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zstd_decompress_block.c
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zstd_decompress_block.c
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/*
* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
* You may select, at your option, one of the above-listed licenses.
*/
/* zstd_decompress_block :
* this module takes care of decompressing _compressed_ block */
/*-*******************************************************
* Dependencies
*********************************************************/
#include <string.h> /* memcpy, memmove, memset */
#include "compiler.h" /* prefetch */
#include "cpu.h" /* bmi2 */
#include "mem.h" /* low level memory routines */
#define FSE_STATIC_LINKING_ONLY
#include "fse.h"
#define HUF_STATIC_LINKING_ONLY
#include "huf.h"
#include "zstd_internal.h"
#include "zstd_decompress_internal.h" /* ZSTD_DCtx */
#include "zstd_ddict.h" /* ZSTD_DDictDictContent */
#include "zstd_decompress_block.h"
/*_*******************************************************
* Macros
**********************************************************/
/* These two optional macros force the use one way or another of the two
* ZSTD_decompressSequences implementations. You can't force in both directions
* at the same time.
*/
#if defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
#error "Cannot force the use of the short and the long ZSTD_decompressSequences variants!"
#endif
/*_*******************************************************
* Memory operations
**********************************************************/
static void ZSTD_copy4(void* dst, const void* src) { memcpy(dst, src, 4); }
/*-*************************************************************
* Block decoding
***************************************************************/
/*! ZSTD_getcBlockSize() :
* Provides the size of compressed block from block header `src` */
size_t ZSTD_getcBlockSize(const void* src, size_t srcSize,
blockProperties_t* bpPtr)
{
if (srcSize < ZSTD_blockHeaderSize) return ERROR(srcSize_wrong);
{ U32 const cBlockHeader = MEM_readLE24(src);
U32 const cSize = cBlockHeader >> 3;
bpPtr->lastBlock = cBlockHeader & 1;
bpPtr->blockType = (blockType_e)((cBlockHeader >> 1) & 3);
bpPtr->origSize = cSize; /* only useful for RLE */
if (bpPtr->blockType == bt_rle) return 1;
if (bpPtr->blockType == bt_reserved) return ERROR(corruption_detected);
return cSize;
}
}
/* Hidden declaration for fullbench */
size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
const void* src, size_t srcSize);
/*! ZSTD_decodeLiteralsBlock() :
* @return : nb of bytes read from src (< srcSize )
* note : symbol not declared but exposed for fullbench */
size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
const void* src, size_t srcSize) /* note : srcSize < BLOCKSIZE */
{
if (srcSize < MIN_CBLOCK_SIZE) return ERROR(corruption_detected);
{ const BYTE* const istart = (const BYTE*) src;
symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3);
switch(litEncType)
{
case set_repeat:
if (dctx->litEntropy==0) return ERROR(dictionary_corrupted);
/* fall-through */
case set_compressed:
if (srcSize < 5) return ERROR(corruption_detected); /* srcSize >= MIN_CBLOCK_SIZE == 3; here we need up to 5 for case 3 */
{ size_t lhSize, litSize, litCSize;
U32 singleStream=0;
U32 const lhlCode = (istart[0] >> 2) & 3;
U32 const lhc = MEM_readLE32(istart);
size_t hufSuccess;
switch(lhlCode)
{
case 0: case 1: default: /* note : default is impossible, since lhlCode into [0..3] */
/* 2 - 2 - 10 - 10 */
singleStream = !lhlCode;
lhSize = 3;
litSize = (lhc >> 4) & 0x3FF;
litCSize = (lhc >> 14) & 0x3FF;
break;
case 2:
/* 2 - 2 - 14 - 14 */
lhSize = 4;
litSize = (lhc >> 4) & 0x3FFF;
litCSize = lhc >> 18;
break;
case 3:
/* 2 - 2 - 18 - 18 */
lhSize = 5;
litSize = (lhc >> 4) & 0x3FFFF;
litCSize = (lhc >> 22) + (istart[4] << 10);
break;
}
if (litSize > ZSTD_BLOCKSIZE_MAX) return ERROR(corruption_detected);
if (litCSize + lhSize > srcSize) return ERROR(corruption_detected);
/* prefetch huffman table if cold */
if (dctx->ddictIsCold && (litSize > 768 /* heuristic */)) {
PREFETCH_AREA(dctx->HUFptr, sizeof(dctx->entropy.hufTable));
}
if (litEncType==set_repeat) {
if (singleStream) {
hufSuccess = HUF_decompress1X_usingDTable_bmi2(
dctx->litBuffer, litSize, istart+lhSize, litCSize,
dctx->HUFptr, dctx->bmi2);
} else {
hufSuccess = HUF_decompress4X_usingDTable_bmi2(
dctx->litBuffer, litSize, istart+lhSize, litCSize,
dctx->HUFptr, dctx->bmi2);
}
} else {
if (singleStream) {
#if defined(HUF_FORCE_DECOMPRESS_X2)
hufSuccess = HUF_decompress1X_DCtx_wksp(
dctx->entropy.hufTable, dctx->litBuffer, litSize,
istart+lhSize, litCSize, dctx->workspace,
sizeof(dctx->workspace));
#else
hufSuccess = HUF_decompress1X1_DCtx_wksp_bmi2(
dctx->entropy.hufTable, dctx->litBuffer, litSize,
istart+lhSize, litCSize, dctx->workspace,
sizeof(dctx->workspace), dctx->bmi2);
#endif
} else {
hufSuccess = HUF_decompress4X_hufOnly_wksp_bmi2(
dctx->entropy.hufTable, dctx->litBuffer, litSize,
istart+lhSize, litCSize, dctx->workspace,
sizeof(dctx->workspace), dctx->bmi2);
}
}
if (HUF_isError(hufSuccess)) return ERROR(corruption_detected);
dctx->litPtr = dctx->litBuffer;
dctx->litSize = litSize;
dctx->litEntropy = 1;
if (litEncType==set_compressed) dctx->HUFptr = dctx->entropy.hufTable;
memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH);
return litCSize + lhSize;
}
case set_basic:
{ size_t litSize, lhSize;
U32 const lhlCode = ((istart[0]) >> 2) & 3;
switch(lhlCode)
{
case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */
lhSize = 1;
litSize = istart[0] >> 3;
break;
case 1:
lhSize = 2;
litSize = MEM_readLE16(istart) >> 4;
break;
case 3:
lhSize = 3;
litSize = MEM_readLE24(istart) >> 4;
break;
}
if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) { /* risk reading beyond src buffer with wildcopy */
if (litSize+lhSize > srcSize) return ERROR(corruption_detected);
memcpy(dctx->litBuffer, istart+lhSize, litSize);
dctx->litPtr = dctx->litBuffer;
dctx->litSize = litSize;
memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH);
return lhSize+litSize;
}
/* direct reference into compressed stream */
dctx->litPtr = istart+lhSize;
dctx->litSize = litSize;
return lhSize+litSize;
}
case set_rle:
{ U32 const lhlCode = ((istart[0]) >> 2) & 3;
size_t litSize, lhSize;
switch(lhlCode)
{
case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */
lhSize = 1;
litSize = istart[0] >> 3;
break;
case 1:
lhSize = 2;
litSize = MEM_readLE16(istart) >> 4;
break;
case 3:
lhSize = 3;
litSize = MEM_readLE24(istart) >> 4;
if (srcSize<4) return ERROR(corruption_detected); /* srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4 */
break;
}
if (litSize > ZSTD_BLOCKSIZE_MAX) return ERROR(corruption_detected);
memset(dctx->litBuffer, istart[lhSize], litSize + WILDCOPY_OVERLENGTH);
dctx->litPtr = dctx->litBuffer;
dctx->litSize = litSize;
return lhSize+1;
}
default:
return ERROR(corruption_detected); /* impossible */
}
}
}
/* Default FSE distribution tables.
* These are pre-calculated FSE decoding tables using default distributions as defined in specification :
* https://github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#default-distributions
* They were generated programmatically with following method :
* - start from default distributions, present in /lib/common/zstd_internal.h
* - generate tables normally, using ZSTD_buildFSETable()
* - printout the content of tables
* - pretify output, report below, test with fuzzer to ensure it's correct */
/* Default FSE distribution table for Literal Lengths */
static const ZSTD_seqSymbol LL_defaultDTable[(1<<LL_DEFAULTNORMLOG)+1] = {
{ 1, 1, 1, LL_DEFAULTNORMLOG}, /* header : fastMode, tableLog */
/* nextState, nbAddBits, nbBits, baseVal */
{ 0, 0, 4, 0}, { 16, 0, 4, 0},
{ 32, 0, 5, 1}, { 0, 0, 5, 3},
{ 0, 0, 5, 4}, { 0, 0, 5, 6},
{ 0, 0, 5, 7}, { 0, 0, 5, 9},
{ 0, 0, 5, 10}, { 0, 0, 5, 12},
{ 0, 0, 6, 14}, { 0, 1, 5, 16},
{ 0, 1, 5, 20}, { 0, 1, 5, 22},
{ 0, 2, 5, 28}, { 0, 3, 5, 32},
{ 0, 4, 5, 48}, { 32, 6, 5, 64},
{ 0, 7, 5, 128}, { 0, 8, 6, 256},
{ 0, 10, 6, 1024}, { 0, 12, 6, 4096},
{ 32, 0, 4, 0}, { 0, 0, 4, 1},
{ 0, 0, 5, 2}, { 32, 0, 5, 4},
{ 0, 0, 5, 5}, { 32, 0, 5, 7},
{ 0, 0, 5, 8}, { 32, 0, 5, 10},
{ 0, 0, 5, 11}, { 0, 0, 6, 13},
{ 32, 1, 5, 16}, { 0, 1, 5, 18},
{ 32, 1, 5, 22}, { 0, 2, 5, 24},
{ 32, 3, 5, 32}, { 0, 3, 5, 40},
{ 0, 6, 4, 64}, { 16, 6, 4, 64},
{ 32, 7, 5, 128}, { 0, 9, 6, 512},
{ 0, 11, 6, 2048}, { 48, 0, 4, 0},
{ 16, 0, 4, 1}, { 32, 0, 5, 2},
{ 32, 0, 5, 3}, { 32, 0, 5, 5},
{ 32, 0, 5, 6}, { 32, 0, 5, 8},
{ 32, 0, 5, 9}, { 32, 0, 5, 11},
{ 32, 0, 5, 12}, { 0, 0, 6, 15},
{ 32, 1, 5, 18}, { 32, 1, 5, 20},
{ 32, 2, 5, 24}, { 32, 2, 5, 28},
{ 32, 3, 5, 40}, { 32, 4, 5, 48},
{ 0, 16, 6,65536}, { 0, 15, 6,32768},
{ 0, 14, 6,16384}, { 0, 13, 6, 8192},
}; /* LL_defaultDTable */
/* Default FSE distribution table for Offset Codes */
static const ZSTD_seqSymbol OF_defaultDTable[(1<<OF_DEFAULTNORMLOG)+1] = {
{ 1, 1, 1, OF_DEFAULTNORMLOG}, /* header : fastMode, tableLog */
/* nextState, nbAddBits, nbBits, baseVal */
{ 0, 0, 5, 0}, { 0, 6, 4, 61},
{ 0, 9, 5, 509}, { 0, 15, 5,32765},
{ 0, 21, 5,2097149}, { 0, 3, 5, 5},
{ 0, 7, 4, 125}, { 0, 12, 5, 4093},
{ 0, 18, 5,262141}, { 0, 23, 5,8388605},
{ 0, 5, 5, 29}, { 0, 8, 4, 253},
{ 0, 14, 5,16381}, { 0, 20, 5,1048573},
{ 0, 2, 5, 1}, { 16, 7, 4, 125},
{ 0, 11, 5, 2045}, { 0, 17, 5,131069},
{ 0, 22, 5,4194301}, { 0, 4, 5, 13},
{ 16, 8, 4, 253}, { 0, 13, 5, 8189},
{ 0, 19, 5,524285}, { 0, 1, 5, 1},
{ 16, 6, 4, 61}, { 0, 10, 5, 1021},
{ 0, 16, 5,65533}, { 0, 28, 5,268435453},
{ 0, 27, 5,134217725}, { 0, 26, 5,67108861},
{ 0, 25, 5,33554429}, { 0, 24, 5,16777213},
}; /* OF_defaultDTable */
/* Default FSE distribution table for Match Lengths */
static const ZSTD_seqSymbol ML_defaultDTable[(1<<ML_DEFAULTNORMLOG)+1] = {
{ 1, 1, 1, ML_DEFAULTNORMLOG}, /* header : fastMode, tableLog */
/* nextState, nbAddBits, nbBits, baseVal */
{ 0, 0, 6, 3}, { 0, 0, 4, 4},
{ 32, 0, 5, 5}, { 0, 0, 5, 6},
{ 0, 0, 5, 8}, { 0, 0, 5, 9},
{ 0, 0, 5, 11}, { 0, 0, 6, 13},
{ 0, 0, 6, 16}, { 0, 0, 6, 19},
{ 0, 0, 6, 22}, { 0, 0, 6, 25},
{ 0, 0, 6, 28}, { 0, 0, 6, 31},
{ 0, 0, 6, 34}, { 0, 1, 6, 37},
{ 0, 1, 6, 41}, { 0, 2, 6, 47},
{ 0, 3, 6, 59}, { 0, 4, 6, 83},
{ 0, 7, 6, 131}, { 0, 9, 6, 515},
{ 16, 0, 4, 4}, { 0, 0, 4, 5},
{ 32, 0, 5, 6}, { 0, 0, 5, 7},
{ 32, 0, 5, 9}, { 0, 0, 5, 10},
{ 0, 0, 6, 12}, { 0, 0, 6, 15},
{ 0, 0, 6, 18}, { 0, 0, 6, 21},
{ 0, 0, 6, 24}, { 0, 0, 6, 27},
{ 0, 0, 6, 30}, { 0, 0, 6, 33},
{ 0, 1, 6, 35}, { 0, 1, 6, 39},
{ 0, 2, 6, 43}, { 0, 3, 6, 51},
{ 0, 4, 6, 67}, { 0, 5, 6, 99},
{ 0, 8, 6, 259}, { 32, 0, 4, 4},
{ 48, 0, 4, 4}, { 16, 0, 4, 5},
{ 32, 0, 5, 7}, { 32, 0, 5, 8},
{ 32, 0, 5, 10}, { 32, 0, 5, 11},
{ 0, 0, 6, 14}, { 0, 0, 6, 17},
{ 0, 0, 6, 20}, { 0, 0, 6, 23},
{ 0, 0, 6, 26}, { 0, 0, 6, 29},
{ 0, 0, 6, 32}, { 0, 16, 6,65539},
{ 0, 15, 6,32771}, { 0, 14, 6,16387},
{ 0, 13, 6, 8195}, { 0, 12, 6, 4099},
{ 0, 11, 6, 2051}, { 0, 10, 6, 1027},
}; /* ML_defaultDTable */
static void ZSTD_buildSeqTable_rle(ZSTD_seqSymbol* dt, U32 baseValue, U32 nbAddBits)
{
void* ptr = dt;
ZSTD_seqSymbol_header* const DTableH = (ZSTD_seqSymbol_header*)ptr;
ZSTD_seqSymbol* const cell = dt + 1;
DTableH->tableLog = 0;
DTableH->fastMode = 0;
cell->nbBits = 0;
cell->nextState = 0;
assert(nbAddBits < 255);
cell->nbAdditionalBits = (BYTE)nbAddBits;
cell->baseValue = baseValue;
}
/* ZSTD_buildFSETable() :
* generate FSE decoding table for one symbol (ll, ml or off)
* cannot fail if input is valid =>
* all inputs are presumed validated at this stage */
void
ZSTD_buildFSETable(ZSTD_seqSymbol* dt,
const short* normalizedCounter, unsigned maxSymbolValue,
const U32* baseValue, const U32* nbAdditionalBits,
unsigned tableLog)
{
ZSTD_seqSymbol* const tableDecode = dt+1;
U16 symbolNext[MaxSeq+1];
U32 const maxSV1 = maxSymbolValue + 1;
U32 const tableSize = 1 << tableLog;
U32 highThreshold = tableSize-1;
/* Sanity Checks */
assert(maxSymbolValue <= MaxSeq);
assert(tableLog <= MaxFSELog);
/* Init, lay down lowprob symbols */
{ ZSTD_seqSymbol_header DTableH;
DTableH.tableLog = tableLog;
DTableH.fastMode = 1;
{ S16 const largeLimit= (S16)(1 << (tableLog-1));
U32 s;
for (s=0; s<maxSV1; s++) {
if (normalizedCounter[s]==-1) {
tableDecode[highThreshold--].baseValue = s;
symbolNext[s] = 1;
} else {
if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
symbolNext[s] = normalizedCounter[s];
} } }
memcpy(dt, &DTableH, sizeof(DTableH));
}
/* Spread symbols */
{ U32 const tableMask = tableSize-1;
U32 const step = FSE_TABLESTEP(tableSize);
U32 s, position = 0;
for (s=0; s<maxSV1; s++) {
int i;
for (i=0; i<normalizedCounter[s]; i++) {
tableDecode[position].baseValue = s;
position = (position + step) & tableMask;
while (position > highThreshold) position = (position + step) & tableMask; /* lowprob area */
} }
assert(position == 0); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
}
/* Build Decoding table */
{ U32 u;
for (u=0; u<tableSize; u++) {
U32 const symbol = tableDecode[u].baseValue;
U32 const nextState = symbolNext[symbol]++;
tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) );
tableDecode[u].nextState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
assert(nbAdditionalBits[symbol] < 255);
tableDecode[u].nbAdditionalBits = (BYTE)nbAdditionalBits[symbol];
tableDecode[u].baseValue = baseValue[symbol];
} }
}
/*! ZSTD_buildSeqTable() :
* @return : nb bytes read from src,
* or an error code if it fails */
static size_t ZSTD_buildSeqTable(ZSTD_seqSymbol* DTableSpace, const ZSTD_seqSymbol** DTablePtr,
symbolEncodingType_e type, unsigned max, U32 maxLog,
const void* src, size_t srcSize,
const U32* baseValue, const U32* nbAdditionalBits,
const ZSTD_seqSymbol* defaultTable, U32 flagRepeatTable,
int ddictIsCold, int nbSeq)
{
switch(type)
{
case set_rle :
if (!srcSize) return ERROR(srcSize_wrong);
if ( (*(const BYTE*)src) > max) return ERROR(corruption_detected);
{ U32 const symbol = *(const BYTE*)src;
U32 const baseline = baseValue[symbol];
U32 const nbBits = nbAdditionalBits[symbol];
ZSTD_buildSeqTable_rle(DTableSpace, baseline, nbBits);
}
*DTablePtr = DTableSpace;
return 1;
case set_basic :
*DTablePtr = defaultTable;
return 0;
case set_repeat:
if (!flagRepeatTable) return ERROR(corruption_detected);
/* prefetch FSE table if used */
if (ddictIsCold && (nbSeq > 24 /* heuristic */)) {
const void* const pStart = *DTablePtr;
size_t const pSize = sizeof(ZSTD_seqSymbol) * (SEQSYMBOL_TABLE_SIZE(maxLog));
PREFETCH_AREA(pStart, pSize);
}
return 0;
case set_compressed :
{ unsigned tableLog;
S16 norm[MaxSeq+1];
size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize);
if (FSE_isError(headerSize)) return ERROR(corruption_detected);
if (tableLog > maxLog) return ERROR(corruption_detected);
ZSTD_buildFSETable(DTableSpace, norm, max, baseValue, nbAdditionalBits, tableLog);
*DTablePtr = DTableSpace;
return headerSize;
}
default : /* impossible */
assert(0);
return ERROR(GENERIC);
}
}
size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr,
const void* src, size_t srcSize)
{
const BYTE* const istart = (const BYTE* const)src;
const BYTE* const iend = istart + srcSize;
const BYTE* ip = istart;
int nbSeq;
DEBUGLOG(5, "ZSTD_decodeSeqHeaders");
/* check */
if (srcSize < MIN_SEQUENCES_SIZE) return ERROR(srcSize_wrong);
/* SeqHead */
nbSeq = *ip++;
if (!nbSeq) {
*nbSeqPtr=0;
if (srcSize != 1) return ERROR(srcSize_wrong);
return 1;
}
if (nbSeq > 0x7F) {
if (nbSeq == 0xFF) {
if (ip+2 > iend) return ERROR(srcSize_wrong);
nbSeq = MEM_readLE16(ip) + LONGNBSEQ, ip+=2;
} else {
if (ip >= iend) return ERROR(srcSize_wrong);
nbSeq = ((nbSeq-0x80)<<8) + *ip++;
}
}
*nbSeqPtr = nbSeq;
/* FSE table descriptors */
if (ip+4 > iend) return ERROR(srcSize_wrong); /* minimum possible size */
{ symbolEncodingType_e const LLtype = (symbolEncodingType_e)(*ip >> 6);
symbolEncodingType_e const OFtype = (symbolEncodingType_e)((*ip >> 4) & 3);
symbolEncodingType_e const MLtype = (symbolEncodingType_e)((*ip >> 2) & 3);
ip++;
/* Build DTables */
{ size_t const llhSize = ZSTD_buildSeqTable(dctx->entropy.LLTable, &dctx->LLTptr,
LLtype, MaxLL, LLFSELog,
ip, iend-ip,
LL_base, LL_bits,
LL_defaultDTable, dctx->fseEntropy,
dctx->ddictIsCold, nbSeq);
if (ZSTD_isError(llhSize)) return ERROR(corruption_detected);
ip += llhSize;
}
{ size_t const ofhSize = ZSTD_buildSeqTable(dctx->entropy.OFTable, &dctx->OFTptr,
OFtype, MaxOff, OffFSELog,
ip, iend-ip,
OF_base, OF_bits,
OF_defaultDTable, dctx->fseEntropy,
dctx->ddictIsCold, nbSeq);
if (ZSTD_isError(ofhSize)) return ERROR(corruption_detected);
ip += ofhSize;
}
{ size_t const mlhSize = ZSTD_buildSeqTable(dctx->entropy.MLTable, &dctx->MLTptr,
MLtype, MaxML, MLFSELog,
ip, iend-ip,
ML_base, ML_bits,
ML_defaultDTable, dctx->fseEntropy,
dctx->ddictIsCold, nbSeq);
if (ZSTD_isError(mlhSize)) return ERROR(corruption_detected);
ip += mlhSize;
}
}
return ip-istart;
}
typedef struct {
size_t litLength;
size_t matchLength;
size_t offset;
const BYTE* match;
} seq_t;
typedef struct {
size_t state;
const ZSTD_seqSymbol* table;
} ZSTD_fseState;
typedef struct {
BIT_DStream_t DStream;
ZSTD_fseState stateLL;
ZSTD_fseState stateOffb;
ZSTD_fseState stateML;
size_t prevOffset[ZSTD_REP_NUM];
const BYTE* prefixStart;
const BYTE* dictEnd;
size_t pos;
} seqState_t;
/* ZSTD_execSequenceLast7():
* exceptional case : decompress a match starting within last 7 bytes of output buffer.
* requires more careful checks, to ensure there is no overflow.
* performance does not matter though.
* note : this case is supposed to be never generated "naturally" by reference encoder,
* since in most cases it needs at least 8 bytes to look for a match.
* but it's allowed by the specification. */
FORCE_NOINLINE
size_t ZSTD_execSequenceLast7(BYTE* op,
BYTE* const oend, seq_t sequence,
const BYTE** litPtr, const BYTE* const litLimit,
const BYTE* const base, const BYTE* const vBase, const BYTE* const dictEnd)
{
BYTE* const oLitEnd = op + sequence.litLength;
size_t const sequenceLength = sequence.litLength + sequence.matchLength;
BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */
const BYTE* const iLitEnd = *litPtr + sequence.litLength;
const BYTE* match = oLitEnd - sequence.offset;
/* check */
if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must fit within dstBuffer */
if (iLitEnd > litLimit) return ERROR(corruption_detected); /* try to read beyond literal buffer */
/* copy literals */
while (op < oLitEnd) *op++ = *(*litPtr)++;
/* copy Match */
if (sequence.offset > (size_t)(oLitEnd - base)) {
/* offset beyond prefix */
if (sequence.offset > (size_t)(oLitEnd - vBase)) return ERROR(corruption_detected);
match = dictEnd - (base-match);
if (match + sequence.matchLength <= dictEnd) {
memmove(oLitEnd, match, sequence.matchLength);
return sequenceLength;
}
/* span extDict & currentPrefixSegment */
{ size_t const length1 = dictEnd - match;
memmove(oLitEnd, match, length1);
op = oLitEnd + length1;
sequence.matchLength -= length1;
match = base;
} }
while (op < oMatchEnd) *op++ = *match++;
return sequenceLength;
}
HINT_INLINE
size_t ZSTD_execSequence(BYTE* op,
BYTE* const oend, seq_t sequence,
const BYTE** litPtr, const BYTE* const litLimit,
const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
{
BYTE* const oLitEnd = op + sequence.litLength;
size_t const sequenceLength = sequence.litLength + sequence.matchLength;
BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */
BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
const BYTE* const iLitEnd = *litPtr + sequence.litLength;
const BYTE* match = oLitEnd - sequence.offset;
/* check */
if (oMatchEnd>oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */
if (iLitEnd > litLimit) return ERROR(corruption_detected); /* over-read beyond lit buffer */
if (oLitEnd>oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd);
/* copy Literals */
ZSTD_copy8(op, *litPtr);
if (sequence.litLength > 8)
ZSTD_wildcopy(op+8, (*litPtr)+8, sequence.litLength - 8); /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */
op = oLitEnd;
*litPtr = iLitEnd; /* update for next sequence */
/* copy Match */
if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
/* offset beyond prefix -> go into extDict */
if (sequence.offset > (size_t)(oLitEnd - virtualStart))
return ERROR(corruption_detected);
match = dictEnd + (match - prefixStart);
if (match + sequence.matchLength <= dictEnd) {
memmove(oLitEnd, match, sequence.matchLength);
return sequenceLength;
}
/* span extDict & currentPrefixSegment */
{ size_t const length1 = dictEnd - match;
memmove(oLitEnd, match, length1);
op = oLitEnd + length1;
sequence.matchLength -= length1;
match = prefixStart;
if (op > oend_w || sequence.matchLength < MINMATCH) {
U32 i;
for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i];
return sequenceLength;
}
} }
/* Requirement: op <= oend_w && sequence.matchLength >= MINMATCH */
/* match within prefix */
if (sequence.offset < 8) {
/* close range match, overlap */
static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */
static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */
int const sub2 = dec64table[sequence.offset];
op[0] = match[0];
op[1] = match[1];
op[2] = match[2];
op[3] = match[3];
match += dec32table[sequence.offset];
ZSTD_copy4(op+4, match);
match -= sub2;
} else {
ZSTD_copy8(op, match);
}
op += 8; match += 8;
if (oMatchEnd > oend-(16-MINMATCH)) {
if (op < oend_w) {
ZSTD_wildcopy(op, match, oend_w - op);
match += oend_w - op;
op = oend_w;
}
while (op < oMatchEnd) *op++ = *match++;
} else {
ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8); /* works even if matchLength < 8 */
}
return sequenceLength;
}
HINT_INLINE
size_t ZSTD_execSequenceLong(BYTE* op,
BYTE* const oend, seq_t sequence,
const BYTE** litPtr, const BYTE* const litLimit,
const BYTE* const prefixStart, const BYTE* const dictStart, const BYTE* const dictEnd)
{
BYTE* const oLitEnd = op + sequence.litLength;
size_t const sequenceLength = sequence.litLength + sequence.matchLength;
BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */
BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
const BYTE* const iLitEnd = *litPtr + sequence.litLength;
const BYTE* match = sequence.match;
/* check */
if (oMatchEnd > oend) return ERROR(dstSize_tooSmall); /* last match must start at a minimum distance of WILDCOPY_OVERLENGTH from oend */
if (iLitEnd > litLimit) return ERROR(corruption_detected); /* over-read beyond lit buffer */
if (oLitEnd > oend_w) return ZSTD_execSequenceLast7(op, oend, sequence, litPtr, litLimit, prefixStart, dictStart, dictEnd);
/* copy Literals */
ZSTD_copy8(op, *litPtr); /* note : op <= oLitEnd <= oend_w == oend - 8 */
if (sequence.litLength > 8)
ZSTD_wildcopy(op+8, (*litPtr)+8, sequence.litLength - 8); /* note : since oLitEnd <= oend-WILDCOPY_OVERLENGTH, no risk of overwrite beyond oend */
op = oLitEnd;
*litPtr = iLitEnd; /* update for next sequence */
/* copy Match */
if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
/* offset beyond prefix */
if (sequence.offset > (size_t)(oLitEnd - dictStart)) return ERROR(corruption_detected);
if (match + sequence.matchLength <= dictEnd) {
memmove(oLitEnd, match, sequence.matchLength);
return sequenceLength;
}
/* span extDict & currentPrefixSegment */
{ size_t const length1 = dictEnd - match;
memmove(oLitEnd, match, length1);
op = oLitEnd + length1;
sequence.matchLength -= length1;
match = prefixStart;
if (op > oend_w || sequence.matchLength < MINMATCH) {
U32 i;
for (i = 0; i < sequence.matchLength; ++i) op[i] = match[i];
return sequenceLength;
}
} }
assert(op <= oend_w);
assert(sequence.matchLength >= MINMATCH);
/* match within prefix */
if (sequence.offset < 8) {
/* close range match, overlap */
static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */
static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */
int const sub2 = dec64table[sequence.offset];
op[0] = match[0];
op[1] = match[1];
op[2] = match[2];
op[3] = match[3];
match += dec32table[sequence.offset];
ZSTD_copy4(op+4, match);
match -= sub2;
} else {
ZSTD_copy8(op, match);
}
op += 8; match += 8;
if (oMatchEnd > oend-(16-MINMATCH)) {
if (op < oend_w) {
ZSTD_wildcopy(op, match, oend_w - op);
match += oend_w - op;
op = oend_w;
}
while (op < oMatchEnd) *op++ = *match++;
} else {
ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8); /* works even if matchLength < 8 */
}
return sequenceLength;
}
static void
ZSTD_initFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, const ZSTD_seqSymbol* dt)
{
const void* ptr = dt;
const ZSTD_seqSymbol_header* const DTableH = (const ZSTD_seqSymbol_header*)ptr;
DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog);
DEBUGLOG(6, "ZSTD_initFseState : val=%u using %u bits",
(U32)DStatePtr->state, DTableH->tableLog);
BIT_reloadDStream(bitD);
DStatePtr->table = dt + 1;
}
FORCE_INLINE_TEMPLATE void
ZSTD_updateFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD)
{
ZSTD_seqSymbol const DInfo = DStatePtr->table[DStatePtr->state];
U32 const nbBits = DInfo.nbBits;
size_t const lowBits = BIT_readBits(bitD, nbBits);
DStatePtr->state = DInfo.nextState + lowBits;
}
/* We need to add at most (ZSTD_WINDOWLOG_MAX_32 - 1) bits to read the maximum
* offset bits. But we can only read at most (STREAM_ACCUMULATOR_MIN_32 - 1)
* bits before reloading. This value is the maximum number of bytes we read
* after reloading when we are decoding long offets.
*/
#define LONG_OFFSETS_MAX_EXTRA_BITS_32 \
(ZSTD_WINDOWLOG_MAX_32 > STREAM_ACCUMULATOR_MIN_32 \
? ZSTD_WINDOWLOG_MAX_32 - STREAM_ACCUMULATOR_MIN_32 \
: 0)
typedef enum { ZSTD_lo_isRegularOffset, ZSTD_lo_isLongOffset=1 } ZSTD_longOffset_e;
#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
FORCE_INLINE_TEMPLATE seq_t
ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets)
{
seq_t seq;
U32 const llBits = seqState->stateLL.table[seqState->stateLL.state].nbAdditionalBits;
U32 const mlBits = seqState->stateML.table[seqState->stateML.state].nbAdditionalBits;
U32 const ofBits = seqState->stateOffb.table[seqState->stateOffb.state].nbAdditionalBits;
U32 const totalBits = llBits+mlBits+ofBits;
U32 const llBase = seqState->stateLL.table[seqState->stateLL.state].baseValue;
U32 const mlBase = seqState->stateML.table[seqState->stateML.state].baseValue;
U32 const ofBase = seqState->stateOffb.table[seqState->stateOffb.state].baseValue;
/* sequence */
{ size_t offset;
if (!ofBits)
offset = 0;
else {
ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1);
ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5);
assert(ofBits <= MaxOff);
if (MEM_32bits() && longOffsets && (ofBits >= STREAM_ACCUMULATOR_MIN_32)) {
U32 const extraBits = ofBits - MIN(ofBits, 32 - seqState->DStream.bitsConsumed);
offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits);
BIT_reloadDStream(&seqState->DStream);
if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits);
assert(extraBits <= LONG_OFFSETS_MAX_EXTRA_BITS_32); /* to avoid another reload */
} else {
offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits/*>0*/); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */
if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
}
}
if (ofBits <= 1) {
offset += (llBase==0);
if (offset) {
size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */
if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
seqState->prevOffset[1] = seqState->prevOffset[0];
seqState->prevOffset[0] = offset = temp;
} else { /* offset == 0 */
offset = seqState->prevOffset[0];
}
} else {
seqState->prevOffset[2] = seqState->prevOffset[1];
seqState->prevOffset[1] = seqState->prevOffset[0];
seqState->prevOffset[0] = offset;
}
seq.offset = offset;
}
seq.matchLength = mlBase
+ ((mlBits>0) ? BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/) : 0); /* <= 16 bits */
if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32))
BIT_reloadDStream(&seqState->DStream);
if (MEM_64bits() && (totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog)))
BIT_reloadDStream(&seqState->DStream);
/* Ensure there are enough bits to read the rest of data in 64-bit mode. */
ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64);
seq.litLength = llBase
+ ((llBits>0) ? BIT_readBitsFast(&seqState->DStream, llBits/*>0*/) : 0); /* <= 16 bits */
if (MEM_32bits())
BIT_reloadDStream(&seqState->DStream);
DEBUGLOG(6, "seq: litL=%u, matchL=%u, offset=%u",
(U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset);
/* ANS state update */
ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream); /* <= 9 bits */
ZSTD_updateFseState(&seqState->stateML, &seqState->DStream); /* <= 9 bits */
if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */
ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream); /* <= 8 bits */
return seq;
}
FORCE_INLINE_TEMPLATE size_t
ZSTD_decompressSequences_body( ZSTD_DCtx* dctx,
void* dst, size_t maxDstSize,
const void* seqStart, size_t seqSize, int nbSeq,
const ZSTD_longOffset_e isLongOffset)
{
const BYTE* ip = (const BYTE*)seqStart;
const BYTE* const iend = ip + seqSize;
BYTE* const ostart = (BYTE* const)dst;
BYTE* const oend = ostart + maxDstSize;
BYTE* op = ostart;
const BYTE* litPtr = dctx->litPtr;
const BYTE* const litEnd = litPtr + dctx->litSize;
const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart);
const BYTE* const vBase = (const BYTE*) (dctx->virtualStart);
const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
DEBUGLOG(5, "ZSTD_decompressSequences_body");
/* Regen sequences */
if (nbSeq) {
seqState_t seqState;
dctx->fseEntropy = 1;
{ U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
CHECK_E(BIT_initDStream(&seqState.DStream, ip, iend-ip), corruption_detected);
ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; ) {
nbSeq--;
{ seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd);
DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
op += oneSeqSize;
} }
/* check if reached exact end */
DEBUGLOG(5, "ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i", nbSeq);
if (nbSeq) return ERROR(corruption_detected);
/* save reps for next block */
{ U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
}
/* last literal segment */
{ size_t const lastLLSize = litEnd - litPtr;
if (lastLLSize > (size_t)(oend-op)) return ERROR(dstSize_tooSmall);
memcpy(op, litPtr, lastLLSize);
op += lastLLSize;
}
return op-ostart;
}
static size_t
ZSTD_decompressSequences_default(ZSTD_DCtx* dctx,
void* dst, size_t maxDstSize,
const void* seqStart, size_t seqSize, int nbSeq,
const ZSTD_longOffset_e isLongOffset)
{
return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset);
}
#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
FORCE_INLINE_TEMPLATE seq_t
ZSTD_decodeSequenceLong(seqState_t* seqState, ZSTD_longOffset_e const longOffsets)
{
seq_t seq;
U32 const llBits = seqState->stateLL.table[seqState->stateLL.state].nbAdditionalBits;
U32 const mlBits = seqState->stateML.table[seqState->stateML.state].nbAdditionalBits;
U32 const ofBits = seqState->stateOffb.table[seqState->stateOffb.state].nbAdditionalBits;
U32 const totalBits = llBits+mlBits+ofBits;
U32 const llBase = seqState->stateLL.table[seqState->stateLL.state].baseValue;
U32 const mlBase = seqState->stateML.table[seqState->stateML.state].baseValue;
U32 const ofBase = seqState->stateOffb.table[seqState->stateOffb.state].baseValue;
/* sequence */
{ size_t offset;
if (!ofBits)
offset = 0;
else {
ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1);
ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5);
assert(ofBits <= MaxOff);
if (MEM_32bits() && longOffsets) {
U32 const extraBits = ofBits - MIN(ofBits, STREAM_ACCUMULATOR_MIN_32-1);
offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits);
if (MEM_32bits() || extraBits) BIT_reloadDStream(&seqState->DStream);
if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits);
} else {
offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */
if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
}
}
if (ofBits <= 1) {
offset += (llBase==0);
if (offset) {
size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */
if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
seqState->prevOffset[1] = seqState->prevOffset[0];
seqState->prevOffset[0] = offset = temp;
} else {
offset = seqState->prevOffset[0];
}
} else {