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feat(rust): port superblock compression

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Move subblock partitioning, literal and sequence section emission, entropy
fallback, and repcode repair into Rust. Keep a narrow C wrapper to read the
opaque compression context and invoke the existing C entropy-stat builder;
the Rust side owns only verified C-shaped leaf layouts.

Test Plan:
- cargo clippy
- cargo clippy --benches
- cargo clippy --tests
- cargo +nightly fmt
- cargo test zstd_compress_superblock::tests -- --nocapture
- cargo test --target i686-unknown-linux-gnu zstd_compress_superblock::tests
- byte-exact C control across 16 target-size and input-shape cases
- fuzzer, zstreamtest, invalidDictionaries, and bounded native test matrix

Refs: Rust sequence entropy port 887af204
This commit is contained in:
ddidderr
2026-07-10 22:45:22 +02:00
parent 887af204df
commit fde1d70cc5
3 changed files with 1244 additions and 663 deletions
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lib/compress/zstd_compress_superblock.c
+30 -663
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@@ -8,681 +8,48 @@
* You may select, at your option, one of the above-listed licenses.
*/
/*-*************************************
* Dependencies
***************************************/
/* The implementation lives in rust/src/zstd_compress_superblock.rs. Keep the
* context extraction here: ZSTD_CCtx is intentionally opaque to Rust, while
* the small sequence and entropy leaf layouts are asserted in both sources. */
#include "zstd_compress_superblock.h"
#include "zstd_compress_internal.h"
#include "../common/zstd_internal.h" /* ZSTD_getSequenceLength */
#include "hist.h" /* HIST_countFast_wksp */
#include "zstd_compress_internal.h" /* ZSTD_[huf|fse|entropy]CTablesMetadata_t */
#include "zstd_compress_sequences.h"
#include "zstd_compress_literals.h"
typedef char ZSTD_rust_superblock_seqdef_layout[(sizeof(SeqDef) == 8) ? 1 : -1];
typedef char ZSTD_rust_superblock_fse_layout[(sizeof(ZSTD_fseCTables_t) == 3552) ? 1 : -1];
typedef char ZSTD_rust_superblock_entropy_offset[
(offsetof(ZSTD_compressedBlockState_t, entropy) == 0) ? 1 : -1];
typedef char ZSTD_rust_superblock_rep_offset[
(offsetof(ZSTD_compressedBlockState_t, rep) == sizeof(ZSTD_entropyCTables_t)) ? 1 : -1];
typedef char ZSTD_rust_superblock_seqstore_long_length_pos[
(offsetof(SeqStore_t, longLengthPos) == 9 * sizeof(size_t) + 4) ? 1 : -1];
typedef char ZSTD_rust_superblock_seqstore_layout[
(sizeof(SeqStore_t) == 9 * sizeof(size_t) + 8) ? 1 : -1];
/** ZSTD_compressSubBlock_literal() :
* Compresses literals section for a sub-block.
* When we have to write the Huffman table we will sometimes choose a header
* size larger than necessary. This is because we have to pick the header size
* before we know the table size + compressed size, so we have a bound on the
* table size. If we guessed incorrectly, we fall back to uncompressed literals.
*
* We write the header when writeEntropy=1 and set entropyWritten=1 when we succeeded
* in writing the header, otherwise it is set to 0.
*
* hufMetadata->hType has literals block type info.
* If it is set_basic, all sub-blocks literals section will be Raw_Literals_Block.
* If it is set_rle, all sub-blocks literals section will be RLE_Literals_Block.
* If it is set_compressed, first sub-block's literals section will be Compressed_Literals_Block
* If it is set_compressed, first sub-block's literals section will be Treeless_Literals_Block
* and the following sub-blocks' literals sections will be Treeless_Literals_Block.
* @return : compressed size of literals section of a sub-block
* Or 0 if unable to compress.
* Or error code */
static size_t
ZSTD_compressSubBlock_literal(const HUF_CElt* hufTable,
const ZSTD_hufCTablesMetadata_t* hufMetadata,
const BYTE* literals, size_t litSize,
void* dst, size_t dstSize,
const int bmi2, int writeEntropy, int* entropyWritten)
{
size_t const header = writeEntropy ? 200 : 0;
size_t const lhSize = 3 + (litSize >= (1 KB - header)) + (litSize >= (16 KB - header));
BYTE* const ostart = (BYTE*)dst;
BYTE* const oend = ostart + dstSize;
BYTE* op = ostart + lhSize;
U32 const singleStream = lhSize == 3;
SymbolEncodingType_e hType = writeEntropy ? hufMetadata->hType : set_repeat;
size_t cLitSize = 0;
DEBUGLOG(5, "ZSTD_compressSubBlock_literal (litSize=%zu, lhSize=%zu, writeEntropy=%d)", litSize, lhSize, writeEntropy);
*entropyWritten = 0;
if (litSize == 0 || hufMetadata->hType == set_basic) {
DEBUGLOG(5, "ZSTD_compressSubBlock_literal using raw literal");
return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize);
} else if (hufMetadata->hType == set_rle) {
DEBUGLOG(5, "ZSTD_compressSubBlock_literal using rle literal");
return ZSTD_compressRleLiteralsBlock(dst, dstSize, literals, litSize);
}
assert(litSize > 0);
assert(hufMetadata->hType == set_compressed || hufMetadata->hType == set_repeat);
if (writeEntropy && hufMetadata->hType == set_compressed) {
ZSTD_memcpy(op, hufMetadata->hufDesBuffer, hufMetadata->hufDesSize);
op += hufMetadata->hufDesSize;
cLitSize += hufMetadata->hufDesSize;
DEBUGLOG(5, "ZSTD_compressSubBlock_literal (hSize=%zu)", hufMetadata->hufDesSize);
}
{ int const flags = bmi2 ? HUF_flags_bmi2 : 0;
const size_t cSize = singleStream ? HUF_compress1X_usingCTable(op, (size_t)(oend-op), literals, litSize, hufTable, flags)
: HUF_compress4X_usingCTable(op, (size_t)(oend-op), literals, litSize, hufTable, flags);
op += cSize;
cLitSize += cSize;
if (cSize == 0 || ERR_isError(cSize)) {
DEBUGLOG(5, "Failed to write entropy tables %s", ZSTD_getErrorName(cSize));
return 0;
}
/* If we expand and we aren't writing a header then emit uncompressed */
if (!writeEntropy && cLitSize >= litSize) {
DEBUGLOG(5, "ZSTD_compressSubBlock_literal using raw literal because uncompressible");
return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize);
}
/* If we are writing headers then allow expansion that doesn't change our header size. */
if (lhSize < (size_t)(3 + (cLitSize >= 1 KB) + (cLitSize >= 16 KB))) {
assert(cLitSize > litSize);
DEBUGLOG(5, "Literals expanded beyond allowed header size");
return ZSTD_noCompressLiterals(dst, dstSize, literals, litSize);
}
DEBUGLOG(5, "ZSTD_compressSubBlock_literal (cSize=%zu)", cSize);
}
/* Build header */
switch(lhSize)
{
case 3: /* 2 - 2 - 10 - 10 */
{ U32 const lhc = hType + ((U32)(!singleStream) << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<14);
MEM_writeLE24(ostart, lhc);
break;
}
case 4: /* 2 - 2 - 14 - 14 */
{ U32 const lhc = hType + (2 << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<18);
MEM_writeLE32(ostart, lhc);
break;
}
case 5: /* 2 - 2 - 18 - 18 */
{ U32 const lhc = hType + (3 << 2) + ((U32)litSize<<4) + ((U32)cLitSize<<22);
MEM_writeLE32(ostart, lhc);
ostart[4] = (BYTE)(cLitSize >> 10);
break;
}
default: /* not possible : lhSize is {3,4,5} */
assert(0);
}
*entropyWritten = 1;
DEBUGLOG(5, "Compressed literals: %u -> %u", (U32)litSize, (U32)(op-ostart));
return (size_t)(op-ostart);
}
static size_t
ZSTD_seqDecompressedSize(SeqStore_t const* seqStore,
const SeqDef* sequences, size_t nbSeqs,
size_t litSize, int lastSubBlock)
{
size_t matchLengthSum = 0;
size_t litLengthSum = 0;
size_t n;
for (n=0; n<nbSeqs; n++) {
const ZSTD_SequenceLength seqLen = ZSTD_getSequenceLength(seqStore, sequences+n);
litLengthSum += seqLen.litLength;
matchLengthSum += seqLen.matchLength;
}
DEBUGLOG(5, "ZSTD_seqDecompressedSize: %u sequences from %p: %u literals + %u matchlength",
(unsigned)nbSeqs, (const void*)sequences,
(unsigned)litLengthSum, (unsigned)matchLengthSum);
if (!lastSubBlock)
assert(litLengthSum == litSize);
else
assert(litLengthSum <= litSize);
(void)litLengthSum;
return matchLengthSum + litSize;
}
/** ZSTD_compressSubBlock_sequences() :
* Compresses sequences section for a sub-block.
* fseMetadata->llType, fseMetadata->ofType, and fseMetadata->mlType have
* symbol compression modes for the super-block.
* The first successfully compressed block will have these in its header.
* We set entropyWritten=1 when we succeed in compressing the sequences.
* The following sub-blocks will always have repeat mode.
* @return : compressed size of sequences section of a sub-block
* Or 0 if it is unable to compress
* Or error code. */
static size_t
ZSTD_compressSubBlock_sequences(const ZSTD_fseCTables_t* fseTables,
const ZSTD_fseCTablesMetadata_t* fseMetadata,
const SeqDef* sequences, size_t nbSeq,
const BYTE* llCode, const BYTE* mlCode, const BYTE* ofCode,
const ZSTD_CCtx_params* cctxParams,
void* dst, size_t dstCapacity,
const int bmi2, int writeEntropy, int* entropyWritten)
{
const int longOffsets = cctxParams->cParams.windowLog > STREAM_ACCUMULATOR_MIN;
BYTE* const ostart = (BYTE*)dst;
BYTE* const oend = ostart + dstCapacity;
BYTE* op = ostart;
BYTE* seqHead;
DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (nbSeq=%zu, writeEntropy=%d, longOffsets=%d)", nbSeq, writeEntropy, longOffsets);
*entropyWritten = 0;
/* Sequences Header */
RETURN_ERROR_IF((oend-op) < 3 /*max nbSeq Size*/ + 1 /*seqHead*/,
dstSize_tooSmall, "");
if (nbSeq < 128)
*op++ = (BYTE)nbSeq;
else if (nbSeq < LONGNBSEQ)
op[0] = (BYTE)((nbSeq>>8) + 0x80), op[1] = (BYTE)nbSeq, op+=2;
else
op[0]=0xFF, MEM_writeLE16(op+1, (U16)(nbSeq - LONGNBSEQ)), op+=3;
if (nbSeq==0) {
return (size_t)(op - ostart);
}
/* seqHead : flags for FSE encoding type */
seqHead = op++;
DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (seqHeadSize=%u)", (unsigned)(op-ostart));
if (writeEntropy) {
const U32 LLtype = fseMetadata->llType;
const U32 Offtype = fseMetadata->ofType;
const U32 MLtype = fseMetadata->mlType;
DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (fseTablesSize=%zu)", fseMetadata->fseTablesSize);
*seqHead = (BYTE)((LLtype<<6) + (Offtype<<4) + (MLtype<<2));
ZSTD_memcpy(op, fseMetadata->fseTablesBuffer, fseMetadata->fseTablesSize);
op += fseMetadata->fseTablesSize;
} else {
const U32 repeat = set_repeat;
*seqHead = (BYTE)((repeat<<6) + (repeat<<4) + (repeat<<2));
}
{ size_t const bitstreamSize = ZSTD_encodeSequences(
op, (size_t)(oend - op),
fseTables->matchlengthCTable, mlCode,
fseTables->offcodeCTable, ofCode,
fseTables->litlengthCTable, llCode,
sequences, nbSeq,
longOffsets, bmi2);
FORWARD_IF_ERROR(bitstreamSize, "ZSTD_encodeSequences failed");
op += bitstreamSize;
/* zstd versions <= 1.3.4 mistakenly report corruption when
* FSE_readNCount() receives a buffer < 4 bytes.
* Fixed by https://github.com/facebook/zstd/pull/1146.
* This can happen when the last set_compressed table present is 2
* bytes and the bitstream is only one byte.
* In this exceedingly rare case, we will simply emit an uncompressed
* block, since it isn't worth optimizing.
*/
#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if (writeEntropy && fseMetadata->lastCountSize && fseMetadata->lastCountSize + bitstreamSize < 4) {
/* NCountSize >= 2 && bitstreamSize > 0 ==> lastCountSize == 3 */
assert(fseMetadata->lastCountSize + bitstreamSize == 3);
DEBUGLOG(5, "Avoiding bug in zstd decoder in versions <= 1.3.4 by "
"emitting an uncompressed block.");
return 0;
}
#endif
DEBUGLOG(5, "ZSTD_compressSubBlock_sequences (bitstreamSize=%zu)", bitstreamSize);
}
/* zstd versions <= 1.4.0 mistakenly report error when
* sequences section body size is less than 3 bytes.
* Fixed by https://github.com/facebook/zstd/pull/1664.
* This can happen when the previous sequences section block is compressed
* with rle mode and the current block's sequences section is compressed
* with repeat mode where sequences section body size can be 1 byte.
*/
#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if (op-seqHead < 4) {
DEBUGLOG(5, "Avoiding bug in zstd decoder in versions <= 1.4.0 by emitting "
"an uncompressed block when sequences are < 4 bytes");
return 0;
}
#endif
*entropyWritten = 1;
return (size_t)(op - ostart);
}
/** ZSTD_compressSubBlock() :
* Compresses a single sub-block.
* @return : compressed size of the sub-block
* Or 0 if it failed to compress. */
static size_t ZSTD_compressSubBlock(const ZSTD_entropyCTables_t* entropy,
const ZSTD_entropyCTablesMetadata_t* entropyMetadata,
const SeqDef* sequences, size_t nbSeq,
const BYTE* literals, size_t litSize,
const BYTE* llCode, const BYTE* mlCode, const BYTE* ofCode,
const ZSTD_CCtx_params* cctxParams,
void* dst, size_t dstCapacity,
const int bmi2,
int writeLitEntropy, int writeSeqEntropy,
int* litEntropyWritten, int* seqEntropyWritten,
U32 lastBlock)
{
BYTE* const ostart = (BYTE*)dst;
BYTE* const oend = ostart + dstCapacity;
BYTE* op = ostart + ZSTD_blockHeaderSize;
DEBUGLOG(5, "ZSTD_compressSubBlock (litSize=%zu, nbSeq=%zu, writeLitEntropy=%d, writeSeqEntropy=%d, lastBlock=%d)",
litSize, nbSeq, writeLitEntropy, writeSeqEntropy, lastBlock);
{ size_t cLitSize = ZSTD_compressSubBlock_literal((const HUF_CElt*)entropy->huf.CTable,
&entropyMetadata->hufMetadata, literals, litSize,
op, (size_t)(oend-op),
bmi2, writeLitEntropy, litEntropyWritten);
FORWARD_IF_ERROR(cLitSize, "ZSTD_compressSubBlock_literal failed");
if (cLitSize == 0) return 0;
op += cLitSize;
}
{ size_t cSeqSize = ZSTD_compressSubBlock_sequences(&entropy->fse,
&entropyMetadata->fseMetadata,
sequences, nbSeq,
llCode, mlCode, ofCode,
cctxParams,
op, (size_t)(oend-op),
bmi2, writeSeqEntropy, seqEntropyWritten);
FORWARD_IF_ERROR(cSeqSize, "ZSTD_compressSubBlock_sequences failed");
if (cSeqSize == 0) return 0;
op += cSeqSize;
}
/* Write block header */
{ size_t cSize = (size_t)(op-ostart) - ZSTD_blockHeaderSize;
U32 const cBlockHeader24 = lastBlock + (((U32)bt_compressed)<<1) + (U32)(cSize << 3);
MEM_writeLE24(ostart, cBlockHeader24);
}
return (size_t)(op-ostart);
}
static size_t ZSTD_estimateSubBlockSize_literal(const BYTE* literals, size_t litSize,
const ZSTD_hufCTables_t* huf,
const ZSTD_hufCTablesMetadata_t* hufMetadata,
void* workspace, size_t wkspSize,
int writeEntropy)
{
unsigned* const countWksp = (unsigned*)workspace;
unsigned maxSymbolValue = 255;
size_t literalSectionHeaderSize = 3; /* Use hard coded size of 3 bytes */
if (hufMetadata->hType == set_basic) return litSize;
else if (hufMetadata->hType == set_rle) return 1;
else if (hufMetadata->hType == set_compressed || hufMetadata->hType == set_repeat) {
size_t const largest = HIST_count_wksp (countWksp, &maxSymbolValue, (const BYTE*)literals, litSize, workspace, wkspSize);
if (ZSTD_isError(largest)) return litSize;
{ size_t cLitSizeEstimate = HUF_estimateCompressedSize((const HUF_CElt*)huf->CTable, countWksp, maxSymbolValue);
if (writeEntropy) cLitSizeEstimate += hufMetadata->hufDesSize;
return cLitSizeEstimate + literalSectionHeaderSize;
} }
assert(0); /* impossible */
return 0;
}
static size_t ZSTD_estimateSubBlockSize_symbolType(SymbolEncodingType_e type,
const BYTE* codeTable, unsigned maxCode,
size_t nbSeq, const FSE_CTable* fseCTable,
const U8* additionalBits,
short const* defaultNorm, U32 defaultNormLog, U32 defaultMax,
void* workspace, size_t wkspSize)
{
unsigned* const countWksp = (unsigned*)workspace;
const BYTE* ctp = codeTable;
const BYTE* const ctStart = ctp;
const BYTE* const ctEnd = ctStart + nbSeq;
size_t cSymbolTypeSizeEstimateInBits = 0;
unsigned max = maxCode;
HIST_countFast_wksp(countWksp, &max, codeTable, nbSeq, workspace, wkspSize); /* can't fail */
if (type == set_basic) {
/* We selected this encoding type, so it must be valid. */
assert(max <= defaultMax);
cSymbolTypeSizeEstimateInBits = max <= defaultMax
? ZSTD_crossEntropyCost(defaultNorm, defaultNormLog, countWksp, max)
: ERROR(GENERIC);
} else if (type == set_rle) {
cSymbolTypeSizeEstimateInBits = 0;
} else if (type == set_compressed || type == set_repeat) {
cSymbolTypeSizeEstimateInBits = ZSTD_fseBitCost(fseCTable, countWksp, max);
}
if (ZSTD_isError(cSymbolTypeSizeEstimateInBits)) return nbSeq * 10;
while (ctp < ctEnd) {
if (additionalBits) cSymbolTypeSizeEstimateInBits += additionalBits[*ctp];
else cSymbolTypeSizeEstimateInBits += *ctp; /* for offset, offset code is also the number of additional bits */
ctp++;
}
return cSymbolTypeSizeEstimateInBits / 8;
}
static size_t ZSTD_estimateSubBlockSize_sequences(const BYTE* ofCodeTable,
const BYTE* llCodeTable,
const BYTE* mlCodeTable,
size_t nbSeq,
const ZSTD_fseCTables_t* fseTables,
const ZSTD_fseCTablesMetadata_t* fseMetadata,
void* workspace, size_t wkspSize,
int writeEntropy)
{
size_t const sequencesSectionHeaderSize = 3; /* Use hard coded size of 3 bytes */
size_t cSeqSizeEstimate = 0;
if (nbSeq == 0) return sequencesSectionHeaderSize;
cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->ofType, ofCodeTable, MaxOff,
nbSeq, fseTables->offcodeCTable, NULL,
OF_defaultNorm, OF_defaultNormLog, DefaultMaxOff,
workspace, wkspSize);
cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->llType, llCodeTable, MaxLL,
nbSeq, fseTables->litlengthCTable, LL_bits,
LL_defaultNorm, LL_defaultNormLog, MaxLL,
workspace, wkspSize);
cSeqSizeEstimate += ZSTD_estimateSubBlockSize_symbolType(fseMetadata->mlType, mlCodeTable, MaxML,
nbSeq, fseTables->matchlengthCTable, ML_bits,
ML_defaultNorm, ML_defaultNormLog, MaxML,
workspace, wkspSize);
if (writeEntropy) cSeqSizeEstimate += fseMetadata->fseTablesSize;
return cSeqSizeEstimate + sequencesSectionHeaderSize;
}
typedef struct {
size_t estLitSize;
size_t estBlockSize;
} EstimatedBlockSize;
static EstimatedBlockSize ZSTD_estimateSubBlockSize(const BYTE* literals, size_t litSize,
const BYTE* ofCodeTable,
const BYTE* llCodeTable,
const BYTE* mlCodeTable,
size_t nbSeq,
const ZSTD_entropyCTables_t* entropy,
const ZSTD_entropyCTablesMetadata_t* entropyMetadata,
void* workspace, size_t wkspSize,
int writeLitEntropy, int writeSeqEntropy)
{
EstimatedBlockSize ebs;
ebs.estLitSize = ZSTD_estimateSubBlockSize_literal(literals, litSize,
&entropy->huf, &entropyMetadata->hufMetadata,
workspace, wkspSize, writeLitEntropy);
ebs.estBlockSize = ZSTD_estimateSubBlockSize_sequences(ofCodeTable, llCodeTable, mlCodeTable,
nbSeq, &entropy->fse, &entropyMetadata->fseMetadata,
workspace, wkspSize, writeSeqEntropy);
ebs.estBlockSize += ebs.estLitSize + ZSTD_blockHeaderSize;
return ebs;
}
static int ZSTD_needSequenceEntropyTables(ZSTD_fseCTablesMetadata_t const* fseMetadata)
{
if (fseMetadata->llType == set_compressed || fseMetadata->llType == set_rle)
return 1;
if (fseMetadata->mlType == set_compressed || fseMetadata->mlType == set_rle)
return 1;
if (fseMetadata->ofType == set_compressed || fseMetadata->ofType == set_rle)
return 1;
return 0;
}
static size_t countLiterals(SeqStore_t const* seqStore, const SeqDef* sp, size_t seqCount)
{
size_t n, total = 0;
assert(sp != NULL);
for (n=0; n<seqCount; n++) {
total += ZSTD_getSequenceLength(seqStore, sp+n).litLength;
}
DEBUGLOG(6, "countLiterals for %zu sequences from %p => %zu bytes", seqCount, (const void*)sp, total);
return total;
}
#define BYTESCALE 256
static size_t sizeBlockSequences(const SeqDef* sp, size_t nbSeqs,
size_t targetBudget, size_t avgLitCost, size_t avgSeqCost,
int firstSubBlock)
{
size_t n, budget = 0, inSize=0;
/* entropy headers */
size_t const headerSize = (size_t)firstSubBlock * 120 * BYTESCALE; /* generous estimate */
assert(firstSubBlock==0 || firstSubBlock==1);
budget += headerSize;
/* first sequence => at least one sequence*/
budget += sp[0].litLength * avgLitCost + avgSeqCost;
if (budget > targetBudget) return 1;
inSize = sp[0].litLength + (sp[0].mlBase+MINMATCH);
/* loop over sequences */
for (n=1; n<nbSeqs; n++) {
size_t currentCost = sp[n].litLength * avgLitCost + avgSeqCost;
budget += currentCost;
inSize += sp[n].litLength + (sp[n].mlBase+MINMATCH);
/* stop when sub-block budget is reached */
if ( (budget > targetBudget)
/* though continue to expand until the sub-block is deemed compressible */
&& (budget < inSize * BYTESCALE) )
break;
}
return n;
}
/** ZSTD_compressSubBlock_multi() :
* Breaks super-block into multiple sub-blocks and compresses them.
* Entropy will be written into the first block.
* The following blocks use repeat_mode to compress.
* Sub-blocks are all compressed, except the last one when beneficial.
* @return : compressed size of the super block (which features multiple ZSTD blocks)
* or 0 if it failed to compress. */
static size_t ZSTD_compressSubBlock_multi(const SeqStore_t* seqStorePtr,
const ZSTD_compressedBlockState_t* prevCBlock,
ZSTD_compressedBlockState_t* nextCBlock,
const ZSTD_entropyCTablesMetadata_t* entropyMetadata,
const ZSTD_CCtx_params* cctxParams,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
const int bmi2, U32 lastBlock,
void* workspace, size_t wkspSize)
{
const SeqDef* const sstart = seqStorePtr->sequencesStart;
const SeqDef* const send = seqStorePtr->sequences;
const SeqDef* sp = sstart; /* tracks progresses within seqStorePtr->sequences */
size_t const nbSeqs = (size_t)(send - sstart);
const BYTE* const lstart = seqStorePtr->litStart;
const BYTE* const lend = seqStorePtr->lit;
const BYTE* lp = lstart;
size_t const nbLiterals = (size_t)(lend - lstart);
BYTE const* ip = (BYTE const*)src;
BYTE const* const iend = ip + srcSize;
BYTE* const ostart = (BYTE*)dst;
BYTE* const oend = ostart + dstCapacity;
BYTE* op = ostart;
const BYTE* llCodePtr = seqStorePtr->llCode;
const BYTE* mlCodePtr = seqStorePtr->mlCode;
const BYTE* ofCodePtr = seqStorePtr->ofCode;
size_t const minTarget = ZSTD_TARGETCBLOCKSIZE_MIN; /* enforce minimum size, to reduce undesirable side effects */
size_t const targetCBlockSize = MAX(minTarget, cctxParams->targetCBlockSize);
int writeLitEntropy = (entropyMetadata->hufMetadata.hType == set_compressed);
int writeSeqEntropy = 1;
DEBUGLOG(5, "ZSTD_compressSubBlock_multi (srcSize=%u, litSize=%u, nbSeq=%u)",
(unsigned)srcSize, (unsigned)(lend-lstart), (unsigned)(send-sstart));
/* let's start by a general estimation for the full block */
if (nbSeqs > 0) {
EstimatedBlockSize const ebs =
ZSTD_estimateSubBlockSize(lp, nbLiterals,
ofCodePtr, llCodePtr, mlCodePtr, nbSeqs,
&nextCBlock->entropy, entropyMetadata,
workspace, wkspSize,
writeLitEntropy, writeSeqEntropy);
/* quick estimation */
size_t const avgLitCost = nbLiterals ? (ebs.estLitSize * BYTESCALE) / nbLiterals : BYTESCALE;
size_t const avgSeqCost = ((ebs.estBlockSize - ebs.estLitSize) * BYTESCALE) / nbSeqs;
const size_t nbSubBlocks = MAX((ebs.estBlockSize + (targetCBlockSize/2)) / targetCBlockSize, 1);
size_t n, avgBlockBudget, blockBudgetSupp=0;
avgBlockBudget = (ebs.estBlockSize * BYTESCALE) / nbSubBlocks;
DEBUGLOG(5, "estimated fullblock size=%u bytes ; avgLitCost=%.2f ; avgSeqCost=%.2f ; targetCBlockSize=%u, nbSubBlocks=%u ; avgBlockBudget=%.0f bytes",
(unsigned)ebs.estBlockSize, (double)avgLitCost/BYTESCALE, (double)avgSeqCost/BYTESCALE,
(unsigned)targetCBlockSize, (unsigned)nbSubBlocks, (double)avgBlockBudget/BYTESCALE);
/* simplification: if estimates states that the full superblock doesn't compress, just bail out immediately
* this will result in the production of a single uncompressed block covering @srcSize.*/
if (ebs.estBlockSize > srcSize) return 0;
/* compress and write sub-blocks */
assert(nbSubBlocks>0);
for (n=0; n < nbSubBlocks-1; n++) {
/* determine nb of sequences for current sub-block + nbLiterals from next sequence */
size_t const seqCount = sizeBlockSequences(sp, (size_t)(send-sp),
avgBlockBudget + blockBudgetSupp, avgLitCost, avgSeqCost, n==0);
/* if reached last sequence : break to last sub-block (simplification) */
assert(seqCount <= (size_t)(send-sp));
if (sp + seqCount == send) break;
assert(seqCount > 0);
/* compress sub-block */
{ int litEntropyWritten = 0;
int seqEntropyWritten = 0;
size_t litSize = countLiterals(seqStorePtr, sp, seqCount);
const size_t decompressedSize =
ZSTD_seqDecompressedSize(seqStorePtr, sp, seqCount, litSize, 0);
size_t const cSize = ZSTD_compressSubBlock(&nextCBlock->entropy, entropyMetadata,
sp, seqCount,
lp, litSize,
llCodePtr, mlCodePtr, ofCodePtr,
cctxParams,
op, (size_t)(oend-op),
bmi2, writeLitEntropy, writeSeqEntropy,
&litEntropyWritten, &seqEntropyWritten,
0);
FORWARD_IF_ERROR(cSize, "ZSTD_compressSubBlock failed");
/* check compressibility, update state components */
if (cSize > 0 && cSize < decompressedSize) {
DEBUGLOG(5, "Committed sub-block compressing %u bytes => %u bytes",
(unsigned)decompressedSize, (unsigned)cSize);
assert(ip + decompressedSize <= iend);
ip += decompressedSize;
lp += litSize;
op += cSize;
llCodePtr += seqCount;
mlCodePtr += seqCount;
ofCodePtr += seqCount;
/* Entropy only needs to be written once */
if (litEntropyWritten) {
writeLitEntropy = 0;
}
if (seqEntropyWritten) {
writeSeqEntropy = 0;
}
sp += seqCount;
blockBudgetSupp = 0;
} }
/* otherwise : do not compress yet, coalesce current sub-block with following one */
}
} /* if (nbSeqs > 0) */
/* write last block */
DEBUGLOG(5, "Generate last sub-block: %u sequences remaining", (unsigned)(send - sp));
{ int litEntropyWritten = 0;
int seqEntropyWritten = 0;
size_t litSize = (size_t)(lend - lp);
size_t seqCount = (size_t)(send - sp);
const size_t decompressedSize =
ZSTD_seqDecompressedSize(seqStorePtr, sp, seqCount, litSize, 1);
size_t const cSize = ZSTD_compressSubBlock(&nextCBlock->entropy, entropyMetadata,
sp, seqCount,
lp, litSize,
llCodePtr, mlCodePtr, ofCodePtr,
cctxParams,
op, (size_t)(oend-op),
bmi2, writeLitEntropy, writeSeqEntropy,
&litEntropyWritten, &seqEntropyWritten,
lastBlock);
FORWARD_IF_ERROR(cSize, "ZSTD_compressSubBlock failed");
/* update pointers, the nb of literals borrowed from next sequence must be preserved */
if (cSize > 0 && cSize < decompressedSize) {
DEBUGLOG(5, "Last sub-block compressed %u bytes => %u bytes",
(unsigned)decompressedSize, (unsigned)cSize);
assert(ip + decompressedSize <= iend);
ip += decompressedSize;
lp += litSize;
op += cSize;
llCodePtr += seqCount;
mlCodePtr += seqCount;
ofCodePtr += seqCount;
/* Entropy only needs to be written once */
if (litEntropyWritten) {
writeLitEntropy = 0;
}
if (seqEntropyWritten) {
writeSeqEntropy = 0;
}
sp += seqCount;
}
}
if (writeLitEntropy) {
DEBUGLOG(5, "Literal entropy tables were never written");
ZSTD_memcpy(&nextCBlock->entropy.huf, &prevCBlock->entropy.huf, sizeof(prevCBlock->entropy.huf));
}
if (writeSeqEntropy && ZSTD_needSequenceEntropyTables(&entropyMetadata->fseMetadata)) {
/* If we haven't written our entropy tables, then we've violated our contract and
* must emit an uncompressed block.
*/
DEBUGLOG(5, "Sequence entropy tables were never written => cancel, emit an uncompressed block");
return 0;
}
if (ip < iend) {
/* some data left : last part of the block sent uncompressed */
size_t const rSize = (size_t)((iend - ip));
size_t const cSize = ZSTD_noCompressBlock(op, (size_t)(oend - op), ip, rSize, lastBlock);
DEBUGLOG(5, "Generate last uncompressed sub-block of %u bytes", (unsigned)(rSize));
FORWARD_IF_ERROR(cSize, "ZSTD_noCompressBlock failed");
assert(cSize != 0);
op += cSize;
/* We have to regenerate the repcodes because we've skipped some sequences */
if (sp < send) {
const SeqDef* seq;
Repcodes_t rep;
ZSTD_memcpy(&rep, prevCBlock->rep, sizeof(rep));
for (seq = sstart; seq < sp; ++seq) {
ZSTD_updateRep(rep.rep, seq->offBase, ZSTD_getSequenceLength(seqStorePtr, seq).litLength == 0);
}
ZSTD_memcpy(nextCBlock->rep, &rep, sizeof(rep));
}
}
DEBUGLOG(5, "ZSTD_compressSubBlock_multi compressed all subBlocks: total compressed size = %u",
(unsigned)(op-ostart));
return (size_t)(op-ostart);
}
size_t ZSTD_rust_compressSuperBlock(
const SeqStore_t* seqStore,
const ZSTD_compressedBlockState_t* prevCBlock,
ZSTD_compressedBlockState_t* nextCBlock,
const ZSTD_CCtx_params* cctxParams,
void* workspace, size_t wkspSize,
int bmi2, U32 windowLog, size_t targetCBlockSize,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
U32 lastBlock);
size_t ZSTD_compressSuperBlock(ZSTD_CCtx* zc,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
unsigned lastBlock)
{
ZSTD_entropyCTablesMetadata_t entropyMetadata;
FORWARD_IF_ERROR(ZSTD_buildBlockEntropyStats(&zc->seqStore,
&zc->blockState.prevCBlock->entropy,
&zc->blockState.nextCBlock->entropy,
&zc->appliedParams,
&entropyMetadata,
zc->tmpWorkspace, zc->tmpWkspSize /* statically allocated in resetCCtx */), "");
return ZSTD_compressSubBlock_multi(&zc->seqStore,
return ZSTD_rust_compressSuperBlock(
&zc->seqStore,
zc->blockState.prevCBlock,
zc->blockState.nextCBlock,
&entropyMetadata,
&zc->appliedParams,
zc->tmpWorkspace, zc->tmpWkspSize,
zc->bmi2, zc->appliedParams.cParams.windowLog,
zc->appliedParams.targetCBlockSize,
dst, dstCapacity,
src, srcSize,
zc->bmi2, lastBlock,
zc->tmpWorkspace, zc->tmpWkspSize /* statically allocated in resetCCtx */);
lastBlock);
}
rust/src/lib.rs
+2
View File
@@ -25,6 +25,8 @@ pub mod zstd_common;
pub mod zstd_compress_literals;
#[cfg(feature = "compression")]
pub mod zstd_compress_sequences;
#[cfg(feature = "compression")]
pub mod zstd_compress_superblock;
#[cfg(feature = "decompression")]
pub mod zstd_ddict;
#[cfg(feature = "compression")]
rust/src/zstd_compress_superblock.rs
+1212
View File
@@ -0,0 +1,1212 @@
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
//! Target-size super-block compression.
//!
//! This is the Rust implementation of `zstd_compress_superblock.c`. Its C
//! entry-point shim only extracts fields from the opaque `ZSTD_CCtx`; all
//! sequence partitioning, literal and sequence section writing, entropy
//! fallback, and repcode repair remain here. The leaf layouts below are
//! intentionally kept C-shaped and checked for both supported pointer widths.
use crate::common::{
LL_BITS, LL_DEFAULT_NORM, LL_DEFAULT_NORM_LOG, MAX_LL, MAX_ML, MAX_OFF, MINMATCH, ML_BITS,
ML_DEFAULT_NORM, ML_DEFAULT_NORM_LOG, OF_DEFAULT_NORM, OF_DEFAULT_NORM_LOG,
ZSTD_MAX_FSE_HEADERS_SIZE, ZSTD_MAX_HUF_HEADER_SIZE,
};
use crate::errors::{ERR_isError, ZstdErrorCode, ERROR};
use crate::hist::{HIST_countFast_wksp, HIST_count_wksp};
use crate::huf_compress::{
HUF_compress1X_usingCTable, HUF_compress4X_usingCTable, HUF_estimateCompressedSize,
};
use crate::mem::{MEM_32bits, MEM_writeLE16, MEM_writeLE24, MEM_writeLE32};
use crate::zstd_compress_literals::{
ZSTD_compressRleLiteralsBlock, ZSTD_hufCTables_t, ZSTD_noCompressLiterals,
};
use std::ffi::c_void;
use std::mem::MaybeUninit;
use std::os::raw::{c_int, c_short, c_uint};
use std::ptr;
const SET_BASIC: c_int = 0;
const SET_RLE: c_int = 1;
const SET_COMPRESSED: c_int = 2;
const SET_REPEAT: c_int = 3;
const HUF_FLAGS_BMI2: c_int = 1;
const ZSTD_BLOCK_HEADER_SIZE: usize = 3;
const ZSTD_TARGET_CBLOCK_SIZE_MIN: usize = 1340;
const STREAM_ACCUMULATOR_MIN_32: u32 = 25;
const STREAM_ACCUMULATOR_MIN_64: u32 = 57;
const LONG_NB_SEQ: usize = 0x7f00;
const DEFAULT_MAX_OFF: u32 = 28;
const BYTE_SCALE: usize = 256;
const OFF_CTABLE_SIZE: usize = 1 + (1 << 7) + ((MAX_OFF + 1) * 2);
const ML_CTABLE_SIZE: usize = 1 + (1 << 8) + ((MAX_ML + 1) * 2);
const LL_CTABLE_SIZE: usize = 1 + (1 << 8) + ((MAX_LL + 1) * 2);
/// ABI-compatible `SeqDef` from `zstd_compress_internal.h`.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default)]
struct SeqDef {
offBase: u32,
litLength: u16,
mlBase: u16,
}
/// ABI-compatible `SeqStore_t` leaf layout.
///
/// The C context itself remains opaque. The C shim passes its `seqStore`
/// member directly, so this small, stable hot-path structure is the only
/// sequence storage representation crossing into Rust.
#[repr(C)]
struct SeqStore_t {
sequencesStart: *mut SeqDef,
sequences: *mut SeqDef,
litStart: *mut u8,
lit: *mut u8,
llCode: *mut u8,
mlCode: *mut u8,
ofCode: *mut u8,
maxNbSeq: usize,
maxNbLit: usize,
longLengthType: c_int,
longLengthPos: u32,
}
/// C's `ZSTD_fseCTables_t`. The table element type is `FSE_CTable`, an
/// `unsigned`, and the table lengths are the header macros expanded above.
#[repr(C)]
struct ZSTD_fseCTables_t {
offcodeCTable: [u32; OFF_CTABLE_SIZE],
matchlengthCTable: [u32; ML_CTABLE_SIZE],
litlengthCTable: [u32; LL_CTABLE_SIZE],
offcode_repeatMode: c_int,
matchlength_repeatMode: c_int,
litlength_repeatMode: c_int,
}
#[repr(C)]
struct ZSTD_entropyCTables_t {
huf: ZSTD_hufCTables_t,
fse: ZSTD_fseCTables_t,
}
#[repr(C)]
struct ZSTD_compressedBlockState_t {
entropy: ZSTD_entropyCTables_t,
rep: [u32; 3],
}
#[repr(C)]
struct ZSTD_hufCTablesMetadata_t {
hType: c_int,
hufDesBuffer: [u8; ZSTD_MAX_HUF_HEADER_SIZE],
hufDesSize: usize,
}
#[repr(C)]
struct ZSTD_fseCTablesMetadata_t {
llType: c_int,
ofType: c_int,
mlType: c_int,
fseTablesBuffer: [u8; ZSTD_MAX_FSE_HEADERS_SIZE],
fseTablesSize: usize,
lastCountSize: usize,
}
#[repr(C)]
struct ZSTD_entropyCTablesMetadata_t {
hufMetadata: ZSTD_hufCTablesMetadata_t,
fseMetadata: ZSTD_fseCTablesMetadata_t,
}
unsafe extern "C" {
fn ZSTD_buildBlockEntropyStats(
seq_store: *const SeqStore_t,
prev_entropy: *const ZSTD_entropyCTables_t,
next_entropy: *mut ZSTD_entropyCTables_t,
cctx_params: *const c_void,
entropy_metadata: *mut ZSTD_entropyCTablesMetadata_t,
workspace: *mut c_void,
wksp_size: usize,
) -> usize;
fn ZSTD_encodeSequences(
dst: *mut c_void,
dst_capacity: usize,
ctable_match_length: *const u32,
ml_code_table: *const u8,
ctable_offset_bits: *const u32,
of_code_table: *const u8,
ctable_lit_length: *const u32,
ll_code_table: *const u8,
sequences: *const SeqDef,
nb_seq: usize,
long_offsets: c_int,
bmi2: c_int,
) -> usize;
fn ZSTD_fseBitCost(ctable: *const u32, count: *const u32, max: c_uint) -> usize;
fn ZSTD_crossEntropyCost(
norm: *const c_short,
accuracy_log: c_uint,
count: *const c_uint,
max: c_uint,
) -> usize;
}
#[inline]
fn remaining_capacity(capacity: usize, written: usize) -> Result<usize, usize> {
capacity
.checked_sub(written)
.ok_or_else(|| ERROR(ZstdErrorCode::DstSizeTooSmall))
}
#[inline]
unsafe fn copy_bytes(dst: *mut u8, src: *const u8, size: usize) {
if size != 0 {
unsafe { ptr::copy_nonoverlapping(src, dst, size) };
}
}
#[inline]
unsafe fn sequence_length(seq_store: *const SeqStore_t, sequence: *const SeqDef) -> (usize, usize) {
let sequence_value = unsafe { sequence.read() };
let mut lit_length = sequence_value.litLength as usize;
let mut match_length = sequence_value.mlBase as usize + MINMATCH;
let sequence_index = unsafe { sequence.offset_from((*seq_store).sequencesStart) as usize };
if unsafe { (*seq_store).longLengthPos } == sequence_index as u32 {
match unsafe { (*seq_store).longLengthType } {
1 => lit_length += 1 << 16,
2 => match_length += 1 << 16,
_ => {}
}
}
(lit_length, match_length)
}
#[inline]
unsafe fn no_compress_block(
dst: *mut u8,
dst_capacity: usize,
src: *const u8,
src_size: usize,
last_block: u32,
) -> usize {
let needed = match src_size.checked_add(ZSTD_BLOCK_HEADER_SIZE) {
Some(value) => value,
None => return ERROR(ZstdErrorCode::DstSizeTooSmall),
};
if needed > dst_capacity {
return ERROR(ZstdErrorCode::DstSizeTooSmall);
}
let block_header = last_block.wrapping_add((src_size as u32).wrapping_shl(3));
unsafe {
MEM_writeLE24(dst.cast::<c_void>(), block_header);
copy_bytes(dst.add(ZSTD_BLOCK_HEADER_SIZE), src, src_size);
}
needed
}
#[allow(clippy::too_many_arguments)]
unsafe fn compress_subblock_literal(
huf_table: *const usize,
huf_metadata: *const ZSTD_hufCTablesMetadata_t,
literals: *const u8,
lit_size: usize,
dst: *mut u8,
dst_size: usize,
bmi2: c_int,
write_entropy: bool,
entropy_written: &mut bool,
) -> usize {
let header_slack = if write_entropy { 200 } else { 0 };
let literal_header_size = 3
+ usize::from(lit_size >= 1024 - header_slack)
+ usize::from(lit_size >= 16 * 1024 - header_slack);
let metadata = unsafe { &*huf_metadata };
*entropy_written = false;
if lit_size == 0 || metadata.hType == SET_BASIC {
return unsafe {
ZSTD_noCompressLiterals(
dst.cast::<c_void>(),
dst_size,
literals.cast::<c_void>(),
lit_size,
)
};
}
if metadata.hType == SET_RLE {
return unsafe {
ZSTD_compressRleLiteralsBlock(
dst.cast::<c_void>(),
dst_size,
literals.cast::<c_void>(),
lit_size,
)
};
}
debug_assert!(metadata.hType == SET_COMPRESSED || metadata.hType == SET_REPEAT);
if literal_header_size > dst_size {
return ERROR(ZstdErrorCode::DstSizeTooSmall);
}
let h_type = if write_entropy {
metadata.hType
} else {
SET_REPEAT
};
let mut written = literal_header_size;
let mut compressed_literals_size = 0usize;
if write_entropy && metadata.hType == SET_COMPRESSED {
let remaining = match remaining_capacity(dst_size, written) {
Ok(value) => value,
Err(error) => return error,
};
if metadata.hufDesSize > remaining {
return ERROR(ZstdErrorCode::DstSizeTooSmall);
}
unsafe {
copy_bytes(
dst.add(written),
metadata.hufDesBuffer.as_ptr(),
metadata.hufDesSize,
);
}
written += metadata.hufDesSize;
compressed_literals_size += metadata.hufDesSize;
}
let flags = if bmi2 != 0 { HUF_FLAGS_BMI2 } else { 0 };
let remaining = match remaining_capacity(dst_size, written) {
Ok(value) => value,
Err(error) => return error,
};
let compressed_size = if literal_header_size == 3 {
unsafe {
HUF_compress1X_usingCTable(
dst.add(written).cast::<c_void>(),
remaining,
literals.cast::<c_void>(),
lit_size,
huf_table,
flags,
)
}
} else {
unsafe {
HUF_compress4X_usingCTable(
dst.add(written).cast::<c_void>(),
remaining,
literals.cast::<c_void>(),
lit_size,
huf_table,
flags,
)
}
};
compressed_literals_size = compressed_literals_size.wrapping_add(compressed_size);
if compressed_size == 0 || ERR_isError(compressed_size) {
return 0;
}
written += compressed_size;
if !write_entropy && compressed_literals_size >= lit_size {
return unsafe {
ZSTD_noCompressLiterals(
dst.cast::<c_void>(),
dst_size,
literals.cast::<c_void>(),
lit_size,
)
};
}
let encoded_header_size = 3
+ usize::from(compressed_literals_size >= 1024)
+ usize::from(compressed_literals_size >= 16 * 1024);
if literal_header_size < encoded_header_size {
return unsafe {
ZSTD_noCompressLiterals(
dst.cast::<c_void>(),
dst_size,
literals.cast::<c_void>(),
lit_size,
)
};
}
unsafe {
match literal_header_size {
3 => {
let header = (h_type as u32)
.wrapping_add(((literal_header_size != 3) as u32) << 2)
.wrapping_add((lit_size as u32).wrapping_shl(4))
.wrapping_add((compressed_literals_size as u32).wrapping_shl(14));
MEM_writeLE24(dst.cast::<c_void>(), header);
}
4 => {
let header = (h_type as u32)
.wrapping_add(2 << 2)
.wrapping_add((lit_size as u32).wrapping_shl(4))
.wrapping_add((compressed_literals_size as u32).wrapping_shl(18));
MEM_writeLE32(dst.cast::<c_void>(), header);
}
5 => {
let header = (h_type as u32)
.wrapping_add(3 << 2)
.wrapping_add((lit_size as u32).wrapping_shl(4))
.wrapping_add((compressed_literals_size as u32).wrapping_shl(22));
MEM_writeLE32(dst.cast::<c_void>(), header);
*dst.add(4) = (compressed_literals_size >> 10) as u8;
}
_ => unreachable!("literal header size is three through five bytes"),
}
}
*entropy_written = true;
written
}
#[allow(clippy::too_many_arguments)]
unsafe fn compress_subblock_sequences(
fse_tables: *const ZSTD_fseCTables_t,
fse_metadata: *const ZSTD_fseCTablesMetadata_t,
sequences: *const SeqDef,
nb_seq: usize,
ll_code: *const u8,
ml_code: *const u8,
of_code: *const u8,
window_log: u32,
dst: *mut u8,
dst_capacity: usize,
bmi2: c_int,
write_entropy: bool,
entropy_written: &mut bool,
) -> usize {
*entropy_written = false;
if dst_capacity < 4 {
return ERROR(ZstdErrorCode::DstSizeTooSmall);
}
let mut written = unsafe {
if nb_seq < 128 {
*dst = nb_seq as u8;
1
} else if nb_seq < LONG_NB_SEQ {
*dst = ((nb_seq >> 8) + 0x80) as u8;
*dst.add(1) = nb_seq as u8;
2
} else {
*dst = 0xff;
MEM_writeLE16(dst.add(1).cast::<c_void>(), (nb_seq - LONG_NB_SEQ) as u16);
3
}
};
if nb_seq == 0 {
return written;
}
let sequence_header = written;
written += 1;
let metadata = unsafe { &*fse_metadata };
if write_entropy {
let remaining = match remaining_capacity(dst_capacity, written) {
Ok(value) => value,
Err(error) => return error,
};
if metadata.fseTablesSize > remaining {
return ERROR(ZstdErrorCode::DstSizeTooSmall);
}
unsafe {
*dst.add(sequence_header) = ((metadata.llType as u8) << 6)
.wrapping_add((metadata.ofType as u8) << 4)
.wrapping_add((metadata.mlType as u8) << 2);
copy_bytes(
dst.add(written),
metadata.fseTablesBuffer.as_ptr(),
metadata.fseTablesSize,
);
}
written += metadata.fseTablesSize;
} else {
unsafe { *dst.add(sequence_header) = 0b1111_1100 };
}
let accumulator_min = if MEM_32bits() {
STREAM_ACCUMULATOR_MIN_32
} else {
STREAM_ACCUMULATOR_MIN_64
};
let bitstream_size = unsafe {
ZSTD_encodeSequences(
dst.add(written).cast::<c_void>(),
dst_capacity - written,
(*fse_tables).matchlengthCTable.as_ptr(),
ml_code,
(*fse_tables).offcodeCTable.as_ptr(),
of_code,
(*fse_tables).litlengthCTable.as_ptr(),
ll_code,
sequences,
nb_seq,
c_int::from(window_log > accumulator_min),
bmi2,
)
};
if ERR_isError(bitstream_size) {
return bitstream_size;
}
written += bitstream_size;
if write_entropy
&& metadata.lastCountSize != 0
&& metadata.lastCountSize.saturating_add(bitstream_size) < 4
{
return 0;
}
if written - sequence_header < 4 {
return 0;
}
*entropy_written = true;
written
}
#[allow(clippy::too_many_arguments)]
unsafe fn compress_subblock(
entropy: *const ZSTD_entropyCTables_t,
entropy_metadata: *const ZSTD_entropyCTablesMetadata_t,
sequences: *const SeqDef,
nb_seq: usize,
literals: *const u8,
lit_size: usize,
ll_code: *const u8,
ml_code: *const u8,
of_code: *const u8,
window_log: u32,
dst: *mut u8,
dst_capacity: usize,
bmi2: c_int,
write_lit_entropy: bool,
write_seq_entropy: bool,
lit_entropy_written: &mut bool,
seq_entropy_written: &mut bool,
last_block: u32,
) -> usize {
if dst_capacity < ZSTD_BLOCK_HEADER_SIZE {
return ERROR(ZstdErrorCode::DstSizeTooSmall);
}
let mut written = ZSTD_BLOCK_HEADER_SIZE;
let literal_size = unsafe {
compress_subblock_literal(
(*entropy).huf.CTable.as_ptr(),
ptr::addr_of!((*entropy_metadata).hufMetadata),
literals,
lit_size,
dst.add(written),
dst_capacity - written,
bmi2,
write_lit_entropy,
lit_entropy_written,
)
};
if ERR_isError(literal_size) {
return literal_size;
}
if literal_size == 0 {
return 0;
}
written += literal_size;
let sequence_size = unsafe {
compress_subblock_sequences(
ptr::addr_of!((*entropy).fse),
ptr::addr_of!((*entropy_metadata).fseMetadata),
sequences,
nb_seq,
ll_code,
ml_code,
of_code,
window_log,
dst.add(written),
dst_capacity - written,
bmi2,
write_seq_entropy,
seq_entropy_written,
)
};
if ERR_isError(sequence_size) {
return sequence_size;
}
if sequence_size == 0 {
return 0;
}
written += sequence_size;
let compressed_size = written - ZSTD_BLOCK_HEADER_SIZE;
let block_header = last_block
.wrapping_add(2 << 1)
.wrapping_add((compressed_size as u32).wrapping_shl(3));
unsafe { MEM_writeLE24(dst.cast::<c_void>(), block_header) };
written
}
unsafe fn estimate_subblock_literal(
literals: *const u8,
lit_size: usize,
huf: *const ZSTD_hufCTables_t,
huf_metadata: *const ZSTD_hufCTablesMetadata_t,
workspace: *mut c_void,
wksp_size: usize,
write_entropy: bool,
) -> usize {
let metadata = unsafe { &*huf_metadata };
if metadata.hType == SET_BASIC {
return lit_size;
}
if metadata.hType == SET_RLE {
return 1;
}
let mut max_symbol_value = 255u32;
let largest = unsafe {
HIST_count_wksp(
workspace.cast::<u32>(),
&mut max_symbol_value,
literals.cast::<c_void>(),
lit_size,
workspace,
wksp_size,
)
};
if ERR_isError(largest) {
return lit_size;
}
let mut estimate = unsafe {
HUF_estimateCompressedSize(
(*huf).CTable.as_ptr(),
workspace.cast::<u32>(),
max_symbol_value,
)
};
if write_entropy {
estimate = estimate.wrapping_add(metadata.hufDesSize);
}
estimate.wrapping_add(3)
}
#[allow(clippy::too_many_arguments)]
unsafe fn estimate_subblock_symbol_type(
encoding_type: c_int,
code_table: *const u8,
max_code: u32,
nb_seq: usize,
fse_ctable: *const u32,
additional_bits: Option<&[u8]>,
default_norm: *const i16,
default_norm_log: u32,
default_max: u32,
workspace: *mut c_void,
wksp_size: usize,
) -> usize {
let mut max = max_code;
unsafe {
let _ = HIST_countFast_wksp(
workspace.cast::<u32>(),
&mut max,
code_table.cast::<c_void>(),
nb_seq,
workspace,
wksp_size,
);
}
let mut size_in_bits = match encoding_type {
SET_BASIC if max <= default_max => unsafe {
ZSTD_crossEntropyCost(default_norm, default_norm_log, workspace.cast::<u32>(), max)
},
SET_BASIC => ERROR(ZstdErrorCode::Generic),
SET_RLE => 0,
SET_COMPRESSED | SET_REPEAT => unsafe {
ZSTD_fseBitCost(fse_ctable, workspace.cast::<u32>(), max)
},
_ => ERROR(ZstdErrorCode::Generic),
};
if ERR_isError(size_in_bits) {
return nb_seq.wrapping_mul(10);
}
for index in 0..nb_seq {
let code = unsafe { *code_table.add(index) };
size_in_bits = size_in_bits.wrapping_add(match additional_bits {
Some(bits) => bits[code as usize] as usize,
None => code as usize,
});
}
size_in_bits / 8
}
#[allow(clippy::too_many_arguments)]
unsafe fn estimate_subblock_sequences(
of_code_table: *const u8,
ll_code_table: *const u8,
ml_code_table: *const u8,
nb_seq: usize,
fse_tables: *const ZSTD_fseCTables_t,
fse_metadata: *const ZSTD_fseCTablesMetadata_t,
workspace: *mut c_void,
wksp_size: usize,
write_entropy: bool,
) -> usize {
if nb_seq == 0 {
return 3;
}
let metadata = unsafe { &*fse_metadata };
let tables = unsafe { &*fse_tables };
let mut estimate = unsafe {
estimate_subblock_symbol_type(
metadata.ofType,
of_code_table,
MAX_OFF as u32,
nb_seq,
tables.offcodeCTable.as_ptr(),
None,
OF_DEFAULT_NORM.as_ptr(),
OF_DEFAULT_NORM_LOG,
DEFAULT_MAX_OFF,
workspace,
wksp_size,
)
};
estimate = estimate.wrapping_add(unsafe {
estimate_subblock_symbol_type(
metadata.llType,
ll_code_table,
MAX_LL as u32,
nb_seq,
tables.litlengthCTable.as_ptr(),
Some(&LL_BITS),
LL_DEFAULT_NORM.as_ptr(),
LL_DEFAULT_NORM_LOG,
MAX_LL as u32,
workspace,
wksp_size,
)
});
estimate = estimate.wrapping_add(unsafe {
estimate_subblock_symbol_type(
metadata.mlType,
ml_code_table,
MAX_ML as u32,
nb_seq,
tables.matchlengthCTable.as_ptr(),
Some(&ML_BITS),
ML_DEFAULT_NORM.as_ptr(),
ML_DEFAULT_NORM_LOG,
MAX_ML as u32,
workspace,
wksp_size,
)
});
if write_entropy {
estimate = estimate.wrapping_add(metadata.fseTablesSize);
}
estimate.wrapping_add(3)
}
struct EstimatedBlockSize {
est_lit_size: usize,
est_block_size: usize,
}
#[allow(clippy::too_many_arguments)]
unsafe fn estimate_subblock_size(
literals: *const u8,
lit_size: usize,
of_code_table: *const u8,
ll_code_table: *const u8,
ml_code_table: *const u8,
nb_seq: usize,
entropy: *const ZSTD_entropyCTables_t,
entropy_metadata: *const ZSTD_entropyCTablesMetadata_t,
workspace: *mut c_void,
wksp_size: usize,
write_lit_entropy: bool,
write_seq_entropy: bool,
) -> EstimatedBlockSize {
let est_lit_size = unsafe {
estimate_subblock_literal(
literals,
lit_size,
ptr::addr_of!((*entropy).huf),
ptr::addr_of!((*entropy_metadata).hufMetadata),
workspace,
wksp_size,
write_lit_entropy,
)
};
let est_sequences = unsafe {
estimate_subblock_sequences(
of_code_table,
ll_code_table,
ml_code_table,
nb_seq,
ptr::addr_of!((*entropy).fse),
ptr::addr_of!((*entropy_metadata).fseMetadata),
workspace,
wksp_size,
write_seq_entropy,
)
};
EstimatedBlockSize {
est_lit_size,
est_block_size: est_sequences
.wrapping_add(est_lit_size)
.wrapping_add(ZSTD_BLOCK_HEADER_SIZE),
}
}
#[inline]
unsafe fn need_sequence_entropy_tables(metadata: *const ZSTD_fseCTablesMetadata_t) -> bool {
let metadata = unsafe { &*metadata };
[metadata.llType, metadata.mlType, metadata.ofType]
.iter()
.any(|&encoding_type| encoding_type == SET_COMPRESSED || encoding_type == SET_RLE)
}
unsafe fn count_literals(
seq_store: *const SeqStore_t,
sequences: *const SeqDef,
count: usize,
) -> usize {
let mut total = 0usize;
for index in 0..count {
total = total.wrapping_add(unsafe { sequence_length(seq_store, sequences.add(index)).0 });
}
total
}
unsafe fn sequence_decompressed_size(
seq_store: *const SeqStore_t,
sequences: *const SeqDef,
count: usize,
lit_size: usize,
) -> usize {
let mut match_length_sum = 0usize;
for index in 0..count {
match_length_sum = match_length_sum
.wrapping_add(unsafe { sequence_length(seq_store, sequences.add(index)).1 });
}
match_length_sum.wrapping_add(lit_size)
}
unsafe fn size_block_sequences(
sequences: *const SeqDef,
nb_seq: usize,
target_budget: usize,
avg_lit_cost: usize,
avg_seq_cost: usize,
first_subblock: bool,
) -> usize {
debug_assert!(nb_seq > 0);
let mut budget = if first_subblock {
120usize.wrapping_mul(BYTE_SCALE)
} else {
0
};
let first = unsafe { sequences.read() };
budget = budget
.wrapping_add((first.litLength as usize).wrapping_mul(avg_lit_cost))
.wrapping_add(avg_seq_cost);
if budget > target_budget {
return 1;
}
let mut in_size = first.litLength as usize + first.mlBase as usize + MINMATCH;
for index in 1..nb_seq {
let sequence = unsafe { sequences.add(index).read() };
budget = budget
.wrapping_add((sequence.litLength as usize).wrapping_mul(avg_lit_cost))
.wrapping_add(avg_seq_cost);
in_size = in_size
.wrapping_add(sequence.litLength as usize)
.wrapping_add(sequence.mlBase as usize + MINMATCH);
if budget > target_budget && budget < in_size.wrapping_mul(BYTE_SCALE) {
return index;
}
}
nb_seq
}
#[inline]
fn update_rep(reps: &mut [u32; 3], off_base: u32, literal_length_is_zero: bool) {
if off_base > 3 {
reps[2] = reps[1];
reps[1] = reps[0];
reps[0] = off_base - 3;
return;
}
let rep_code = off_base - 1 + u32::from(literal_length_is_zero);
if rep_code == 0 {
return;
}
let current_offset = if rep_code == 3 {
reps[0].wrapping_sub(1)
} else {
reps[rep_code as usize]
};
reps[2] = if rep_code >= 2 { reps[1] } else { reps[2] };
reps[1] = reps[0];
reps[0] = current_offset;
}
#[allow(clippy::too_many_arguments, clippy::manual_checked_ops)]
unsafe fn compress_subblock_multi(
seq_store: *const SeqStore_t,
prev_cblock: *const ZSTD_compressedBlockState_t,
next_cblock: *mut ZSTD_compressedBlockState_t,
entropy_metadata: *const ZSTD_entropyCTablesMetadata_t,
window_log: u32,
target_cblock_size: usize,
dst: *mut u8,
dst_capacity: usize,
src: *const u8,
src_size: usize,
bmi2: c_int,
last_block: u32,
workspace: *mut c_void,
wksp_size: usize,
) -> usize {
let sequence_start = unsafe { (*seq_store).sequencesStart };
let sequence_end = unsafe { (*seq_store).sequences };
let nb_sequences = unsafe { sequence_end.offset_from(sequence_start) as usize };
let literals_start = unsafe { (*seq_store).litStart };
let literals_end = unsafe { (*seq_store).lit };
let nb_literals = unsafe { literals_end.offset_from(literals_start) as usize };
let mut sequence_index = 0usize;
let mut literal_offset = 0usize;
let mut source_offset = 0usize;
let mut output_offset = 0usize;
let mut write_lit_entropy = unsafe { (*entropy_metadata).hufMetadata.hType == SET_COMPRESSED };
let mut write_seq_entropy = true;
let target_cblock_size = target_cblock_size.max(ZSTD_TARGET_CBLOCK_SIZE_MIN);
if nb_sequences > 0 {
let estimate = unsafe {
estimate_subblock_size(
literals_start,
nb_literals,
(*seq_store).ofCode,
(*seq_store).llCode,
(*seq_store).mlCode,
nb_sequences,
ptr::addr_of!((*next_cblock).entropy),
entropy_metadata,
workspace,
wksp_size,
write_lit_entropy,
write_seq_entropy,
)
};
if estimate.est_block_size > src_size {
return 0;
}
let avg_lit_cost = if nb_literals != 0 {
estimate.est_lit_size.wrapping_mul(BYTE_SCALE) / nb_literals
} else {
BYTE_SCALE
};
let avg_seq_cost = estimate
.est_block_size
.wrapping_sub(estimate.est_lit_size)
.wrapping_mul(BYTE_SCALE)
/ nb_sequences;
let nb_subblocks = ((estimate.est_block_size.wrapping_add(target_cblock_size / 2))
/ target_cblock_size)
.max(1);
let avg_block_budget = estimate.est_block_size.wrapping_mul(BYTE_SCALE) / nb_subblocks;
let block_budget_supp = 0usize;
for subblock_index in 0..nb_subblocks.saturating_sub(1) {
let remaining_sequences = nb_sequences - sequence_index;
let sequence_count = unsafe {
size_block_sequences(
sequence_start.add(sequence_index),
remaining_sequences,
avg_block_budget.wrapping_add(block_budget_supp),
avg_lit_cost,
avg_seq_cost,
subblock_index == 0,
)
};
if sequence_index + sequence_count == nb_sequences {
break;
}
let literal_size = unsafe {
count_literals(
seq_store,
sequence_start.add(sequence_index),
sequence_count,
)
};
let decompressed_size = unsafe {
sequence_decompressed_size(
seq_store,
sequence_start.add(sequence_index),
sequence_count,
literal_size,
)
};
let mut lit_entropy_written = false;
let mut seq_entropy_written = false;
let compressed_size = unsafe {
compress_subblock(
ptr::addr_of!((*next_cblock).entropy),
entropy_metadata,
sequence_start.add(sequence_index),
sequence_count,
literals_start.add(literal_offset),
literal_size,
(*seq_store).llCode.add(sequence_index),
(*seq_store).mlCode.add(sequence_index),
(*seq_store).ofCode.add(sequence_index),
window_log,
dst.add(output_offset),
dst_capacity - output_offset,
bmi2,
write_lit_entropy,
write_seq_entropy,
&mut lit_entropy_written,
&mut seq_entropy_written,
0,
)
};
if ERR_isError(compressed_size) {
return compressed_size;
}
if compressed_size != 0 && compressed_size < decompressed_size {
source_offset = source_offset.wrapping_add(decompressed_size);
literal_offset = literal_offset.wrapping_add(literal_size);
output_offset = output_offset.wrapping_add(compressed_size);
sequence_index += sequence_count;
if lit_entropy_written {
write_lit_entropy = false;
}
if seq_entropy_written {
write_seq_entropy = false;
}
}
}
}
let literal_size = nb_literals - literal_offset;
let sequence_count = nb_sequences - sequence_index;
let decompressed_size = unsafe {
sequence_decompressed_size(
seq_store,
sequence_start.add(sequence_index),
sequence_count,
literal_size,
)
};
let mut lit_entropy_written = false;
let mut seq_entropy_written = false;
let compressed_size = unsafe {
compress_subblock(
ptr::addr_of!((*next_cblock).entropy),
entropy_metadata,
sequence_start.add(sequence_index),
sequence_count,
literals_start.add(literal_offset),
literal_size,
(*seq_store).llCode.add(sequence_index),
(*seq_store).mlCode.add(sequence_index),
(*seq_store).ofCode.add(sequence_index),
window_log,
dst.add(output_offset),
dst_capacity - output_offset,
bmi2,
write_lit_entropy,
write_seq_entropy,
&mut lit_entropy_written,
&mut seq_entropy_written,
last_block,
)
};
if ERR_isError(compressed_size) {
return compressed_size;
}
if compressed_size != 0 && compressed_size < decompressed_size {
source_offset = source_offset.wrapping_add(decompressed_size);
output_offset = output_offset.wrapping_add(compressed_size);
sequence_index += sequence_count;
if lit_entropy_written {
write_lit_entropy = false;
}
if seq_entropy_written {
write_seq_entropy = false;
}
}
if write_lit_entropy {
unsafe {
ptr::copy_nonoverlapping(
ptr::addr_of!((*prev_cblock).entropy.huf),
ptr::addr_of_mut!((*next_cblock).entropy.huf),
1,
);
}
}
if write_seq_entropy
&& unsafe { need_sequence_entropy_tables(ptr::addr_of!((*entropy_metadata).fseMetadata)) }
{
return 0;
}
if source_offset < src_size {
let raw_size = src_size - source_offset;
let remaining = match remaining_capacity(dst_capacity, output_offset) {
Ok(value) => value,
Err(error) => return error,
};
let raw_compressed_size = unsafe {
no_compress_block(
dst.add(output_offset),
remaining,
src.add(source_offset),
raw_size,
last_block,
)
};
if ERR_isError(raw_compressed_size) {
return raw_compressed_size;
}
output_offset += raw_compressed_size;
if sequence_index < nb_sequences {
let mut reps = unsafe { (*prev_cblock).rep };
for index in 0..sequence_index {
let sequence = unsafe { sequence_start.add(index).read() };
let lit_length_is_zero =
unsafe { sequence_length(seq_store, sequence_start.add(index)).0 == 0 };
update_rep(&mut reps, sequence.offBase, lit_length_is_zero);
}
unsafe { (*next_cblock).rep = reps };
}
}
output_offset
}
/// C ABI implementation called by the declaration-only C superblock shim.
///
/// `cctx_params` deliberately remains opaque: only its two required scalar
/// fields are read by the shim, while the existing C entropy builder receives
/// the original pointer unchanged.
#[allow(clippy::too_many_arguments)]
#[no_mangle]
pub unsafe extern "C" fn ZSTD_rust_compressSuperBlock(
seq_store: *const c_void,
prev_cblock: *const c_void,
next_cblock: *mut c_void,
cctx_params: *const c_void,
workspace: *mut c_void,
wksp_size: usize,
bmi2: c_int,
window_log: u32,
target_cblock_size: usize,
dst: *mut c_void,
dst_capacity: usize,
src: *const c_void,
src_size: usize,
last_block: u32,
) -> usize {
let seq_store = seq_store.cast::<SeqStore_t>();
let prev_cblock = prev_cblock.cast::<ZSTD_compressedBlockState_t>();
let next_cblock = next_cblock.cast::<ZSTD_compressedBlockState_t>();
// C only writes the used prefixes of its two metadata byte buffers. Start
// with initialized storage so treating the completed C struct as a Rust
// value never exposes uninitialized array elements.
let mut entropy_metadata = MaybeUninit::<ZSTD_entropyCTablesMetadata_t>::zeroed();
let entropy_result = unsafe {
ZSTD_buildBlockEntropyStats(
seq_store,
ptr::addr_of!((*prev_cblock).entropy),
ptr::addr_of_mut!((*next_cblock).entropy),
cctx_params,
entropy_metadata.as_mut_ptr(),
workspace,
wksp_size,
)
};
if ERR_isError(entropy_result) {
return entropy_result;
}
let entropy_metadata = unsafe { entropy_metadata.assume_init() };
unsafe {
compress_subblock_multi(
seq_store,
prev_cblock,
next_cblock,
&entropy_metadata,
window_log,
target_cblock_size,
dst.cast::<u8>(),
dst_capacity,
src.cast::<u8>(),
src_size,
bmi2,
last_block,
workspace,
wksp_size,
)
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::mem::{align_of, offset_of, size_of};
#[test]
fn c_leaf_layouts_match_supported_abis() {
assert_eq!(size_of::<SeqDef>(), 8);
assert_eq!(align_of::<SeqDef>(), align_of::<u32>());
assert_eq!(offset_of!(SeqStore_t, sequencesStart), 0);
assert_eq!(
offset_of!(SeqStore_t, longLengthPos),
9 * size_of::<usize>() + 4
);
assert_eq!(size_of::<SeqStore_t>(), 9 * size_of::<usize>() + 8);
assert_eq!(size_of::<ZSTD_fseCTables_t>(), 3552);
assert_eq!(offset_of!(ZSTD_compressedBlockState_t, entropy), 0);
assert_eq!(
offset_of!(ZSTD_compressedBlockState_t, rep),
size_of::<ZSTD_entropyCTables_t>()
);
if size_of::<usize>() == 8 {
assert_eq!(size_of::<ZSTD_hufCTablesMetadata_t>(), 144);
assert_eq!(size_of::<ZSTD_fseCTablesMetadata_t>(), 168);
assert_eq!(size_of::<ZSTD_entropyCTablesMetadata_t>(), 312);
assert_eq!(size_of::<ZSTD_entropyCTables_t>(), 5616);
assert_eq!(size_of::<ZSTD_compressedBlockState_t>(), 5632);
} else {
assert_eq!(size_of::<ZSTD_hufCTablesMetadata_t>(), 136);
assert_eq!(size_of::<ZSTD_fseCTablesMetadata_t>(), 156);
assert_eq!(size_of::<ZSTD_entropyCTablesMetadata_t>(), 292);
assert_eq!(size_of::<ZSTD_entropyCTables_t>(), 4584);
assert_eq!(size_of::<ZSTD_compressedBlockState_t>(), 4596);
}
}
#[test]
fn repcode_updates_match_the_c_sum_type_rules() {
let mut reps = [1, 4, 8];
update_rep(&mut reps, 10, false);
assert_eq!(reps, [7, 1, 4]);
update_rep(&mut reps, 1, true);
assert_eq!(reps, [1, 7, 4]);
update_rep(&mut reps, 2, false);
assert_eq!(reps, [7, 1, 4]);
update_rep(&mut reps, 3, false);
assert_eq!(reps, [4, 7, 1]);
}
}