diff options
Diffstat (limited to 'lib/zstd/decompress/zstd_decompress_block.c')
| -rw-r--r-- | lib/zstd/decompress/zstd_decompress_block.c | 2072 |
1 files changed, 2072 insertions, 0 deletions
diff --git a/lib/zstd/decompress/zstd_decompress_block.c b/lib/zstd/decompress/zstd_decompress_block.c new file mode 100644 index 000000000000..c1913b8e7c89 --- /dev/null +++ b/lib/zstd/decompress/zstd_decompress_block.c @@ -0,0 +1,2072 @@ +/* + * Copyright (c) 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 "../common/zstd_deps.h" /* ZSTD_memcpy, ZSTD_memmove, ZSTD_memset */ +#include "../common/compiler.h" /* prefetch */ +#include "../common/cpu.h" /* bmi2 */ +#include "../common/mem.h" /* low level memory routines */ +#define FSE_STATIC_LINKING_ONLY +#include "../common/fse.h" +#define HUF_STATIC_LINKING_ONLY +#include "../common/huf.h" +#include "../common/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) { ZSTD_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) +{ + RETURN_ERROR_IF(srcSize < ZSTD_blockHeaderSize, 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; + RETURN_ERROR_IF(bpPtr->blockType == bt_reserved, corruption_detected, ""); + return cSize; + } +} + +/* Allocate buffer for literals, either overlapping current dst, or split between dst and litExtraBuffer, or stored entirely within litExtraBuffer */ +static void ZSTD_allocateLiteralsBuffer(ZSTD_DCtx* dctx, void* const dst, const size_t dstCapacity, const size_t litSize, + const streaming_operation streaming, const size_t expectedWriteSize, const unsigned splitImmediately) +{ + if (streaming == not_streaming && dstCapacity > ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH + litSize + WILDCOPY_OVERLENGTH) + { + /* room for litbuffer to fit without read faulting */ + dctx->litBuffer = (BYTE*)dst + ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH; + dctx->litBufferEnd = dctx->litBuffer + litSize; + dctx->litBufferLocation = ZSTD_in_dst; + } + else if (litSize > ZSTD_LITBUFFEREXTRASIZE) + { + /* won't fit in litExtraBuffer, so it will be split between end of dst and extra buffer */ + if (splitImmediately) { + /* won't fit in litExtraBuffer, so it will be split between end of dst and extra buffer */ + dctx->litBuffer = (BYTE*)dst + expectedWriteSize - litSize + ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH; + dctx->litBufferEnd = dctx->litBuffer + litSize - ZSTD_LITBUFFEREXTRASIZE; + } + else { + /* initially this will be stored entirely in dst during huffman decoding, it will partially shifted to litExtraBuffer after */ + dctx->litBuffer = (BYTE*)dst + expectedWriteSize - litSize; + dctx->litBufferEnd = (BYTE*)dst + expectedWriteSize; + } + dctx->litBufferLocation = ZSTD_split; + } + else + { + /* fits entirely within litExtraBuffer, so no split is necessary */ + dctx->litBuffer = dctx->litExtraBuffer; + dctx->litBufferEnd = dctx->litBuffer + litSize; + dctx->litBufferLocation = ZSTD_not_in_dst; + } +} + +/* Hidden declaration for fullbench */ +size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx, + const void* src, size_t srcSize, + void* dst, size_t dstCapacity, const streaming_operation streaming); +/*! ZSTD_decodeLiteralsBlock() : + * Where it is possible to do so without being stomped by the output during decompression, the literals block will be stored + * in the dstBuffer. If there is room to do so, it will be stored in full in the excess dst space after where the current + * block will be output. Otherwise it will be stored at the end of the current dst blockspace, with a small portion being + * stored in dctx->litExtraBuffer to help keep it "ahead" of the current output write. + * + * @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 */ + void* dst, size_t dstCapacity, const streaming_operation streaming) +{ + DEBUGLOG(5, "ZSTD_decodeLiteralsBlock"); + RETURN_ERROR_IF(srcSize < MIN_CBLOCK_SIZE, corruption_detected, ""); + + { const BYTE* const istart = (const BYTE*) src; + symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3); + + switch(litEncType) + { + case set_repeat: + DEBUGLOG(5, "set_repeat flag : re-using stats from previous compressed literals block"); + RETURN_ERROR_IF(dctx->litEntropy==0, dictionary_corrupted, ""); + ZSTD_FALLTHROUGH; + + case set_compressed: + RETURN_ERROR_IF(srcSize < 5, 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; + size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity); + 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) + ((size_t)istart[4] << 10); + break; + } + RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled"); + RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, ""); + RETURN_ERROR_IF(litCSize + lhSize > srcSize, corruption_detected, ""); + RETURN_ERROR_IF(expectedWriteSize < litSize , dstSize_tooSmall, ""); + ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 0); + + /* 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, ZSTD_DCtx_get_bmi2(dctx)); + } else { + hufSuccess = HUF_decompress4X_usingDTable_bmi2( + dctx->litBuffer, litSize, istart+lhSize, litCSize, + dctx->HUFptr, ZSTD_DCtx_get_bmi2(dctx)); + } + } 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), ZSTD_DCtx_get_bmi2(dctx)); +#endif + } else { + hufSuccess = HUF_decompress4X_hufOnly_wksp_bmi2( + dctx->entropy.hufTable, dctx->litBuffer, litSize, + istart+lhSize, litCSize, dctx->workspace, + sizeof(dctx->workspace), ZSTD_DCtx_get_bmi2(dctx)); + } + } + if (dctx->litBufferLocation == ZSTD_split) + { + ZSTD_memcpy(dctx->litExtraBuffer, dctx->litBufferEnd - ZSTD_LITBUFFEREXTRASIZE, ZSTD_LITBUFFEREXTRASIZE); + ZSTD_memmove(dctx->litBuffer + ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH, dctx->litBuffer, litSize - ZSTD_LITBUFFEREXTRASIZE); + dctx->litBuffer += ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH; + dctx->litBufferEnd -= WILDCOPY_OVERLENGTH; + } + + RETURN_ERROR_IF(HUF_isError(hufSuccess), corruption_detected, ""); + + dctx->litPtr = dctx->litBuffer; + dctx->litSize = litSize; + dctx->litEntropy = 1; + if (litEncType==set_compressed) dctx->HUFptr = dctx->entropy.hufTable; + return litCSize + lhSize; + } + + case set_basic: + { size_t litSize, lhSize; + U32 const lhlCode = ((istart[0]) >> 2) & 3; + size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity); + 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; + } + + RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled"); + RETURN_ERROR_IF(expectedWriteSize < litSize, dstSize_tooSmall, ""); + ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 1); + if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) { /* risk reading beyond src buffer with wildcopy */ + RETURN_ERROR_IF(litSize+lhSize > srcSize, corruption_detected, ""); + if (dctx->litBufferLocation == ZSTD_split) + { + ZSTD_memcpy(dctx->litBuffer, istart + lhSize, litSize - ZSTD_LITBUFFEREXTRASIZE); + ZSTD_memcpy(dctx->litExtraBuffer, istart + lhSize + litSize - ZSTD_LITBUFFEREXTRASIZE, ZSTD_LITBUFFEREXTRASIZE); + } + else + { + ZSTD_memcpy(dctx->litBuffer, istart + lhSize, litSize); + } + dctx->litPtr = dctx->litBuffer; + dctx->litSize = litSize; + return lhSize+litSize; + } + /* direct reference into compressed stream */ + dctx->litPtr = istart+lhSize; + dctx->litSize = litSize; + dctx->litBufferEnd = dctx->litPtr + litSize; + dctx->litBufferLocation = ZSTD_not_in_dst; + return lhSize+litSize; + } + + case set_rle: + { U32 const lhlCode = ((istart[0]) >> 2) & 3; + size_t litSize, lhSize; + size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity); + 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; + RETURN_ERROR_IF(srcSize<4, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4"); + break; + } + RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled"); + RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, ""); + RETURN_ERROR_IF(expectedWriteSize < litSize, dstSize_tooSmall, ""); + ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 1); + if (dctx->litBufferLocation == ZSTD_split) + { + ZSTD_memset(dctx->litBuffer, istart[lhSize], litSize - ZSTD_LITBUFFEREXTRASIZE); + ZSTD_memset(dctx->litExtraBuffer, istart[lhSize], ZSTD_LITBUFFEREXTRASIZE); + } + else + { + ZSTD_memset(dctx->litBuffer, istart[lhSize], litSize); + } + 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/release/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, U8 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 = 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 */ +FORCE_INLINE_TEMPLATE +void ZSTD_buildFSETable_body(ZSTD_seqSymbol* dt, + const short* normalizedCounter, unsigned maxSymbolValue, + const U32* baseValue, const U8* nbAdditionalBits, + unsigned tableLog, void* wksp, size_t wkspSize) +{ + ZSTD_seqSymbol* const tableDecode = dt+1; + U32 const maxSV1 = maxSymbolValue + 1; + U32 const tableSize = 1 << tableLog; + + U16* symbolNext = (U16*)wksp; + BYTE* spread = (BYTE*)(symbolNext + MaxSeq + 1); + U32 highThreshold = tableSize - 1; + + + /* Sanity Checks */ + assert(maxSymbolValue <= MaxSeq); + assert(tableLog <= MaxFSELog); + assert(wkspSize >= ZSTD_BUILD_FSE_TABLE_WKSP_SIZE); + (void)wkspSize; + /* 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; + assert(normalizedCounter[s]>=0); + symbolNext[s] = (U16)normalizedCounter[s]; + } } } + ZSTD_memcpy(dt, &DTableH, sizeof(DTableH)); + } + + /* Spread symbols */ + assert(tableSize <= 512); + /* Specialized symbol spreading for the case when there are + * no low probability (-1 count) symbols. When compressing + * small blocks we avoid low probability symbols to hit this + * case, since header decoding speed matters more. + */ + if (highThreshold == tableSize - 1) { + size_t const tableMask = tableSize-1; + size_t const step = FSE_TABLESTEP(tableSize); + /* First lay down the symbols in order. + * We use a uint64_t to lay down 8 bytes at a time. This reduces branch + * misses since small blocks generally have small table logs, so nearly + * all symbols have counts <= 8. We ensure we have 8 bytes at the end of + * our buffer to handle the over-write. + */ + { + U64 const add = 0x0101010101010101ull; + size_t pos = 0; + U64 sv = 0; + U32 s; + for (s=0; s<maxSV1; ++s, sv += add) { + int i; + int const n = normalizedCounter[s]; + MEM_write64(spread + pos, sv); + for (i = 8; i < n; i += 8) { + MEM_write64(spread + pos + i, sv); + } + pos += n; + } + } + /* Now we spread those positions across the table. + * The benefit of doing it in two stages is that we avoid the the + * variable size inner loop, which caused lots of branch misses. + * Now we can run through all the positions without any branch misses. + * We unroll the loop twice, since that is what emperically worked best. + */ + { + size_t position = 0; + size_t s; + size_t const unroll = 2; + assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */ + for (s = 0; s < (size_t)tableSize; s += unroll) { + size_t u; + for (u = 0; u < unroll; ++u) { + size_t const uPosition = (position + (u * step)) & tableMask; + tableDecode[uPosition].baseValue = spread[s + u]; + } + position = (position + (unroll * step)) & tableMask; + } + assert(position == 0); + } + } else { + U32 const tableMask = tableSize-1; + U32 const step = FSE_TABLESTEP(tableSize); + U32 s, position = 0; + for (s=0; s<maxSV1; s++) { + int i; + int const n = normalizedCounter[s]; + for (i=0; i<n; 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 = nbAdditionalBits[symbol]; + tableDecode[u].baseValue = baseValue[symbol]; + } + } +} + +/* Avoids the FORCE_INLINE of the _body() function. */ +static void ZSTD_buildFSETable_body_default(ZSTD_seqSymbol* dt, + const short* normalizedCounter, unsigned maxSymbolValue, + const U32* baseValue, const U8* nbAdditionalBits, + unsigned tableLog, void* wksp, size_t wkspSize) +{ + ZSTD_buildFSETable_body(dt, normalizedCounter, maxSymbolValue, + baseValue, nbAdditionalBits, tableLog, wksp, wkspSize); +} + +#if DYNAMIC_BMI2 +BMI2_TARGET_ATTRIBUTE static void ZSTD_buildFSETable_body_bmi2(ZSTD_seqSymbol* dt, + const short* normalizedCounter, unsigned maxSymbolValue, + const U32* baseValue, const U8* nbAdditionalBits, + unsigned tableLog, void* wksp, size_t wkspSize) +{ + ZSTD_buildFSETable_body(dt, normalizedCounter, maxSymbolValue, + baseValue, nbAdditionalBits, tableLog, wksp, wkspSize); +} +#endif + +void ZSTD_buildFSETable(ZSTD_seqSymbol* dt, + const short* normalizedCounter, unsigned maxSymbolValue, + const U32* baseValue, const U8* nbAdditionalBits, + unsigned tableLog, void* wksp, size_t wkspSize, int bmi2) +{ +#if DYNAMIC_BMI2 + if (bmi2) { + ZSTD_buildFSETable_body_bmi2(dt, normalizedCounter, maxSymbolValue, + baseValue, nbAdditionalBits, tableLog, wksp, wkspSize); + return; + } +#endif + (void)bmi2; + ZSTD_buildFSETable_body_default(dt, normalizedCounter, maxSymbolValue, + baseValue, nbAdditionalBits, tableLog, wksp, wkspSize); +} + + +/*! 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 U8* nbAdditionalBits, + const ZSTD_seqSymbol* defaultTable, U32 flagRepeatTable, + int ddictIsCold, int nbSeq, U32* wksp, size_t wkspSize, + int bmi2) +{ + switch(type) + { + case set_rle : + RETURN_ERROR_IF(!srcSize, srcSize_wrong, ""); + RETURN_ERROR_IF((*(const BYTE*)src) > max, corruption_detected, ""); + { U32 const symbol = *(const BYTE*)src; + U32 const baseline = baseValue[symbol]; + U8 const nbBits = nbAdditionalBits[symbol]; + ZSTD_buildSeqTable_rle(DTableSpace, baseline, nbBits); + } + *DTablePtr = DTableSpace; + return 1; + case set_basic : + *DTablePtr = defaultTable; + return 0; + case set_repeat: + RETURN_ERROR_IF(!flagRepeatTable, 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); + RETURN_ERROR_IF(FSE_isError(headerSize), corruption_detected, ""); + RETURN_ERROR_IF(tableLog > maxLog, corruption_detected, ""); + ZSTD_buildFSETable(DTableSpace, norm, max, baseValue, nbAdditionalBits, tableLog, wksp, wkspSize, bmi2); + *DTablePtr = DTableSpace; + return headerSize; + } + default : + assert(0); + RETURN_ERROR(GENERIC, "impossible"); + } +} + +size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr, + const void* src, size_t srcSize) +{ + const BYTE* const istart = (const BYTE*)src; + const BYTE* const iend = istart + srcSize; + const BYTE* ip = istart; + int nbSeq; + DEBUGLOG(5, "ZSTD_decodeSeqHeaders"); + + /* check */ + RETURN_ERROR_IF(srcSize < MIN_SEQUENCES_SIZE, srcSize_wrong, ""); + + /* SeqHead */ + nbSeq = *ip++; + if (!nbSeq) { + *nbSeqPtr=0; + RETURN_ERROR_IF(srcSize != 1, srcSize_wrong, ""); + return 1; + } + if (nbSeq > 0x7F) { + if (nbSeq == 0xFF) { + RETURN_ERROR_IF(ip+2 > iend, srcSize_wrong, ""); + nbSeq = MEM_readLE16(ip) + LONGNBSEQ; + ip+=2; + } else { + RETURN_ERROR_IF(ip >= iend, srcSize_wrong, ""); + nbSeq = ((nbSeq-0x80)<<8) + *ip++; + } + } + *nbSeqPtr = nbSeq; + + /* FSE table descriptors */ + RETURN_ERROR_IF(ip+1 > iend, srcSize_wrong, ""); /* minimum possible size: 1 byte for symbol encoding types */ + { 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, + dctx->workspace, sizeof(dctx->workspace), + ZSTD_DCtx_get_bmi2(dctx)); + RETURN_ERROR_IF(ZSTD_isError(llhSize), corruption_detected, "ZSTD_buildSeqTable failed"); + 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, + dctx->workspace, sizeof(dctx->workspace), + ZSTD_DCtx_get_bmi2(dctx)); + RETURN_ERROR_IF(ZSTD_isError(ofhSize), corruption_detected, "ZSTD_buildSeqTable failed"); + 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, + dctx->workspace, sizeof(dctx->workspace), + ZSTD_DCtx_get_bmi2(dctx)); + RETURN_ERROR_IF(ZSTD_isError(mlhSize), corruption_detected, "ZSTD_buildSeqTable failed"); + ip += mlhSize; + } + } + + return ip-istart; +} + + +typedef struct { + size_t litLength; + size_t matchLength; + size_t offset; +} 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]; +} seqState_t; + +/*! ZSTD_overlapCopy8() : + * Copies 8 bytes from ip to op and updates op and ip where ip <= op. + * If the offset is < 8 then the offset is spread to at least 8 bytes. + * + * Precondition: *ip <= *op + * Postcondition: *op - *op >= 8 + */ +HINT_INLINE void ZSTD_overlapCopy8(BYTE** op, BYTE const** ip, size_t offset) { + assert(*ip <= *op); + if (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[offset]; + (*op)[0] = (*ip)[0]; + (*op)[1] = (*ip)[1]; + (*op)[2] = (*ip)[2]; + (*op)[3] = (*ip)[3]; + *ip += dec32table[offset]; + ZSTD_copy4(*op+4, *ip); + *ip -= sub2; + } else { + ZSTD_copy8(*op, *ip); + } + *ip += 8; + *op += 8; + assert(*op - *ip >= 8); +} + +/*! ZSTD_safecopy() : + * Specialized version of memcpy() that is allowed to READ up to WILDCOPY_OVERLENGTH past the input buffer + * and write up to 16 bytes past oend_w (op >= oend_w is allowed). + * This function is only called in the uncommon case where the sequence is near the end of the block. It + * should be fast for a single long sequence, but can be slow for several short sequences. + * + * @param ovtype controls the overlap detection + * - ZSTD_no_overlap: The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart. + * - ZSTD_overlap_src_before_dst: The src and dst may overlap and may be any distance apart. + * The src buffer must be before the dst buffer. + */ +static void ZSTD_safecopy(BYTE* op, const BYTE* const oend_w, BYTE const* ip, ptrdiff_t length, ZSTD_overlap_e ovtype) { + ptrdiff_t const diff = op - ip; + BYTE* const oend = op + length; + + assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8 || op >= oend_w)) || + (ovtype == ZSTD_overlap_src_before_dst && diff >= 0)); + + if (length < 8) { + /* Handle short lengths. */ + while (op < oend) *op++ = *ip++; + return; + } + if (ovtype == ZSTD_overlap_src_before_dst) { + /* Copy 8 bytes and ensure the offset >= 8 when there can be overlap. */ + assert(length >= 8); + ZSTD_overlapCopy8(&op, &ip, diff); + length -= 8; + assert(op - ip >= 8); + assert(op <= oend); + } + + if (oend <= oend_w) { + /* No risk of overwrite. */ + ZSTD_wildcopy(op, ip, length, ovtype); + return; + } + if (op <= oend_w) { + /* Wildcopy until we get close to the end. */ + assert(oend > oend_w); + ZSTD_wildcopy(op, ip, oend_w - op, ovtype); + ip += oend_w - op; + op += oend_w - op; + } + /* Handle the leftovers. */ + while (op < oend) *op++ = *ip++; +} + +/* ZSTD_safecopyDstBeforeSrc(): + * This version allows overlap with dst before src, or handles the non-overlap case with dst after src + * Kept separate from more common ZSTD_safecopy case to avoid performance impact to the safecopy common case */ +static void ZSTD_safecopyDstBeforeSrc(BYTE* op, BYTE const* ip, ptrdiff_t length) { + ptrdiff_t const diff = op - ip; + BYTE* const oend = op + length; + + if (length < 8 || diff > -8) { + /* Handle short lengths, close overlaps, and dst not before src. */ + while (op < oend) *op++ = *ip++; + return; + } + + if (op <= oend - WILDCOPY_OVERLENGTH && diff < -WILDCOPY_VECLEN) { + ZSTD_wildcopy(op, ip, oend - WILDCOPY_OVERLENGTH - op, ZSTD_no_overlap); + ip += oend - WILDCOPY_OVERLENGTH - op; + op += oend - WILDCOPY_OVERLENGTH - op; + } + + /* Handle the leftovers. */ + while (op < oend) *op++ = *ip++; +} + +/* ZSTD_execSequenceEnd(): + * This version handles cases that are near the end of the output buffer. It requires + * more careful checks to make sure there is no overflow. By separating out these hard + * and unlikely cases, we can speed up the common cases. + * + * NOTE: This function needs to be fast for a single long sequence, but doesn't need + * to be optimized for many small sequences, since those fall into ZSTD_execSequence(). + */ +FORCE_NOINLINE +size_t ZSTD_execSequenceEnd(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; + const BYTE* const iLitEnd = *litPtr + sequence.litLength; + const BYTE* match = oLitEnd - sequence.offset; + BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; + + /* bounds checks : careful of address space overflow in 32-bit mode */ + RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer"); + RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer"); + assert(op < op + sequenceLength); + assert(oLitEnd < op + sequenceLength); + + /* copy literals */ + ZSTD_safecopy(op, oend_w, *litPtr, sequence.litLength, ZSTD_no_overlap); + op = oLitEnd; + *litPtr = iLitEnd; + + /* copy Match */ + if (sequence.offset > (size_t)(oLitEnd - prefixStart)) { + /* offset beyond prefix */ + RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, ""); + match = dictEnd - (prefixStart - match); + if (match + sequence.matchLength <= dictEnd) { + ZSTD_memmove(oLitEnd, match, sequence.matchLength); + return sequenceLength; + } + /* span extDict & currentPrefixSegment */ + { size_t const length1 = dictEnd - match; + ZSTD_memmove(oLitEnd, match, length1); + op = oLitEnd + length1; + sequence.matchLength -= length1; + match = prefixStart; + } + } + ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst); + return sequenceLength; +} + +/* ZSTD_execSequenceEndSplitLitBuffer(): + * This version is intended to be used during instances where the litBuffer is still split. It is kept separate to avoid performance impact for the good case. + */ +FORCE_NOINLINE +size_t ZSTD_execSequenceEndSplitLitBuffer(BYTE* op, + BYTE* const oend, const BYTE* const oend_w, 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; + const BYTE* const iLitEnd = *litPtr + sequence.litLength; + const BYTE* match = oLitEnd - sequence.offset; + + + /* bounds checks : careful of address space overflow in 32-bit mode */ + RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer"); + RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer"); + assert(op < op + sequenceLength); + assert(oLitEnd < op + sequenceLength); + + /* copy literals */ + RETURN_ERROR_IF(op > *litPtr && op < *litPtr + sequence.litLength, dstSize_tooSmall, "output should not catch up to and overwrite literal buffer"); + ZSTD_safecopyDstBeforeSrc(op, *litPtr, sequence.litLength); + op = oLitEnd; + *litPtr = iLitEnd; + + /* copy Match */ + if (sequence.offset > (size_t)(oLitEnd - prefixStart)) { + /* offset beyond prefix */ + RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, ""); + match = dictEnd - (prefixStart - match); + if (match + sequence.matchLength <= dictEnd) { + ZSTD_memmove(oLitEnd, match, sequence.matchLength); + return sequenceLength; + } + /* span extDict & currentPrefixSegment */ + { size_t const length1 = dictEnd - match; + ZSTD_memmove(oLitEnd, match, length1); + op = oLitEnd + length1; + sequence.matchLength -= length1; + match = prefixStart; + } + } + ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst); + 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; /* risk : address space underflow on oend=NULL */ + const BYTE* const iLitEnd = *litPtr + sequence.litLength; + const BYTE* match = oLitEnd - sequence.offset; + + assert(op != NULL /* Precondition */); + assert(oend_w < oend /* No underflow */); + /* Handle edge cases in a slow path: + * - Read beyond end of literals + * - Match end is within WILDCOPY_OVERLIMIT of oend + * - 32-bit mode and the match length overflows + */ + if (UNLIKELY( + iLitEnd > litLimit || + oMatchEnd > oend_w || + (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH))) + return ZSTD_execSequenceEnd(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd); + + /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */ + assert(op <= oLitEnd /* No overflow */); + assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */); + assert(oMatchEnd <= oend /* No underflow */); + assert(iLitEnd <= litLimit /* Literal length is in bounds */); + assert(oLitEnd <= oend_w /* Can wildcopy literals */); + assert(oMatchEnd <= oend_w /* Can wildcopy matches */); + + /* Copy Literals: + * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9. + * We likely don't need the full 32-byte wildcopy. + */ + assert(WILDCOPY_OVERLENGTH >= 16); + ZSTD_copy16(op, (*litPtr)); + if (UNLIKELY(sequence.litLength > 16)) { + ZSTD_wildcopy(op + 16, (*litPtr) + 16, sequence.litLength - 16, ZSTD_no_overlap); + } + op = oLitEnd; + *litPtr = iLitEnd; /* update for next sequence */ + + /* Copy Match */ + if (sequence.offset > (size_t)(oLitEnd - prefixStart)) { + /* offset beyond prefix -> go into extDict */ + RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, ""); + match = dictEnd + (match - prefixStart); + if (match + sequence.matchLength <= dictEnd) { + ZSTD_memmove(oLitEnd, match, sequence.matchLength); + return sequenceLength; + } + /* span extDict & currentPrefixSegment */ + { size_t const length1 = dictEnd - match; + ZSTD_memmove(oLitEnd, match, length1); + op = oLitEnd + length1; + sequence.matchLength -= length1; + match = prefixStart; + } + } + /* Match within prefix of 1 or more bytes */ + assert(op <= oMatchEnd); + assert(oMatchEnd <= oend_w); + assert(match >= prefixStart); + assert(sequence.matchLength >= 1); + + /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy + * without overlap checking. + */ + if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) { + /* We bet on a full wildcopy for matches, since we expect matches to be + * longer than literals (in general). In silesia, ~10% of matches are longer + * than 16 bytes. + */ + ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap); + return sequenceLength; + } + assert(sequence.offset < WILDCOPY_VECLEN); + + /* Copy 8 bytes and spread the offset to be >= 8. */ + ZSTD_overlapCopy8(&op, &match, sequence.offset); + + /* If the match length is > 8 bytes, then continue with the wildcopy. */ + if (sequence.matchLength > 8) { + assert(op < oMatchEnd); + ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength - 8, ZSTD_overlap_src_before_dst); + } + return sequenceLength; +} + +HINT_INLINE +size_t ZSTD_execSequenceSplitLitBuffer(BYTE* op, + BYTE* const oend, const BYTE* const oend_w, 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) */ + const BYTE* const iLitEnd = *litPtr + sequence.litLength; + const BYTE* match = oLitEnd - sequence.offset; + + assert(op != NULL /* Precondition */); + assert(oend_w < oend /* No underflow */); + /* Handle edge cases in a slow path: + * - Read beyond end of literals + * - Match end is within WILDCOPY_OVERLIMIT of oend + * - 32-bit mode and the match length overflows + */ + if (UNLIKELY( + iLitEnd > litLimit || + oMatchEnd > oend_w || + (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH))) + return ZSTD_execSequenceEndSplitLitBuffer(op, oend, oend_w, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd); + + /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */ + assert(op <= oLitEnd /* No overflow */); + assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */); + assert(oMatchEnd <= oend /* No underflow */); + assert(iLitEnd <= litLimit /* Literal length is in bounds */); + assert(oLitEnd <= oend_w /* Can wildcopy literals */); + assert(oMatchEnd <= oend_w /* Can wildcopy matches */); + + /* Copy Literals: + * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9. + * We likely don't need the full 32-byte wildcopy. + */ + assert(WILDCOPY_OVERLENGTH >= 16); + ZSTD_copy16(op, (*litPtr)); + if (UNLIKELY(sequence.litLength > 16)) { + ZSTD_wildcopy(op+16, (*litPtr)+16, sequence.litLength-16, ZSTD_no_overlap); + } + op = oLitEnd; + *litPtr = iLitEnd; /* update for next sequence */ + + /* Copy Match */ + if (sequence.offset > (size_t)(oLitEnd - prefixStart)) { + /* offset beyond prefix -> go into extDict */ + RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, ""); + match = dictEnd + (match - prefixStart); + if (match + sequence.matchLength <= dictEnd) { + ZSTD_memmove(oLitEnd, match, sequence.matchLength); + return sequenceLength; + } + /* span extDict & currentPrefixSegment */ + { size_t const length1 = dictEnd - match; + ZSTD_memmove(oLitEnd, match, length1); + op = oLitEnd + length1; + sequence.matchLength -= length1; + match = prefixStart; + } } + /* Match within prefix of 1 or more bytes */ + assert(op <= oMatchEnd); + assert(oMatchEnd <= oend_w); + assert(match >= prefixStart); + assert(sequence.matchLength >= 1); + + /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy + * without overlap checking. + */ + if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) { + /* We bet on a full wildcopy for matches, since we expect matches to be + * longer than literals (in general). In silesia, ~10% of matches are longer + * than 16 bytes. + */ + ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap); + return sequenceLength; + } + assert(sequence.offset < WILDCOPY_VECLEN); + + /* Copy 8 bytes and spread the offset to be >= 8. */ + ZSTD_overlapCopy8(&op, &match, sequence.offset); + + /* If the match length is > 8 bytes, then continue with the wildcopy. */ + if (sequence.matchLength > 8) { + assert(op < oMatchEnd); + ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst); + } + 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_updateFseStateWithDInfo(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, U16 nextState, U32 nbBits) +{ + size_t const lowBits = BIT_readBits(bitD, nbBits); + DStatePtr->state = 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 offsets. + */ +#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; + +FORCE_INLINE_TEMPLATE seq_t +ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets) +{ + seq_t seq; + const ZSTD_seqSymbol* const llDInfo = seqState->stateLL.table + seqState->stateLL.state; + const ZSTD_seqSymbol* const mlDInfo = seqState->stateML.table + seqState->stateML.state; + const ZSTD_seqSymbol* const ofDInfo = seqState->stateOffb.table + seqState->stateOffb.state; + seq.matchLength = mlDInfo->baseValue; + seq.litLength = llDInfo->baseValue; + { U32 const ofBase = ofDInfo->baseValue; + BYTE const llBits = llDInfo->nbAdditionalBits; + BYTE const mlBits = mlDInfo->nbAdditionalBits; + BYTE const ofBits = ofDInfo->nbAdditionalBits; + BYTE const totalBits = llBits+mlBits+ofBits; + + U16 const llNext = llDInfo->nextState; + U16 const mlNext = mlDInfo->nextState; + U16 const ofNext = ofDInfo->nextState; + U32 const llnbBits = llDInfo->nbBits; + U32 const mlnbBits = mlDInfo->nbBits; + U32 const ofnbBits = ofDInfo->nbBits; + /* + * As gcc has better branch and block analyzers, sometimes it is only + * valuable to mark likelyness for clang, it gives around 3-4% of + * performance. + */ + + /* sequence */ + { size_t offset; + #if defined(__clang__) + if (LIKELY(ofBits > 1)) { + #else + if (ofBits > 1) { + #endif + 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); + } + seqState->prevOffset[2] = seqState->prevOffset[1]; + seqState->prevOffset[1] = seqState->prevOffset[0]; + seqState->prevOffset[0] = offset; + } else { + U32 const ll0 = (llDInfo->baseValue == 0); + if (LIKELY((ofBits == 0))) { + offset = seqState->prevOffset[ll0]; + seqState->prevOffset[1] = seqState->prevOffset[!ll0]; + seqState->prevOffset[0] = offset; + } else { + offset = ofBase + ll0 + BIT_readBitsFast(&seqState->DStream, 1); + { 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; + } } } + seq.offset = offset; + } + + #if defined(__clang__) + if (UNLIKELY(mlBits > 0)) + #else + if (mlBits > 0) + #endif + seq.matchLength += BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/); + + if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32)) + BIT_reloadDStream(&seqState->DStream); + if (MEM_64bits() && UNLIKELY(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); + + #if defined(__clang__) + if (UNLIKELY(llBits > 0)) + #else + if (llBits > 0) + #endif + seq.litLength += BIT_readBitsFast(&seqState->DStream, llBits/*>0*/); + + 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); + + ZSTD_updateFseStateWithDInfo(&seqState->stateLL, &seqState->DStream, llNext, llnbBits); /* <= 9 bits */ + ZSTD_updateFseStateWithDInfo(&seqState->stateML, &seqState->DStream, mlNext, mlnbBits); /* <= 9 bits */ + if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ + ZSTD_updateFseStateWithDInfo(&seqState->stateOffb, &seqState->DStream, ofNext, ofnbBits); /* <= 8 bits */ + } + + return seq; +} + +#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION +MEM_STATIC int ZSTD_dictionaryIsActive(ZSTD_DCtx const* dctx, BYTE const* prefixStart, BYTE const* oLitEnd) +{ + size_t const windowSize = dctx->fParams.windowSize; + /* No dictionary used. */ + if (dctx->dictContentEndForFuzzing == NULL) return 0; + /* Dictionary is our prefix. */ + if (prefixStart == dctx->dictContentBeginForFuzzing) return 1; + /* Dictionary is not our ext-dict. */ + if (dctx->dictEnd != dctx->dictContentEndForFuzzing) return 0; + /* Dictionary is not within our window size. */ + if ((size_t)(oLitEnd - prefixStart) >= windowSize) return 0; + /* Dictionary is active. */ + return 1; +} + +MEM_STATIC void ZSTD_assertValidSequence( + ZSTD_DCtx const* dctx, + BYTE const* op, BYTE const* oend, + seq_t const seq, + BYTE const* prefixStart, BYTE const* virtualStart) +{ +#if DEBUGLEVEL >= 1 + size_t const windowSize = dctx->fParams.windowSize; + size_t const sequenceSize = seq.litLength + seq.matchLength; + BYTE const* const oLitEnd = op + seq.litLength; + DEBUGLOG(6, "Checking sequence: litL=%u matchL=%u offset=%u", + (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset); + assert(op <= oend); + assert((size_t)(oend - op) >= sequenceSize); + assert(sequenceSize <= ZSTD_BLOCKSIZE_MAX); + if (ZSTD_dictionaryIsActive(dctx, prefixStart, oLitEnd)) { + size_t const dictSize = (size_t)((char const*)dctx->dictContentEndForFuzzing - (char const*)dctx->dictContentBeginForFuzzing); + /* Offset must be within the dictionary. */ + assert(seq.offset <= (size_t)(oLitEnd - virtualStart)); + assert(seq.offset <= windowSize + dictSize); + } else { + /* Offset must be within our window. */ + assert(seq.offset <= windowSize); + } +#else + (void)dctx, (void)op, (void)oend, (void)seq, (void)prefixStart, (void)virtualStart; +#endif +} +#endif + +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG + + +FORCE_INLINE_TEMPLATE size_t +DONT_VECTORIZE +ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + const BYTE* ip = (const BYTE*)seqStart; + const BYTE* const iend = ip + seqSize; + BYTE* const ostart = (BYTE*)dst; + BYTE* const oend = ostart + maxDstSize; + BYTE* op = ostart; + const BYTE* litPtr = dctx->litPtr; + const BYTE* litBufferEnd = dctx->litBufferEnd; + 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_bodySplitLitBuffer"); + (void)frame; + + /* 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]; } + RETURN_ERROR_IF( + ERR_isError(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); + assert(dst != NULL); + + ZSTD_STATIC_ASSERT( + BIT_DStream_unfinished < BIT_DStream_completed && + BIT_DStream_endOfBuffer < BIT_DStream_completed && + BIT_DStream_completed < BIT_DStream_overflow); + + /* decompress without overrunning litPtr begins */ + { + seq_t sequence = ZSTD_decodeSequence(&seqState, isLongOffset); + /* Align the decompression loop to 32 + 16 bytes. + * + * zstd compiled with gcc-9 on an Intel i9-9900k shows 10% decompression + * speed swings based on the alignment of the decompression loop. This + * performance swing is caused by parts of the decompression loop falling + * out of the DSB. The entire decompression loop should fit in the DSB, + * when it can't we get much worse performance. You can measure if you've + * hit the good case or the bad case with this perf command for some + * compressed file test.zst: + * + * perf stat -e cycles -e instructions -e idq.all_dsb_cycles_any_uops \ + * -e idq.all_mite_cycles_any_uops -- ./zstd -tq test.zst + * + * If you see most cycles served out of the MITE you've hit the bad case. + * If you see most cycles served out of the DSB you've hit the good case. + * If it is pretty even then you may be in an okay case. + * + * This issue has been reproduced on the following CPUs: + * - Kabylake: Macbook Pro (15-inch, 2019) 2.4 GHz Intel Core i9 + * Use Instruments->Counters to get DSB/MITE cycles. + * I never got performance swings, but I was able to + * go from the good case of mostly DSB to half of the + * cycles served from MITE. + * - Coffeelake: Intel i9-9900k + * - Coffeelake: Intel i7-9700k + * + * I haven't been able to reproduce the instability or DSB misses on any + * of the following CPUS: + * - Haswell + * - Broadwell: Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GH + * - Skylake + * + * Alignment is done for each of the three major decompression loops: + * - ZSTD_decompressSequences_bodySplitLitBuffer - presplit section of the literal buffer + * - ZSTD_decompressSequences_bodySplitLitBuffer - postsplit section of the literal buffer + * - ZSTD_decompressSequences_body + * Alignment choices are made to minimize large swings on bad cases and influence on performance + * from changes external to this code, rather than to overoptimize on the current commit. + * + * If you are seeing performance stability this script can help test. + * It tests on 4 commits in zstd where I saw performance change. + * + * https://gist.github.com/terrelln/9889fc06a423fd5ca6e99351564473f4 + */ +#if defined(__x86_64__) + __asm__(".p2align 6"); +# if __GNUC__ >= 7 + /* good for gcc-7, gcc-9, and gcc-11 */ + __asm__("nop"); + __asm__(".p2align 5"); + __asm__("nop"); + __asm__(".p2align 4"); +# if __GNUC__ == 8 || __GNUC__ == 10 + /* good for gcc-8 and gcc-10 */ + __asm__("nop"); + __asm__(".p2align 3"); +# endif +# endif +#endif + + /* Handle the initial state where litBuffer is currently split between dst and litExtraBuffer */ + for (; litPtr + sequence.litLength <= dctx->litBufferEnd; ) { + size_t const oneSeqSize = ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequence.litLength - WILDCOPY_OVERLENGTH, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd); +#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) + assert(!ZSTD_isError(oneSeqSize)); + if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase); +#endif + if (UNLIKELY(ZSTD_isError(oneSeqSize))) + return oneSeqSize; + DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize); + op += oneSeqSize; + if (UNLIKELY(!--nbSeq)) + break; + BIT_reloadDStream(&(seqState.DStream)); + sequence = ZSTD_decodeSequence(&seqState, isLongOffset); + } + + /* If there are more sequences, they will need to read literals from litExtraBuffer; copy over the remainder from dst and update litPtr and litEnd */ + if (nbSeq > 0) { + const size_t leftoverLit = dctx->litBufferEnd - litPtr; + if (leftoverLit) + { + RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer"); + ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit); + sequence.litLength -= leftoverLit; + op += leftoverLit; + } + litPtr = dctx->litExtraBuffer; + litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE; + dctx->litBufferLocation = ZSTD_not_in_dst; + { + size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd); +#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) + assert(!ZSTD_isError(oneSeqSize)); + if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase); +#endif + if (UNLIKELY(ZSTD_isError(oneSeqSize))) + return oneSeqSize; + DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize); + op += oneSeqSize; + if (--nbSeq) + BIT_reloadDStream(&(seqState.DStream)); + } + } + } + + if (nbSeq > 0) /* there is remaining lit from extra buffer */ + { + +#if defined(__x86_64__) + __asm__(".p2align 6"); + __asm__("nop"); +# if __GNUC__ != 7 + /* worse for gcc-7 better for gcc-8, gcc-9, and gcc-10 and clang */ + __asm__(".p2align 4"); + __asm__("nop"); + __asm__(".p2align 3"); +# elif __GNUC__ >= 11 + __asm__(".p2align 3"); +# else + __asm__(".p2align 5"); + __asm__("nop"); + __asm__(".p2align 3"); +# endif +#endif + + for (; ; ) { + seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset); + size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd); +#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) + assert(!ZSTD_isError(oneSeqSize)); + if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase); +#endif + if (UNLIKELY(ZSTD_isError(oneSeqSize))) + return oneSeqSize; + DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize); + op += oneSeqSize; + if (UNLIKELY(!--nbSeq)) + break; + BIT_reloadDStream(&(seqState.DStream)); + } + } + + /* check if reached exact end */ + DEBUGLOG(5, "ZSTD_decompressSequences_bodySplitLitBuffer: after decode loop, remaining nbSeq : %i", nbSeq); + RETURN_ERROR_IF(nbSeq, corruption_detected, ""); + RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, 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 */ + if (dctx->litBufferLocation == ZSTD_split) /* split hasn't been reached yet, first get dst then copy litExtraBuffer */ + { + size_t const lastLLSize = litBufferEnd - litPtr; + RETURN_ERROR_IF(lastLLSize > (size_t)(oend - op), dstSize_tooSmall, ""); + if (op != NULL) { + ZSTD_memmove(op, litPtr, lastLLSize); + op += lastLLSize; + } + litPtr = dctx->litExtraBuffer; + litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE; + dctx->litBufferLocation = ZSTD_not_in_dst; + } + { size_t const lastLLSize = litBufferEnd - litPtr; + RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, ""); + if (op != NULL) { + ZSTD_memcpy(op, litPtr, lastLLSize); + op += lastLLSize; + } + } + + return op-ostart; +} + +FORCE_INLINE_TEMPLATE size_t +DONT_VECTORIZE +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 int frame) +{ + const BYTE* ip = (const BYTE*)seqStart; + const BYTE* const iend = ip + seqSize; + BYTE* const ostart = (BYTE*)dst; + BYTE* const oend = dctx->litBufferLocation == ZSTD_not_in_dst ? ostart + maxDstSize : dctx->litBuffer; + 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"); + (void)frame; + + /* 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]; } + RETURN_ERROR_IF( + ERR_isError(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); + assert(dst != NULL); + + ZSTD_STATIC_ASSERT( + BIT_DStream_unfinished < BIT_DStream_completed && + BIT_DStream_endOfBuffer < BIT_DStream_completed && + BIT_DStream_completed < BIT_DStream_overflow); + +#if defined(__x86_64__) + __asm__(".p2align 6"); + __asm__("nop"); +# if __GNUC__ >= 7 + __asm__(".p2align 5"); + __asm__("nop"); + __asm__(".p2align 3"); +# else + __asm__(".p2align 4"); + __asm__("nop"); + __asm__(".p2align 3"); +# endif +#endif + + for ( ; ; ) { + seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset); + size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd); +#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) + assert(!ZSTD_isError(oneSeqSize)); + if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase); +#endif + if (UNLIKELY(ZSTD_isError(oneSeqSize))) + return oneSeqSize; + DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize); + op += oneSeqSize; + if (UNLIKELY(!--nbSeq)) + break; + BIT_reloadDStream(&(seqState.DStream)); + } + + /* check if reached exact end */ + DEBUGLOG(5, "ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i", nbSeq); + RETURN_ERROR_IF(nbSeq, corruption_detected, ""); + RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, 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; + RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, ""); + if (op != NULL) { + ZSTD_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, + const int frame) +{ + return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} + +static size_t +ZSTD_decompressSequencesSplitLitBuffer_default(ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + return ZSTD_decompressSequences_bodySplitLitBuffer(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} +#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ + +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT + +FORCE_INLINE_TEMPLATE size_t +ZSTD_prefetchMatch(size_t prefetchPos, seq_t const sequence, + const BYTE* const prefixStart, const BYTE* const dictEnd) +{ + prefetchPos += sequence.litLength; + { const BYTE* const matchBase = (sequence.offset > prefetchPos) ? dictEnd : prefixStart; + const BYTE* const match = matchBase + prefetchPos - sequence.offset; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted. + * No consequence though : memory address is only used for prefetching, not for dereferencing */ + PREFETCH_L1(match); PREFETCH_L1(match+CACHELINE_SIZE); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */ + } + return prefetchPos + sequence.matchLength; +} + +/* This decoding function employs prefetching + * to reduce latency impact of cache misses. + * It's generally employed when block contains a significant portion of long-distance matches + * or when coupled with a "cold" dictionary */ +FORCE_INLINE_TEMPLATE size_t +ZSTD_decompressSequencesLong_body( + ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + const BYTE* ip = (const BYTE*)seqStart; + const BYTE* const iend = ip + seqSize; + BYTE* const ostart = (BYTE*)dst; + BYTE* const oend = dctx->litBufferLocation == ZSTD_in_dst ? dctx->litBuffer : ostart + maxDstSize; + BYTE* op = ostart; + const BYTE* litPtr = dctx->litPtr; + const BYTE* litBufferEnd = dctx->litBufferEnd; + const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart); + const BYTE* const dictStart = (const BYTE*) (dctx->virtualStart); + const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd); + (void)frame; + + /* Regen sequences */ + if (nbSeq) { +#define STORED_SEQS 8 +#define STORED_SEQS_MASK (STORED_SEQS-1) +#define ADVANCED_SEQS STORED_SEQS + seq_t sequences[STORED_SEQS]; + int const seqAdvance = MIN(nbSeq, ADVANCED_SEQS); + seqState_t seqState; + int seqNb; + size_t prefetchPos = (size_t)(op-prefixStart); /* track position relative to prefixStart */ + + dctx->fseEntropy = 1; + { int i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; } + assert(dst != NULL); + assert(iend >= ip); + RETURN_ERROR_IF( + ERR_isError(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); + + /* prepare in advance */ + for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && (seqNb<seqAdvance); seqNb++) { + seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset); + prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd); + sequences[seqNb] = sequence; + } + RETURN_ERROR_IF(seqNb<seqAdvance, corruption_detected, ""); + + /* decompress without stomping litBuffer */ + for (; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb < nbSeq); seqNb++) { + seq_t sequence = ZSTD_decodeSequence(&seqState, isLongOffset); + size_t oneSeqSize; + + if (dctx->litBufferLocation == ZSTD_split && litPtr + sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength > dctx->litBufferEnd) + { + /* lit buffer is reaching split point, empty out the first buffer and transition to litExtraBuffer */ + const size_t leftoverLit = dctx->litBufferEnd - litPtr; + if (leftoverLit) + { + RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer"); + ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit); + sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength -= leftoverLit; + op += leftoverLit; + } + litPtr = dctx->litExtraBuffer; + litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE; + dctx->litBufferLocation = ZSTD_not_in_dst; + oneSeqSize = ZSTD_execSequence(op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd); +#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) + assert(!ZSTD_isError(oneSeqSize)); + if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart); +#endif + if (ZSTD_isError(oneSeqSize)) return oneSeqSize; + + prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd); + sequences[seqNb & STORED_SEQS_MASK] = sequence; + op += oneSeqSize; + } + else + { + /* lit buffer is either wholly contained in first or second split, or not split at all*/ + oneSeqSize = dctx->litBufferLocation == ZSTD_split ? + ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength - WILDCOPY_OVERLENGTH, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd) : + ZSTD_execSequence(op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd); +#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) + assert(!ZSTD_isError(oneSeqSize)); + if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart); +#endif + if (ZSTD_isError(oneSeqSize)) return oneSeqSize; + + prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd); + sequences[seqNb & STORED_SEQS_MASK] = sequence; + op += oneSeqSize; + } + } + RETURN_ERROR_IF(seqNb<nbSeq, corruption_detected, ""); + + /* finish queue */ + seqNb -= seqAdvance; + for ( ; seqNb<nbSeq ; seqNb++) { + seq_t *sequence = &(sequences[seqNb&STORED_SEQS_MASK]); + if (dctx->litBufferLocation == ZSTD_split && litPtr + sequence->litLength > dctx->litBufferEnd) + { + const size_t leftoverLit = dctx->litBufferEnd - litPtr; + if (leftoverLit) + { + RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer"); + ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit); + sequence->litLength -= leftoverLit; + op += leftoverLit; + } + litPtr = dctx->litExtraBuffer; + litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE; + dctx->litBufferLocation = ZSTD_not_in_dst; + { + size_t const oneSeqSize = ZSTD_execSequence(op, oend, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd); +#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) + assert(!ZSTD_isError(oneSeqSize)); + if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart); +#endif + if (ZSTD_isError(oneSeqSize)) return oneSeqSize; + op += oneSeqSize; + } + } + else + { + size_t const oneSeqSize = dctx->litBufferLocation == ZSTD_split ? + ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequence->litLength - WILDCOPY_OVERLENGTH, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd) : + ZSTD_execSequence(op, oend, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd); +#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) + assert(!ZSTD_isError(oneSeqSize)); + if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart); +#endif + if (ZSTD_isError(oneSeqSize)) return oneSeqSize; + op += oneSeqSize; + } + } + + /* 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 */ + if (dctx->litBufferLocation == ZSTD_split) /* first deplete literal buffer in dst, then copy litExtraBuffer */ + { + size_t const lastLLSize = litBufferEnd - litPtr; + RETURN_ERROR_IF(lastLLSize > (size_t)(oend - op), dstSize_tooSmall, ""); + if (op != NULL) { + ZSTD_memmove(op, litPtr, lastLLSize); + op += lastLLSize; + } + litPtr = dctx->litExtraBuffer; + litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE; + } + { size_t const lastLLSize = litBufferEnd - litPtr; + RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, ""); + if (op != NULL) { + ZSTD_memmove(op, litPtr, lastLLSize); + op += lastLLSize; + } + } + + return op-ostart; +} + +static size_t +ZSTD_decompressSequencesLong_default(ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} +#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ + + + +#if DYNAMIC_BMI2 + +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG +static BMI2_TARGET_ATTRIBUTE size_t +DONT_VECTORIZE +ZSTD_decompressSequences_bmi2(ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} +static BMI2_TARGET_ATTRIBUTE size_t +DONT_VECTORIZE +ZSTD_decompressSequencesSplitLitBuffer_bmi2(ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + return ZSTD_decompressSequences_bodySplitLitBuffer(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} +#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ + +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT +static BMI2_TARGET_ATTRIBUTE size_t +ZSTD_decompressSequencesLong_bmi2(ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} +#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ + +#endif /* DYNAMIC_BMI2 */ + +typedef size_t (*ZSTD_decompressSequences_t)( + ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame); + +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG +static size_t +ZSTD_decompressSequences(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + DEBUGLOG(5, "ZSTD_decompressSequences"); +#if DYNAMIC_BMI2 + if (ZSTD_DCtx_get_bmi2(dctx)) { + return ZSTD_decompressSequences_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); + } +#endif + return ZSTD_decompressSequences_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} +static size_t +ZSTD_decompressSequencesSplitLitBuffer(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + DEBUGLOG(5, "ZSTD_decompressSequencesSplitLitBuffer"); +#if DYNAMIC_BMI2 + if (ZSTD_DCtx_get_bmi2(dctx)) { + return ZSTD_decompressSequencesSplitLitBuffer_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); + } +#endif + return ZSTD_decompressSequencesSplitLitBuffer_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} +#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ + + +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT +/* ZSTD_decompressSequencesLong() : + * decompression function triggered when a minimum share of offsets is considered "long", + * aka out of cache. + * note : "long" definition seems overloaded here, sometimes meaning "wider than bitstream register", and sometimes meaning "farther than memory cache distance". + * This function will try to mitigate main memory latency through the use of prefetching */ +static size_t +ZSTD_decompressSequencesLong(ZSTD_DCtx* dctx, + void* dst, size_t maxDstSize, + const void* seqStart, size_t seqSize, int nbSeq, + const ZSTD_longOffset_e isLongOffset, + const int frame) +{ + DEBUGLOG(5, "ZSTD_decompressSequencesLong"); +#if DYNAMIC_BMI2 + if (ZSTD_DCtx_get_bmi2(dctx)) { + return ZSTD_decompressSequencesLong_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); + } +#endif + return ZSTD_decompressSequencesLong_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); +} +#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ + + + +#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ + !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) +/* ZSTD_getLongOffsetsShare() : + * condition : offTable must be valid + * @return : "share" of long offsets (arbitrarily defined as > (1<<23)) + * compared to maximum possible of (1<<OffFSELog) */ +static unsigned +ZSTD_getLongOffsetsShare(const ZSTD_seqSymbol* offTable) +{ + const void* ptr = offTable; + U32 const tableLog = ((const ZSTD_seqSymbol_header*)ptr)[0].tableLog; + const ZSTD_seqSymbol* table = offTable + 1; + U32 const max = 1 << tableLog; + U32 u, total = 0; + DEBUGLOG(5, "ZSTD_getLongOffsetsShare: (tableLog=%u)", tableLog); + + assert(max <= (1 << OffFSELog)); /* max not too large */ + for (u=0; u<max; u++) { + if (table[u].nbAdditionalBits > 22) total += 1; + } + + assert(tableLog <= OffFSELog); + total <<= (OffFSELog - tableLog); /* scale to OffFSELog */ + + return total; +} +#endif + +size_t +ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx, + void* dst, size_t dstCapacity, + const void* src, size_t srcSize, const int frame, const streaming_operation streaming) +{ /* blockType == blockCompressed */ + const BYTE* ip = (const BYTE*)src; + /* isLongOffset must be true if there are long offsets. + * Offsets are long if they are larger than 2^STREAM_ACCUMULATOR_MIN. + * We don't expect that to be the case in 64-bit mode. + * In block mode, window size is not known, so we have to be conservative. + * (note: but it could be evaluated from current-lowLimit) + */ + ZSTD_longOffset_e const isLongOffset = (ZSTD_longOffset_e)(MEM_32bits() && (!frame || (dctx->fParams.windowSize > (1ULL << STREAM_ACCUMULATOR_MIN)))); + DEBUGLOG(5, "ZSTD_decompressBlock_internal (size : %u)", (U32)srcSize); + + RETURN_ERROR_IF(srcSize >= ZSTD_BLOCKSIZE_MAX, srcSize_wrong, ""); + + /* Decode literals section */ + { size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize, dst, dstCapacity, streaming); + DEBUGLOG(5, "ZSTD_decodeLiteralsBlock : %u", (U32)litCSize); + if (ZSTD_isError(litCSize)) return litCSize; + ip += litCSize; + srcSize -= litCSize; + } + + /* Build Decoding Tables */ + { + /* These macros control at build-time which decompressor implementation + * we use. If neither is defined, we do some inspection and dispatch at + * runtime. + */ +#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ + !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) + int usePrefetchDecoder = dctx->ddictIsCold; +#endif + int nbSeq; + size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize); + if (ZSTD_isError(seqHSize)) return seqHSize; + ip += seqHSize; + srcSize -= seqHSize; + + RETURN_ERROR_IF(dst == NULL && nbSeq > 0, dstSize_tooSmall, "NULL not handled"); + +#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ + !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) + if ( !usePrefetchDecoder + && (!frame || (dctx->fParams.windowSize > (1<<24))) + && (nbSeq>ADVANCED_SEQS) ) { /* could probably use a larger nbSeq limit */ + U32 const shareLongOffsets = ZSTD_getLongOffsetsShare(dctx->OFTptr); + U32 const minShare = MEM_64bits() ? 7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */ + usePrefetchDecoder = (shareLongOffsets >= minShare); + } +#endif + + dctx->ddictIsCold = 0; + +#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ + !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) + if (usePrefetchDecoder) +#endif +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT + return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame); +#endif + +#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG + /* else */ + if (dctx->litBufferLocation == ZSTD_split) + return ZSTD_decompressSequencesSplitLitBuffer(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame); + else + return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame); +#endif + } +} + + +void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst, size_t dstSize) +{ + if (dst != dctx->previousDstEnd && dstSize > 0) { /* not contiguous */ + dctx->dictEnd = dctx->previousDstEnd; + dctx->virtualStart = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->prefixStart)); + dctx->prefixStart = dst; + dctx->previousDstEnd = dst; + } +} + + +size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, + void* dst, size_t dstCapacity, + const void* src, size_t srcSize) +{ + size_t dSize; + ZSTD_checkContinuity(dctx, dst, dstCapacity); + dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize, /* frame */ 0, not_streaming); + dctx->previousDstEnd = (char*)dst + dSize; + return dSize; +} |