_compressedBlockState_t>::zeroed().assume_init() };
        let state = reset_cctx_tail_test_state(&mut context, &mut block_state);

        assert_eq!(
            unsafe { ZSTD_rust_resetCCtxTail(&state) },
            ERROR(ZstdErrorCode::MemoryAllocation)
        );
        assert_eq!(
            context.events,
            ["initialize", "reset-match-state", "reset-storage"]
        );
    }

    #[test]
    fn estimate_cctx_workspace_size_keeps_static_and_buffer_components_separate() {
        let sizing = cctx_workspace_test_sizing();
        let ordinary = cctx_workspace_test_estimate(&sizing, 0, 0, 0, 0, 0, 0, 0, 0);
        let static_context = cctx_workspace_test_estimate(&sizing, 0, 0, 0, 0, 1, 0, 0, 0);
        let buffered = cctx_workspace_test_estimate(&sizing, 0, 0, 0, 0, 0, 17, 23, 0);
        let external = cctx_workspace_test_estimate(&sizing, 0, 0, 0, 0, 0, 0, 0, 1);

        assert_eq!(static_context - ordinary, sizing.cctxSize);
        assert_eq!(buffered - ordinary, 17 + 23);
        assert_eq!(external - ordinary, 6265);
    }

    #[test]
    fn estimate_cctx_workspace_size_adds_ldm_table_and_sequence_space_only_when_enabled() {
        let sizing = cctx_workspace_test_sizing();
        let ordinary = cctx_workspace_test_estimate(&sizing, 0, 4, 2, 64, 0, 0, 0, 0);
        let ldm = cctx_workspace_test_estimate(&sizing, ZSTD_RUST_PS_ENABLE, 4, 2, 64, 0, 0, 0, 0);

        assert_eq!(ldm - ordinary, 324);
    }

    #[test]
    fn max_estimate_cctx_size_handles_zero_values() {
        assert_eq!(max_estimate_cctx_size(0, 0, 0, 0), 0);
        assert_eq!(ZSTD_rust_maxEstimateCCtxSize(0, 0, 0, 0), 0);
    }

    #[test]
    fn max_estimate_cctx_size_selects_the_largest_ordinary_value() {
        assert_eq!(max_estimate_cctx_size(17, 42, 9, 31), 42);
        assert_eq!(ZSTD_rust_maxEstimateCCtxSize(17, 42, 9, 31), 42);
    }

    #[test]
    fn max_estimate_cctx_size_preserves_equal_values() {
        assert_eq!(max_estimate_cctx_size(42, 42, 42, 42), 42);
        assert_eq!(ZSTD_rust_maxEstimateCCtxSize(42, 42, 42, 42), 42);
    }

    #[test]
    fn max_estimate_cctx_size_accepts_size_max() {
        assert_eq!(max_estimate_cctx_size(1, usize::MAX, 3, 2), usize::MAX);
        assert_eq!(
            ZSTD_rust_maxEstimateCCtxSize(1, usize::MAX, 3, 2),
            usize::MAX
        );
    }

    #[test]
    fn max_estimate_cctx_size_compares_error_like_raw_values() {
        let smaller_error = ERROR(ZstdErrorCode::DstSizeTooSmall);
        let larger_error = ERROR(ZstdErrorCode::ParameterUnsupported);

        assert_eq!(
            max_estimate_cctx_size(128, smaller_error, 256, larger_error),
            larger_error
        );
        assert_eq!(
            ZSTD_rust_maxEstimateCCtxSize(128, smaller_error, 256, larger_error),
            larger_error
        );
    }

    #[test]
    fn estimate_cctx_size_internal_preserves_tier_order_and_max_policy() {
        let mut context = EstimateCCtxSizeTestContext {
            compression_levels: Vec::new(),
            source_size_hints: Vec::new(),
            parameter_tiers: Vec::new(),
        };
        let state = ZSTD_rust_estimateCCtxSizeState {
            callback_context: (&mut context as *mut EstimateCCtxSizeTestContext).cast(),
            compression_level: 7,
            get_c_params: estimate_cctx_size_test_get_c_params,
            estimate: estimate_cctx_size_test_estimate,
        };

        assert_eq!(unsafe { ZSTD_rust_estimateCCtxSizeInternal(&state) }, 91);
        assert_eq!(context.compression_levels, vec![7; 4]);
        assert_eq!(
            context.source_size_hints,
            vec![16 * 1024, 128 * 1024, 256 * 1024, ZSTD_CONTENTSIZE_UNKNOWN]
        );
        assert_eq!(context.parameter_tiers, vec![1, 2, 3, 4]);
    }

    #[test]
    fn estimate_cctx_size_internal_rejects_a_null_state() {
        assert_eq!(
            unsafe { ZSTD_rust_estimateCCtxSizeInternal(ptr::null()) },
            ERROR(ZstdErrorCode::Generic)
        );
    }

    #[test]
    fn public_one_shot_abi_is_c_compatible() {
        let entry: unsafe extern "C" fn(*mut c_void, usize, *const c_void, usize, c_int) -> usize =
            ZSTD_compress;
        let context_entry: unsafe extern "C" fn(
            *mut c_void,
            *mut c_void,
            usize,
            *const c_void,
            usize,
            c_int,
        ) -> usize = ZSTD_compressCCtx;
        assert_eq!(size_of::<usize>(), size_of::<*const c_void>());
        let _ = entry;
        let _ = context_entry;
    }

    #[test]
    fn explicit_context_simple_api_matches_one_shot_path() {
        let input = b"explicit context compression remains a simple API";
        let capacity = crate::zstd_compress_api::ZSTD_compressBound(input.len());
        let mut output = vec![0u8; capacity];
        let written = unsafe {
            ZSTD_compressCCtx(
                std::ptr::dangling_mut::<c_void>(),
                output.as_mut_ptr().cast(),
                output.len(),
                input.as_ptr().cast(),
                input.len(),
                3,
            )
        };
        assert!(!ERR_isError(written));
        output.truncate(written);
        let one_shot = compress_input(input, 3);
        assert_eq!(output, one_shot);
        if let Some(restored) = system_round_trip(&output) {
            assert_eq!(restored, input);
        }
    }

    #[test]
    fn one_shot_round_trip_across_block_boundaries() {
        let mut input = Vec::with_capacity(128 * 1024 + 37);
        for index in 0..(128 * 1024 + 37) {
            input.push(((index * 17) ^ (index / 31)) as u8);
        }

        let compressed = compress_input(&input, 3);
        if let Some(restored) = system_round_trip(&compressed) {
            assert_eq!(restored, input);
        }
    }

    #[test]
    fn empty_and_short_inputs_have_valid_frames() {
        for input in [b"".as_slice(), b"a", b"abcdefg", b"abcdefgh"] {
            let compressed = compress_input(input, 1);
            if let Some(restored) = system_round_trip(&compressed) {
                assert_eq!(restored, input);
            }
        }
    }

    #[test]
    fn one_shot_promotes_nonfirst_rle_blocks() {
        let mut input = vec![b'B'; 256 * 1024 - 2];
        input.extend(std::iter::repeat_n(b'A', 100 * 1024));

        let compressed = compress_input(&input, 1);
        assert!(compressed.len() <= 46);
        if let Some(restored) = system_round_trip(&compressed) {
            assert_eq!(restored, input);
        }
    }

    #[test]
    fn public_error_paths_match_size_t_error_contract() {
        let mut output = [0u8; 64];
        let source = [1u8; 8];
        assert_eq!(
            unsafe {
                ZSTD_compress(
                    output.as_mut_ptr().cast(),
                    0,
                    source.as_ptr().cast(),
                    source.len(),
                    3,
                )
            },
            ERROR(ZstdErrorCode::DstSizeTooSmall)
        );
        assert_eq!(
            unsafe { ZSTD_compress(ptr::null_mut(), 1, source.as_ptr().cast(), source.len(), 3) },
            ERROR(ZstdErrorCode::DstBufferNull)
        );
        assert_eq!(
            unsafe { ZSTD_compress(output.as_mut_ptr().cast(), output.len(), ptr::null(), 1, 3) },
            ERROR(ZstdErrorCode::SrcSizeWrong)
        );
    }
}