feat(rust): port compression-parameter selection

Move the context-free compression-parameter logic of zstd_compress.c to
rust/src/zstd_compress_params.rs: the compression-level tables (formerly
clevels.h), parameter bounds/checking/clamping, cycle log, level-table
selection, source/dictionary parameter adjustment, default frame
parameters, and the match-state/CDict size estimators.

The boundary follows the module's design notes: Rust owns only leaves
whose behavior is independent of C preprocessor configuration.  C keeps
the public ZSTD_* symbols and feeds the leaves everything that is
configuration-owned as explicit scalars:

- The ZSTD_EXCLUDE_*_BLOCK_COMPRESSOR strategy cascade stays in
  ZSTD_adjustCParams_internal() ahead of the Rust adjustment leaf, so
  reduced builds keep their fallback policy.
- Workspace estimation receives struct sizes (ZSTD_CDict, ZSTD_match_t,
  ZSTD_optimal_t), HUF workspace size, and the sanitizer redzone size,
  because those depend on private layouts and ASAN configuration.
- ZSTD_cParam_getBounds() forwards only the compression level and the
  seven core parameters; all other parameter bounds remain C.
- Frozen private constants the leaves hardcode (short-cache and row-hash
  tag widths, MaxML/MaxLL/MaxOff/Litbits, ZSTD_OPT_SIZE, cwksp alignment)
  are pinned by ZSTD_STATIC_ASSERTs at the C call sites.

Two latent 32-bit bugs in the previously unwired module were fixed
before integration: dictAndWindowLog's max window size and the
window-resize threshold were hardcoded to the 64-bit constants
(1<<31, 1<<30) instead of deriving from ZSTD_WINDOWLOG_MAX, which is
30 on 32-bit targets.

clevels.h is no longer included anywhere but stays in-tree as the
reference for mechanical comparison against the Rust table.

Test plan:
- cd rust && cargo fmt --check && cargo clippy --all-targets -- -D
  warnings && cargo test --all-targets (125 tests)
- make -C tests fuzzer && ./tests/fuzzer -i1 --no-big-tests
- make -C tests test-rust-lib-smoke
- Byte-identity: zstd CLI frames for COPYING, a 250 KB C source, and a
  5 MB datagen sample at levels 1/3/9/19/--fast=5 are identical between
  this change and its parent commit.
This commit is contained in:
2026-07-11 09:32:49 +02:00
parent 959e485201
commit 529cd297e2
4 changed files with 1162 additions and 271 deletions
+6
View File
@@ -34,6 +34,12 @@ zstd ABI:
- `zstd_compress_frame` serializes frame headers, skippable frames, and the
last empty block; it takes scalar frame parameters so the C-owned
`ZSTD_CCtx_params` layout never crosses the language boundary.
- `zstd_compress_params` owns the compression-level tables (formerly
`clevels.h`), parameter bounds, clamping, validation, table selection,
source/dictionary adjustment, and match-state/CDict size estimation.
The C integration layer keeps the public `ZSTD_*` symbols and feeds the
leaves configuration-owned scalars: the excluded-block-compressor
strategy cascade, struct sizes, and sanitizer redzone policy.
- `zstd_fast` and `zstd_double_fast` implement the single- and two-table
fast block match finders, including attached and external dictionary paths.
- `zstd_lazy` implements greedy, lazy, lazy2, and binary-tree matching,
+2
View File
@@ -28,6 +28,8 @@ pub mod zstd_compress_frame;
#[cfg(feature = "compression")]
pub mod zstd_compress_literals;
#[cfg(feature = "compression")]
pub mod zstd_compress_params;
#[cfg(feature = "compression")]
pub mod zstd_compress_sequences;
#[cfg(feature = "compression")]
pub mod zstd_compress_superblock;
+1048
View File
@@ -0,0 +1,1048 @@
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
#![allow(clippy::missing_safety_doc)]
#![allow(clippy::too_many_arguments)]
//! Context-free compression-parameter selection and sizing leaves.
//!
//! This module deliberately does **not** own the public `ZSTD_*` symbols yet.
//! `zstd_compress.c` still owns configuration-sensitive policy: excluded block
//! compressors, private `ZSTD_CCtx_params` layouts, LDM workspace sizing, and
//! ASAN workspace policy. The C integration layer can select a raw table
//! entry here, apply its configured strategy cascade, then use the adjustment
//! and sizing leaves below. That keeps the Rust implementation independent of
//! C preprocessor state while retaining byte-for-byte C policy for reduced
//! builds.
use crate::errors::{ZstdErrorCode, ERROR};
use std::mem::size_of;
use std::os::raw::c_int;
pub const ZSTD_CONTENTSIZE_UNKNOWN: u64 = u64::MAX;
const ZSTD_CLEVEL_DEFAULT: c_int = 3;
const ZSTD_MAX_CLEVEL: c_int = 22;
const ZSTD_TARGETLENGTH_MAX: c_int = 1 << 17;
const ZSTD_BLOCKSIZE_MAX: usize = 1 << 17;
const ZSTD_WINDOWLOG_MIN: c_int = 10;
#[cfg(target_pointer_width = "32")]
const ZSTD_WINDOWLOG_MAX: c_int = 30;
#[cfg(not(target_pointer_width = "32"))]
const ZSTD_WINDOWLOG_MAX: c_int = 31;
const ZSTD_HASHLOG_MIN: c_int = 6;
const ZSTD_HASHLOG_MAX: c_int = 30;
const ZSTD_CHAINLOG_MIN: c_int = ZSTD_HASHLOG_MIN;
#[cfg(target_pointer_width = "32")]
const ZSTD_CHAINLOG_MAX: c_int = 29;
#[cfg(not(target_pointer_width = "32"))]
const ZSTD_CHAINLOG_MAX: c_int = 30;
const ZSTD_SEARCHLOG_MIN: c_int = 1;
const ZSTD_SEARCHLOG_MAX: c_int = ZSTD_WINDOWLOG_MAX - 1;
const ZSTD_MINMATCH_MIN: c_int = 3;
const ZSTD_MINMATCH_MAX: c_int = 7;
const ZSTD_TARGETLENGTH_MIN: c_int = 0;
const ZSTD_FAST: c_int = 1;
const ZSTD_DFAST: c_int = 2;
const ZSTD_GREEDY: c_int = 3;
const ZSTD_LAZY: c_int = 4;
const ZSTD_LAZY2: c_int = 5;
const ZSTD_BTLAZY2: c_int = 6;
const ZSTD_BTOPT: c_int = 7;
const ZSTD_BTULTRA: c_int = 8;
const ZSTD_BTULTRA2: c_int = 9;
const ZSTD_C_COMPRESSION_LEVEL: c_int = 100;
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;
/// Private compression-parameter modes from `zstd_compress_internal.h`.
///
/// They are ABI-compatible with `ZSTD_CParamMode_e` and intentionally kept as
/// integer constants because that enum remains private C API for now.
pub const ZSTD_RUST_CPM_NO_ATTACH_DICT: c_int = 0;
pub const ZSTD_RUST_CPM_ATTACH_DICT: c_int = 1;
pub const ZSTD_RUST_CPM_CREATE_CDICT: c_int = 2;
pub const ZSTD_RUST_CPM_UNKNOWN: c_int = 3;
/// `ZSTD_ParamSwitch_e` values used by the adjustment and sizing leaves.
pub const ZSTD_RUST_PS_AUTO: c_int = 0;
pub const ZSTD_RUST_PS_ENABLE: c_int = 1;
pub const ZSTD_RUST_PS_DISABLE: c_int = 2;
/// ABI-compatible `ZSTD_compressionParameters` from `zstd.h`.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_compressionParameters {
pub windowLog: u32,
pub chainLog: u32,
pub hashLog: u32,
pub searchLog: u32,
pub minMatch: u32,
pub targetLength: u32,
pub strategy: c_int,
}
/// ABI-compatible `ZSTD_frameParameters` from `zstd.h`.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_frameParameters {
pub contentSizeFlag: c_int,
pub checksumFlag: c_int,
pub noDictIDFlag: c_int,
}
/// ABI-compatible `ZSTD_parameters` from `zstd.h`.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_parameters {
pub cParams: ZSTD_compressionParameters,
pub fParams: ZSTD_frameParameters,
}
/// ABI-compatible `ZSTD_bounds` from `zstd.h`.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTD_bounds {
pub error: usize,
pub lowerBound: c_int,
pub upperBound: c_int,
}
/* `clevels.h`, represented as raw fields so the table stays compact and easy
* to compare mechanically against its C source. Field order is W, C, H, S,
* L, TL, strategy. */
const DEFAULT_CPARAMS: [[[u32; 7]; 23]; 4] = [
[
[19, 12, 13, 1, 6, 1, ZSTD_FAST as u32],
[19, 13, 14, 1, 7, 0, ZSTD_FAST as u32],
[20, 15, 16, 1, 6, 0, ZSTD_FAST as u32],
[21, 16, 17, 1, 5, 0, ZSTD_DFAST as u32],
[21, 18, 18, 1, 5, 0, ZSTD_DFAST as u32],
[21, 18, 19, 3, 5, 2, ZSTD_GREEDY as u32],
[21, 18, 19, 3, 5, 4, ZSTD_LAZY as u32],
[21, 19, 20, 4, 5, 8, ZSTD_LAZY as u32],
[21, 19, 20, 4, 5, 16, ZSTD_LAZY2 as u32],
[22, 20, 21, 4, 5, 16, ZSTD_LAZY2 as u32],
[22, 21, 22, 5, 5, 16, ZSTD_LAZY2 as u32],
[22, 21, 22, 6, 5, 16, ZSTD_LAZY2 as u32],
[22, 22, 23, 6, 5, 32, ZSTD_LAZY2 as u32],
[22, 22, 22, 4, 5, 32, ZSTD_BTLAZY2 as u32],
[22, 22, 23, 5, 5, 32, ZSTD_BTLAZY2 as u32],
[22, 23, 23, 6, 5, 32, ZSTD_BTLAZY2 as u32],
[22, 22, 22, 5, 5, 48, ZSTD_BTOPT as u32],
[23, 23, 22, 5, 4, 64, ZSTD_BTOPT as u32],
[23, 23, 22, 6, 3, 64, ZSTD_BTULTRA as u32],
[23, 24, 22, 7, 3, 256, ZSTD_BTULTRA2 as u32],
[25, 25, 23, 7, 3, 256, ZSTD_BTULTRA2 as u32],
[26, 26, 24, 7, 3, 512, ZSTD_BTULTRA2 as u32],
[27, 27, 25, 9, 3, 999, ZSTD_BTULTRA2 as u32],
],
[
[18, 12, 13, 1, 5, 1, ZSTD_FAST as u32],
[18, 13, 14, 1, 6, 0, ZSTD_FAST as u32],
[18, 14, 14, 1, 5, 0, ZSTD_DFAST as u32],
[18, 16, 16, 1, 4, 0, ZSTD_DFAST as u32],
[18, 16, 17, 3, 5, 2, ZSTD_GREEDY as u32],
[18, 17, 18, 5, 5, 2, ZSTD_GREEDY as u32],
[18, 18, 19, 3, 5, 4, ZSTD_LAZY as u32],
[18, 18, 19, 4, 4, 4, ZSTD_LAZY as u32],
[18, 18, 19, 4, 4, 8, ZSTD_LAZY2 as u32],
[18, 18, 19, 5, 4, 8, ZSTD_LAZY2 as u32],
[18, 18, 19, 6, 4, 8, ZSTD_LAZY2 as u32],
[18, 18, 19, 5, 4, 12, ZSTD_BTLAZY2 as u32],
[18, 19, 19, 7, 4, 12, ZSTD_BTLAZY2 as u32],
[18, 18, 19, 4, 4, 16, ZSTD_BTOPT as u32],
[18, 18, 19, 4, 3, 32, ZSTD_BTOPT as u32],
[18, 18, 19, 6, 3, 128, ZSTD_BTOPT as u32],
[18, 19, 19, 6, 3, 128, ZSTD_BTULTRA as u32],
[18, 19, 19, 8, 3, 256, ZSTD_BTULTRA as u32],
[18, 19, 19, 6, 3, 128, ZSTD_BTULTRA2 as u32],
[18, 19, 19, 8, 3, 256, ZSTD_BTULTRA2 as u32],
[18, 19, 19, 10, 3, 512, ZSTD_BTULTRA2 as u32],
[18, 19, 19, 12, 3, 512, ZSTD_BTULTRA2 as u32],
[18, 19, 19, 13, 3, 999, ZSTD_BTULTRA2 as u32],
],
[
[17, 12, 12, 1, 5, 1, ZSTD_FAST as u32],
[17, 12, 13, 1, 6, 0, ZSTD_FAST as u32],
[17, 13, 15, 1, 5, 0, ZSTD_FAST as u32],
[17, 15, 16, 2, 5, 0, ZSTD_DFAST as u32],
[17, 17, 17, 2, 4, 0, ZSTD_DFAST as u32],
[17, 16, 17, 3, 4, 2, ZSTD_GREEDY as u32],
[17, 16, 17, 3, 4, 4, ZSTD_LAZY as u32],
[17, 16, 17, 3, 4, 8, ZSTD_LAZY2 as u32],
[17, 16, 17, 4, 4, 8, ZSTD_LAZY2 as u32],
[17, 16, 17, 5, 4, 8, ZSTD_LAZY2 as u32],
[17, 16, 17, 6, 4, 8, ZSTD_LAZY2 as u32],
[17, 17, 17, 5, 4, 8, ZSTD_BTLAZY2 as u32],
[17, 18, 17, 7, 4, 12, ZSTD_BTLAZY2 as u32],
[17, 18, 17, 3, 4, 12, ZSTD_BTOPT as u32],
[17, 18, 17, 4, 3, 32, ZSTD_BTOPT as u32],
[17, 18, 17, 6, 3, 256, ZSTD_BTOPT as u32],
[17, 18, 17, 6, 3, 128, ZSTD_BTULTRA as u32],
[17, 18, 17, 8, 3, 256, ZSTD_BTULTRA as u32],
[17, 18, 17, 10, 3, 512, ZSTD_BTULTRA as u32],
[17, 18, 17, 5, 3, 256, ZSTD_BTULTRA2 as u32],
[17, 18, 17, 7, 3, 512, ZSTD_BTULTRA2 as u32],
[17, 18, 17, 9, 3, 512, ZSTD_BTULTRA2 as u32],
[17, 18, 17, 11, 3, 999, ZSTD_BTULTRA2 as u32],
],
[
[14, 12, 13, 1, 5, 1, ZSTD_FAST as u32],
[14, 14, 15, 1, 5, 0, ZSTD_FAST as u32],
[14, 14, 15, 1, 4, 0, ZSTD_FAST as u32],
[14, 14, 15, 2, 4, 0, ZSTD_DFAST as u32],
[14, 14, 14, 4, 4, 2, ZSTD_GREEDY as u32],
[14, 14, 14, 3, 4, 4, ZSTD_LAZY as u32],
[14, 14, 14, 4, 4, 8, ZSTD_LAZY2 as u32],
[14, 14, 14, 6, 4, 8, ZSTD_LAZY2 as u32],
[14, 14, 14, 8, 4, 8, ZSTD_LAZY2 as u32],
[14, 15, 14, 5, 4, 8, ZSTD_BTLAZY2 as u32],
[14, 15, 14, 9, 4, 8, ZSTD_BTLAZY2 as u32],
[14, 15, 14, 3, 4, 12, ZSTD_BTOPT as u32],
[14, 15, 14, 4, 3, 24, ZSTD_BTOPT as u32],
[14, 15, 14, 5, 3, 32, ZSTD_BTULTRA as u32],
[14, 15, 15, 6, 3, 64, ZSTD_BTULTRA as u32],
[14, 15, 15, 7, 3, 256, ZSTD_BTULTRA as u32],
[14, 15, 15, 5, 3, 48, ZSTD_BTULTRA2 as u32],
[14, 15, 15, 6, 3, 128, ZSTD_BTULTRA2 as u32],
[14, 15, 15, 7, 3, 256, ZSTD_BTULTRA2 as u32],
[14, 15, 15, 8, 3, 256, ZSTD_BTULTRA2 as u32],
[14, 15, 15, 8, 3, 512, ZSTD_BTULTRA2 as u32],
[14, 15, 15, 9, 3, 512, ZSTD_BTULTRA2 as u32],
[14, 15, 15, 10, 3, 999, ZSTD_BTULTRA2 as u32],
],
];
#[inline]
fn cparams_from_row(row: [u32; 7]) -> ZSTD_compressionParameters {
ZSTD_compressionParameters {
windowLog: row[0],
chainLog: row[1],
hashLog: row[2],
searchLog: row[3],
minMatch: row[4],
targetLength: row[5],
strategy: row[6] as c_int,
}
}
#[inline]
fn bounds(param: c_int) -> ZSTD_bounds {
let (lowerBound, upperBound) = match param {
ZSTD_C_COMPRESSION_LEVEL => (ZSTD_rust_params_minCLevel(), ZSTD_rust_params_maxCLevel()),
ZSTD_C_WINDOW_LOG => (ZSTD_WINDOWLOG_MIN, ZSTD_WINDOWLOG_MAX),
ZSTD_C_HASH_LOG => (ZSTD_HASHLOG_MIN, ZSTD_HASHLOG_MAX),
ZSTD_C_CHAIN_LOG => (ZSTD_CHAINLOG_MIN, ZSTD_CHAINLOG_MAX),
ZSTD_C_SEARCH_LOG => (ZSTD_SEARCHLOG_MIN, ZSTD_SEARCHLOG_MAX),
ZSTD_C_MIN_MATCH => (ZSTD_MINMATCH_MIN, ZSTD_MINMATCH_MAX),
ZSTD_C_TARGET_LENGTH => (ZSTD_TARGETLENGTH_MIN, ZSTD_TARGETLENGTH_MAX),
ZSTD_C_STRATEGY => (ZSTD_FAST, ZSTD_BTULTRA2),
_ => {
return ZSTD_bounds {
error: ERROR(ZstdErrorCode::ParameterUnsupported),
lowerBound: 0,
upperBound: 0,
}
}
};
ZSTD_bounds {
error: 0,
lowerBound,
upperBound,
}
}
#[inline]
fn within_bounds(param: c_int, value: c_int) -> bool {
let bounds = bounds(param);
bounds.error == 0 && value >= bounds.lowerBound && value <= bounds.upperBound
}
#[inline]
fn clamp_unsigned(value: u32, param: c_int) -> u32 {
let bounds = bounds(param);
debug_assert_eq!(bounds.error, 0);
let signed = value as c_int;
if signed < bounds.lowerBound {
bounds.lowerBound as u32
} else if signed > bounds.upperBound {
bounds.upperBound as u32
} else {
value
}
}
#[inline]
fn clamp_cparams(mut cparams: ZSTD_compressionParameters) -> ZSTD_compressionParameters {
cparams.windowLog = clamp_unsigned(cparams.windowLog, ZSTD_C_WINDOW_LOG);
cparams.chainLog = clamp_unsigned(cparams.chainLog, ZSTD_C_CHAIN_LOG);
cparams.hashLog = clamp_unsigned(cparams.hashLog, ZSTD_C_HASH_LOG);
cparams.searchLog = clamp_unsigned(cparams.searchLog, ZSTD_C_SEARCH_LOG);
cparams.minMatch = clamp_unsigned(cparams.minMatch, ZSTD_C_MIN_MATCH);
cparams.targetLength = clamp_unsigned(cparams.targetLength, ZSTD_C_TARGET_LENGTH);
let strategy_bounds = bounds(ZSTD_C_STRATEGY);
if cparams.strategy < strategy_bounds.lowerBound {
cparams.strategy = strategy_bounds.lowerBound;
} else if cparams.strategy > strategy_bounds.upperBound {
cparams.strategy = strategy_bounds.upperBound;
}
cparams
}
#[inline]
fn highbit32(value: u32) -> u32 {
debug_assert_ne!(value, 0);
u32::BITS - 1 - value.leading_zeros()
}
#[inline]
fn cycle_log(hash_log: u32, strategy: c_int) -> u32 {
hash_log.wrapping_sub((strategy >= ZSTD_BTLAZY2) as u32)
}
#[inline]
fn strategy_supports_row_match_finder(strategy: c_int) -> bool {
(ZSTD_GREEDY..=ZSTD_LAZY2).contains(&strategy)
}
#[inline]
fn row_match_finder_used(strategy: c_int, mode: c_int) -> bool {
debug_assert_ne!(mode, ZSTD_RUST_PS_AUTO);
strategy_supports_row_match_finder(strategy) && mode == ZSTD_RUST_PS_ENABLE
}
#[inline]
fn resolve_row_match_finder(mode: c_int, cparams: ZSTD_compressionParameters) -> c_int {
if mode != ZSTD_RUST_PS_AUTO {
return mode;
}
if strategy_supports_row_match_finder(cparams.strategy) && cparams.windowLog > 14 {
ZSTD_RUST_PS_ENABLE
} else {
ZSTD_RUST_PS_DISABLE
}
}
#[inline]
fn dict_and_window_log(window_log: u32, src_size: u64, dict_size: u64) -> u32 {
/* 1ULL << ZSTD_WINDOWLOG_MAX, which is smaller for 32-bit builds. */
const MAX_WINDOW_SIZE: u64 = 1u64 << ZSTD_WINDOWLOG_MAX;
if dict_size == 0 {
return window_log;
}
debug_assert!(window_log <= ZSTD_WINDOWLOG_MAX as u32);
debug_assert_ne!(src_size, ZSTD_CONTENTSIZE_UNKNOWN);
let window_size = 1u64 << window_log;
if window_size >= dict_size.wrapping_add(src_size) {
window_log
} else {
let dict_and_window_size = dict_size.wrapping_add(window_size);
if dict_and_window_size >= MAX_WINDOW_SIZE {
ZSTD_WINDOWLOG_MAX as u32
} else {
highbit32((dict_and_window_size as u32).wrapping_sub(1)) + 1
}
}
}
/// Adjusts a *validated, configuration-resolved* parameter set.
///
/// This is the direct Rust leaf for `ZSTD_adjustCParams_internal()` after the
/// C wrapper has applied its `ZSTD_EXCLUDE_*_BLOCK_COMPRESSOR` cascade. In
/// particular, it does not select a fallback strategy itself. `srcSize == 0`
/// means a known empty input here, just as it does in the C internal helper;
/// the public C wrapper must translate zero to `ZSTD_CONTENTSIZE_UNKNOWN`.
fn adjust_cparams(
mut cparams: ZSTD_compressionParameters,
mut src_size: u64,
mut dict_size: usize,
mode: c_int,
mut use_row_match_finder: c_int,
) -> ZSTD_compressionParameters {
debug_assert_eq!(check_cparams(cparams), 0);
const MIN_SRC_SIZE: u64 = 513;
/* 1ULL << (ZSTD_WINDOWLOG_MAX - 1), which is smaller for 32-bit builds. */
const MAX_WINDOW_RESIZE: u64 = 1u64 << (ZSTD_WINDOWLOG_MAX - 1);
match mode {
ZSTD_RUST_CPM_UNKNOWN | ZSTD_RUST_CPM_NO_ATTACH_DICT => {}
ZSTD_RUST_CPM_CREATE_CDICT => {
if dict_size != 0 && src_size == ZSTD_CONTENTSIZE_UNKNOWN {
src_size = MIN_SRC_SIZE;
}
}
ZSTD_RUST_CPM_ATTACH_DICT => dict_size = 0,
_ => debug_assert!(false, "invalid ZSTD_CParamMode_e"),
}
if src_size <= MAX_WINDOW_RESIZE && (dict_size as u64) <= MAX_WINDOW_RESIZE {
let total_size = src_size.wrapping_add(dict_size as u64) as u32;
let hash_size_min = 1u32 << ZSTD_HASHLOG_MIN;
let src_log = if total_size < hash_size_min {
ZSTD_HASHLOG_MIN as u32
} else {
highbit32(total_size.wrapping_sub(1)) + 1
};
cparams.windowLog = cparams.windowLog.min(src_log);
}
if src_size != ZSTD_CONTENTSIZE_UNKNOWN {
let dict_and_window_log =
dict_and_window_log(cparams.windowLog, src_size, dict_size as u64);
let cycle_log = cycle_log(cparams.chainLog, cparams.strategy);
cparams.hashLog = cparams.hashLog.min(dict_and_window_log + 1);
if cycle_log > dict_and_window_log {
cparams.chainLog = cparams
.chainLog
.wrapping_sub(cycle_log - dict_and_window_log);
}
}
cparams.windowLog = cparams.windowLog.max(ZSTD_WINDOWLOG_MIN as u32);
/* The short-cache tags used for fast and dfast CDicts consume eight bits
* of each 32-bit index. This is a fixed private-header constant today;
* if it becomes configurable, the C shim must pass it as an explicit
* adjustment input rather than silently changing this leaf. */
if mode == ZSTD_RUST_CPM_CREATE_CDICT
&& (cparams.strategy == ZSTD_FAST || cparams.strategy == ZSTD_DFAST)
{
const SHORT_CACHE_TAG_BITS: u32 = 8;
let max_short_cache_hash_log = 32 - SHORT_CACHE_TAG_BITS;
cparams.hashLog = cparams.hashLog.min(max_short_cache_hash_log);
cparams.chainLog = cparams.chainLog.min(max_short_cache_hash_log);
}
if use_row_match_finder == ZSTD_RUST_PS_AUTO {
use_row_match_finder = ZSTD_RUST_PS_ENABLE;
}
if row_match_finder_used(cparams.strategy, use_row_match_finder) {
const ROW_HASH_TAG_BITS: u32 = 8;
let row_log = cparams.searchLog.clamp(4, 6);
let max_hash_log = (32 - ROW_HASH_TAG_BITS) + row_log;
debug_assert!(cparams.hashLog >= row_log);
cparams.hashLog = cparams.hashLog.min(max_hash_log);
}
cparams
}
#[inline]
fn get_cparam_row_size(src_size_hint: u64, dict_size: usize, mode: c_int) -> u64 {
let mut dict_size = dict_size as u64;
match mode {
ZSTD_RUST_CPM_UNKNOWN | ZSTD_RUST_CPM_NO_ATTACH_DICT | ZSTD_RUST_CPM_CREATE_CDICT => {}
ZSTD_RUST_CPM_ATTACH_DICT => dict_size = 0,
_ => debug_assert!(false, "invalid ZSTD_CParamMode_e"),
}
let unknown = src_size_hint == ZSTD_CONTENTSIZE_UNKNOWN;
let added_size = if unknown && dict_size > 0 { 500 } else { 0 };
if unknown && dict_size == 0 {
ZSTD_CONTENTSIZE_UNKNOWN
} else {
src_size_hint
.wrapping_add(dict_size)
.wrapping_add(added_size)
}
}
/// Selects a raw compression-level-table entry, without strategy cascading or
/// source/dictionary adjustment.
///
/// A C wrapper must apply its active excluded-compressor cascade to the
/// returned strategy before calling [`ZSTD_rust_params_adjustCParams`].
fn select_cparams(
compression_level: c_int,
src_size_hint: u64,
dict_size: usize,
mode: c_int,
) -> ZSTD_compressionParameters {
let row_size = get_cparam_row_size(src_size_hint, dict_size, mode);
let table_id = usize::from(row_size <= 256 * 1024)
+ usize::from(row_size <= 128 * 1024)
+ usize::from(row_size <= 16 * 1024);
let row = if compression_level == 0 {
ZSTD_CLEVEL_DEFAULT
} else if compression_level < 0 {
0
} else {
compression_level.min(ZSTD_MAX_CLEVEL)
} as usize;
let mut cparams = cparams_from_row(DEFAULT_CPARAMS[table_id][row]);
if compression_level < 0 {
let clamped = compression_level.max(ZSTD_rust_params_minCLevel());
cparams.targetLength = (-clamped) as u32;
}
cparams
}
#[inline]
fn make_params(cparams: ZSTD_compressionParameters) -> ZSTD_parameters {
ZSTD_parameters {
cParams: cparams,
fParams: ZSTD_frameParameters {
contentSizeFlag: 1,
checksumFlag: 0,
noDictIDFlag: 0,
},
}
}
#[inline]
fn check_cparams(cparams: ZSTD_compressionParameters) -> usize {
if !within_bounds(ZSTD_C_WINDOW_LOG, cparams.windowLog as c_int)
|| !within_bounds(ZSTD_C_CHAIN_LOG, cparams.chainLog as c_int)
|| !within_bounds(ZSTD_C_HASH_LOG, cparams.hashLog as c_int)
|| !within_bounds(ZSTD_C_SEARCH_LOG, cparams.searchLog as c_int)
|| !within_bounds(ZSTD_C_MIN_MATCH, cparams.minMatch as c_int)
|| !within_bounds(ZSTD_C_TARGET_LENGTH, cparams.targetLength as c_int)
|| !within_bounds(ZSTD_C_STRATEGY, cparams.strategy)
{
ERROR(ZstdErrorCode::ParameterOutOfBound)
} else {
0
}
}
/// Returns the highest table-backed compression level (`ZSTD_MAX_CLEVEL`).
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_maxCLevel() -> c_int {
ZSTD_MAX_CLEVEL
}
/// Returns the lowest public fast level (`-ZSTD_TARGETLENGTH_MAX`).
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_minCLevel() -> c_int {
-ZSTD_TARGETLENGTH_MAX
}
/// Returns the default compression level from `zstd.h`.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_defaultCLevel() -> c_int {
ZSTD_CLEVEL_DEFAULT
}
/// Returns bounds for the seven core compression parameters and compression
/// level. Other `ZSTD_cParameter` cases remain C-owned.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_getBounds(param: c_int) -> ZSTD_bounds {
bounds(param)
}
/// Checks the seven fields of `ZSTD_compressionParameters`.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_checkCParams(cparams: ZSTD_compressionParameters) -> usize {
check_cparams(cparams)
}
/// Clamps the seven fields of `ZSTD_compressionParameters` to public bounds.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_clampCParams(
cparams: ZSTD_compressionParameters,
) -> ZSTD_compressionParameters {
clamp_cparams(cparams)
}
/// C ABI for `ZSTD_cycleLog()`.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_cycleLog(hashLog: u32, strategy: c_int) -> u32 {
cycle_log(hashLog, strategy)
}
/// C ABI for private `ZSTD_getCParamRowSize()`.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_getCParamRowSize(
srcSizeHint: u64,
dictSize: usize,
mode: c_int,
) -> u64 {
get_cparam_row_size(srcSizeHint, dictSize, mode)
}
/// Returns the unadjusted compression-level-table entry.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_selectCParams(
compressionLevel: c_int,
srcSizeHint: u64,
dictSize: usize,
mode: c_int,
) -> ZSTD_compressionParameters {
select_cparams(compressionLevel, srcSizeHint, dictSize, mode)
}
/// Adjusts a validated, strategy-resolved C parameter set.
///
/// See [`adjust_cparams`] for the required C-side policy step.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_adjustCParams(
cparams: ZSTD_compressionParameters,
srcSize: u64,
dictSize: usize,
mode: c_int,
useRowMatchFinder: c_int,
) -> ZSTD_compressionParameters {
adjust_cparams(cparams, srcSize, dictSize, mode, useRowMatchFinder)
}
/// Builds `ZSTD_parameters` with the public default frame parameters.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_makeParams(
cparams: ZSTD_compressionParameters,
) -> ZSTD_parameters {
make_params(cparams)
}
/// Runtime sizes needed to reproduce `ZSTD_sizeof_matchState()` without
/// exposing private C structures to Rust.
///
/// `asanRedzoneSize` is `ZSTD_CWKSP_ASAN_REDZONE_SIZE` when workspace
/// poisoning is enabled and zero otherwise. `matchTSize` and `optimalTSize`
/// must be `sizeof(ZSTD_match_t)` and `sizeof(ZSTD_optimal_t)` respectively.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default)]
pub struct ZSTD_rustMatchStateSizing {
pub hashLog3Max: u32,
pub matchTSize: usize,
pub optimalTSize: usize,
pub asanRedzoneSize: usize,
}
/// C-only layout inputs for `ZSTD_estimateCDictSize_advanced()`.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default)]
pub struct ZSTD_rustCDictSizing {
pub cdictSize: usize,
pub hufWorkspaceSize: usize,
pub hashLog3Max: u32,
pub matchTSize: usize,
pub optimalTSize: usize,
pub asanRedzoneSize: usize,
}
#[inline]
fn 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 cwksp_align(size: usize, alignment: usize) -> usize {
debug_assert!(alignment.is_power_of_two());
size.wrapping_add(alignment - 1) & !(alignment - 1)
}
#[inline]
fn cwksp_aligned64_alloc_size(size: usize, asan_redzone_size: usize) -> usize {
cwksp_alloc_size(cwksp_align(size, 64), asan_redzone_size)
}
#[inline]
fn shift_size(log: u32) -> usize {
debug_assert!(log < usize::BITS);
1usize << log
}
#[inline]
fn allocate_chain_table(strategy: c_int, use_row_match_finder: c_int, for_dds_dict: bool) -> bool {
for_dds_dict
|| (strategy != ZSTD_FAST && !row_match_finder_used(strategy, use_row_match_finder))
}
fn estimate_match_state_size(
cparams: ZSTD_compressionParameters,
use_row_match_finder: c_int,
enable_dedicated_dict_search: bool,
for_cctx: bool,
sizing: ZSTD_rustMatchStateSizing,
) -> usize {
if check_cparams(cparams) != 0 || use_row_match_finder == ZSTD_RUST_PS_AUTO {
return 0;
}
let chain_size = if allocate_chain_table(
cparams.strategy,
use_row_match_finder,
enable_dedicated_dict_search && !for_cctx,
) {
shift_size(cparams.chainLog)
} else {
0
};
let hash_size = shift_size(cparams.hashLog);
let hash_log_3 = if for_cctx && cparams.minMatch == 3 {
cparams.windowLog.min(sizing.hashLog3Max)
} else {
0
};
let hash3_size = if hash_log_3 == 0 {
0
} else {
shift_size(hash_log_3)
};
let table_space = chain_size
.wrapping_mul(size_of::<u32>())
.wrapping_add(hash_size.wrapping_mul(size_of::<u32>()))
.wrapping_add(hash3_size.wrapping_mul(size_of::<u32>()));
let redzone = sizing.asanRedzoneSize;
let opt_potential_space = cwksp_aligned64_alloc_size((52 + 1) * size_of::<u32>(), redzone)
.wrapping_add(cwksp_aligned64_alloc_size(
(35 + 1) * size_of::<u32>(),
redzone,
))
.wrapping_add(cwksp_aligned64_alloc_size(
(31 + 1) * size_of::<u32>(),
redzone,
))
.wrapping_add(cwksp_aligned64_alloc_size(
(1 << 8) * size_of::<u32>(),
redzone,
))
.wrapping_add(cwksp_aligned64_alloc_size(
4099usize.wrapping_mul(sizing.matchTSize),
redzone,
))
.wrapping_add(cwksp_aligned64_alloc_size(
4099usize.wrapping_mul(sizing.optimalTSize),
redzone,
));
let lazy_additional_space = if row_match_finder_used(cparams.strategy, use_row_match_finder) {
cwksp_aligned64_alloc_size(hash_size, redzone)
} else {
0
};
let opt_space = if for_cctx && cparams.strategy >= ZSTD_BTOPT {
opt_potential_space
} else {
0
};
let slack_space = 2 * 64;
table_space
.wrapping_add(opt_space)
.wrapping_add(slack_space)
.wrapping_add(lazy_additional_space)
}
/// Pure leaf for private `ZSTD_sizeof_matchState()`.
///
/// `useRowMatchFinder` must already be resolved to enable or disable. A NULL
/// `sizing` pointer or invalid C parameters returns zero; C never supplies
/// either in a valid estimator call.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_params_estimateMatchStateSize(
cparams: ZSTD_compressionParameters,
useRowMatchFinder: c_int,
enableDedicatedDictSearch: c_int,
forCCtx: u32,
sizing: *const ZSTD_rustMatchStateSizing,
) -> usize {
if sizing.is_null() {
return 0;
}
let sizing = unsafe { *sizing };
estimate_match_state_size(
cparams,
useRowMatchFinder,
enableDedicatedDictSearch != 0,
forCCtx != 0,
sizing,
)
}
#[inline]
fn max_nb_seq(block_size: usize, min_match: u32, use_sequence_producer: bool) -> usize {
let divider = if min_match == 3 || use_sequence_producer {
3
} else {
4
};
block_size / divider
}
/// Pure leaf for private `ZSTD_maxNbSeq()`.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_maxNbSeq(
blockSize: usize,
minMatch: u32,
useSequenceProducer: c_int,
) -> usize {
max_nb_seq(blockSize, minMatch, useSequenceProducer != 0)
}
/// Pure leaf for private `ZSTD_resolveMaxBlockSize()`.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_resolveMaxBlockSize(maxBlockSize: usize) -> usize {
if maxBlockSize == 0 {
ZSTD_BLOCKSIZE_MAX
} else {
maxBlockSize
}
}
fn estimate_cdict_size_from_cparams(
dict_size: usize,
cparams: ZSTD_compressionParameters,
dict_load_method: c_int,
sizing: ZSTD_rustCDictSizing,
) -> usize {
if check_cparams(cparams) != 0 {
return 0;
}
let match_state_sizing = ZSTD_rustMatchStateSizing {
hashLog3Max: sizing.hashLog3Max,
matchTSize: sizing.matchTSize,
optimalTSize: sizing.optimalTSize,
asanRedzoneSize: sizing.asanRedzoneSize,
};
let row_match_finder = resolve_row_match_finder(ZSTD_RUST_PS_AUTO, cparams);
let copied_dict_space = if dict_load_method == 1 {
0
} else {
cwksp_alloc_size(
cwksp_align(dict_size, size_of::<usize>()),
sizing.asanRedzoneSize,
)
};
cwksp_alloc_size(sizing.cdictSize, sizing.asanRedzoneSize)
.wrapping_add(cwksp_alloc_size(
sizing.hufWorkspaceSize,
sizing.asanRedzoneSize,
))
.wrapping_add(estimate_match_state_size(
cparams,
row_match_finder,
true,
false,
match_state_sizing,
))
.wrapping_add(copied_dict_space)
}
/// Parameter-only leaf for `ZSTD_estimateCDictSize_advanced()`.
///
/// C retains ownership of `sizeof(ZSTD_CDict)`, HUF workspace configuration,
/// and sanitizer workspace policy, then passes them in `sizing`. A NULL sizing
/// pointer returns zero.
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_params_estimateCDictSizeFromCParams(
dictSize: usize,
cparams: ZSTD_compressionParameters,
dictLoadMethod: c_int,
sizing: *const ZSTD_rustCDictSizing,
) -> usize {
if sizing.is_null() {
return 0;
}
estimate_cdict_size_from_cparams(dictSize, cparams, dictLoadMethod, unsafe { *sizing })
}
#[cfg(test)]
mod tests {
use super::*;
use crate::errors::ERR_isError;
use std::mem::{align_of, size_of};
fn adjust_public(
cparams: ZSTD_compressionParameters,
src_size: u64,
dict_size: usize,
) -> ZSTD_compressionParameters {
let src_size = if src_size == 0 {
ZSTD_CONTENTSIZE_UNKNOWN
} else {
src_size
};
adjust_cparams(
clamp_cparams(cparams),
src_size,
dict_size,
ZSTD_RUST_CPM_UNKNOWN,
ZSTD_RUST_PS_AUTO,
)
}
#[test]
fn abi_parameter_layouts_match_zstd_h() {
assert_eq!(
size_of::<ZSTD_compressionParameters>(),
7 * size_of::<u32>()
);
assert_eq!(align_of::<ZSTD_compressionParameters>(), align_of::<u32>());
assert_eq!(size_of::<ZSTD_frameParameters>(), 3 * size_of::<c_int>());
assert_eq!(size_of::<ZSTD_parameters>(), 10 * size_of::<u32>());
assert_eq!(
size_of::<ZSTD_bounds>(),
size_of::<usize>() + 2 * size_of::<c_int>()
);
}
#[test]
fn level_tables_match_representative_clevels_entries() {
let large = select_cparams(3, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_RUST_CPM_UNKNOWN);
assert_eq!(
large,
ZSTD_compressionParameters {
windowLog: 21,
chainLog: 16,
hashLog: 17,
searchLog: 1,
minMatch: 5,
targetLength: 0,
strategy: ZSTD_DFAST,
}
);
let small = select_cparams(3, 16 * 1024, 0, ZSTD_RUST_CPM_UNKNOWN);
assert_eq!(
small,
ZSTD_compressionParameters {
windowLog: 14,
chainLog: 14,
hashLog: 15,
searchLog: 2,
minMatch: 4,
targetLength: 0,
strategy: ZSTD_DFAST,
}
);
let fast = select_cparams(-5, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_RUST_CPM_UNKNOWN);
assert_eq!(fast.strategy, ZSTD_FAST);
assert_eq!(fast.targetLength, 5);
assert_eq!(
select_cparams(999, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_RUST_CPM_UNKNOWN),
select_cparams(22, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_RUST_CPM_UNKNOWN)
);
}
#[test]
fn adjustment_clamps_and_downsizes_like_the_c_leaf() {
let input = ZSTD_compressionParameters {
windowLog: 31,
chainLog: 30,
hashLog: 30,
searchLog: 1,
minMatch: 3,
targetLength: 0,
strategy: ZSTD_BTOPT,
};
let adjusted = adjust_public(input, 1, 0);
assert_eq!(adjusted.windowLog, 10);
/* C applies WINDOWLOG_ABSOLUTEMIN only after it has used the smaller
* temporary window to downsize the hash and chain logs. */
assert_eq!(adjusted.hashLog, 7);
assert_eq!(adjusted.chainLog, 7);
assert_eq!(ZSTD_rust_params_checkCParams(adjusted), 0);
let clamped = ZSTD_rust_params_clampCParams(ZSTD_compressionParameters {
windowLog: u32::MAX,
chainLog: 0,
hashLog: 0,
searchLog: 0,
minMatch: 0,
targetLength: u32::MAX,
strategy: 99,
});
assert_eq!(clamped.windowLog, ZSTD_WINDOWLOG_MIN as u32);
assert_eq!(clamped.chainLog, ZSTD_CHAINLOG_MIN as u32);
assert_eq!(clamped.hashLog, ZSTD_HASHLOG_MIN as u32);
assert_eq!(clamped.searchLog, ZSTD_SEARCHLOG_MIN as u32);
assert_eq!(clamped.minMatch, ZSTD_MINMATCH_MIN as u32);
assert_eq!(clamped.targetLength, ZSTD_TARGETLENGTH_MIN as u32);
assert_eq!(clamped.strategy, ZSTD_BTULTRA2);
}
#[test]
fn checking_and_bounds_preserve_the_public_error_contract() {
let valid = select_cparams(1, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_RUST_CPM_UNKNOWN);
assert_eq!(check_cparams(valid), 0);
let mut invalid = valid;
invalid.minMatch = 2;
assert!(ERR_isError(check_cparams(invalid)));
let bounds = ZSTD_rust_params_getBounds(ZSTD_C_HASH_LOG);
assert_eq!(bounds.error, 0);
assert_eq!(bounds.lowerBound, 6);
assert_eq!(bounds.upperBound, 30);
assert!(ERR_isError(ZSTD_rust_params_getBounds(-1).error));
}
#[test]
fn params_default_frame_flags_match_c() {
let cparams = select_cparams(5, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_RUST_CPM_UNKNOWN);
let params = ZSTD_rust_params_makeParams(cparams);
assert_eq!(params.cParams, cparams);
assert_eq!(params.fParams.contentSizeFlag, 1);
assert_eq!(params.fParams.checksumFlag, 0);
assert_eq!(params.fParams.noDictIDFlag, 0);
}
#[test]
fn row_size_preserves_unknown_dictionary_overflow_semantics() {
assert_eq!(
get_cparam_row_size(ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_RUST_CPM_UNKNOWN),
ZSTD_CONTENTSIZE_UNKNOWN
);
assert_eq!(
get_cparam_row_size(ZSTD_CONTENTSIZE_UNKNOWN, 1, ZSTD_RUST_CPM_UNKNOWN),
500
);
assert_eq!(
get_cparam_row_size(128 * 1024, 1, ZSTD_RUST_CPM_ATTACH_DICT),
128 * 1024
);
}
#[test]
fn match_state_sizing_reproduces_table_and_row_rules() {
let sizing = ZSTD_rustMatchStateSizing {
hashLog3Max: 17,
matchTSize: 16,
optimalTSize: 32,
asanRedzoneSize: 0,
};
let fast = ZSTD_compressionParameters {
windowLog: 10,
chainLog: 10,
hashLog: 10,
searchLog: 1,
minMatch: 4,
targetLength: 0,
strategy: ZSTD_FAST,
};
assert_eq!(
estimate_match_state_size(fast, ZSTD_RUST_PS_DISABLE, false, true, sizing),
4096 + 128
);
let row = ZSTD_compressionParameters {
windowLog: 15,
chainLog: 10,
hashLog: 10,
searchLog: 4,
minMatch: 4,
targetLength: 0,
strategy: ZSTD_GREEDY,
};
assert_eq!(
estimate_match_state_size(row, ZSTD_RUST_PS_ENABLE, false, true, sizing),
4096 + 1024 + 128
);
assert_eq!(ZSTD_rust_params_maxNbSeq(100, 3, 0), 33);
assert_eq!(ZSTD_rust_params_maxNbSeq(100, 4, 0), 25);
assert_eq!(ZSTD_rust_params_resolveMaxBlockSize(0), 128 * 1024);
}
}