/* * 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. */ /* This header contains definitions * that shall **only** be used by modules within lib/compress. */ #ifndef ZSTD_COMPRESS_H #define ZSTD_COMPRESS_H /*-************************************* * Dependencies ***************************************/ #include "zstd_internal.h" #include "zstd_cwksp.h" #ifdef ZSTD_MULTITHREAD # include "zstdmt_compress.h" #endif #if defined (__cplusplus) extern "C" { #endif /*-************************************* * Constants ***************************************/ #define kSearchStrength 8 #define HASH_READ_SIZE 8 #define ZSTD_DUBT_UNSORTED_MARK 1 /* For btlazy2 strategy, index ZSTD_DUBT_UNSORTED_MARK==1 means "unsorted". It could be confused for a real successor at index "1", if sorted as larger than its predecessor. It's not a big deal though : candidate will just be sorted again. Additionally, candidate position 1 will be lost. But candidate 1 cannot hide a large tree of candidates, so it's a minimal loss. The benefit is that ZSTD_DUBT_UNSORTED_MARK cannot be mishandled after table re-use with a different strategy. This constant is required by ZSTD_compressBlock_btlazy2() and ZSTD_reduceTable_internal() */ /*-************************************* * Context memory management ***************************************/ typedef enum { ZSTDcs_created=0, ZSTDcs_init, ZSTDcs_ongoing, ZSTDcs_ending } ZSTD_compressionStage_e; typedef enum { zcss_init=0, zcss_load, zcss_flush } ZSTD_cStreamStage; typedef struct ZSTD_prefixDict_s { const void* dict; size_t dictSize; ZSTD_dictContentType_e dictContentType; } ZSTD_prefixDict; typedef struct { void* dictBuffer; void const* dict; size_t dictSize; ZSTD_dictContentType_e dictContentType; ZSTD_CDict* cdict; } ZSTD_localDict; typedef struct { U32 CTable[HUF_CTABLE_SIZE_U32(255)]; HUF_repeat repeatMode; } ZSTD_hufCTables_t; typedef struct { FSE_CTable offcodeCTable[FSE_CTABLE_SIZE_U32(OffFSELog, MaxOff)]; FSE_CTable matchlengthCTable[FSE_CTABLE_SIZE_U32(MLFSELog, MaxML)]; FSE_CTable litlengthCTable[FSE_CTABLE_SIZE_U32(LLFSELog, MaxLL)]; FSE_repeat offcode_repeatMode; FSE_repeat matchlength_repeatMode; FSE_repeat litlength_repeatMode; } ZSTD_fseCTables_t; typedef struct { ZSTD_hufCTables_t huf; ZSTD_fseCTables_t fse; } ZSTD_entropyCTables_t; typedef struct { U32 off; U32 len; } ZSTD_match_t; typedef struct { int price; U32 off; U32 mlen; U32 litlen; U32 rep[ZSTD_REP_NUM]; } ZSTD_optimal_t; typedef enum { zop_dynamic=0, zop_predef } ZSTD_OptPrice_e; typedef struct { /* All tables are allocated inside cctx->workspace by ZSTD_resetCCtx_internal() */ unsigned* litFreq; /* table of literals statistics, of size 256 */ unsigned* litLengthFreq; /* table of litLength statistics, of size (MaxLL+1) */ unsigned* matchLengthFreq; /* table of matchLength statistics, of size (MaxML+1) */ unsigned* offCodeFreq; /* table of offCode statistics, of size (MaxOff+1) */ ZSTD_match_t* matchTable; /* list of found matches, of size ZSTD_OPT_NUM+1 */ ZSTD_optimal_t* priceTable; /* All positions tracked by optimal parser, of size ZSTD_OPT_NUM+1 */ U32 litSum; /* nb of literals */ U32 litLengthSum; /* nb of litLength codes */ U32 matchLengthSum; /* nb of matchLength codes */ U32 offCodeSum; /* nb of offset codes */ U32 litSumBasePrice; /* to compare to log2(litfreq) */ U32 litLengthSumBasePrice; /* to compare to log2(llfreq) */ U32 matchLengthSumBasePrice;/* to compare to log2(mlfreq) */ U32 offCodeSumBasePrice; /* to compare to log2(offreq) */ ZSTD_OptPrice_e priceType; /* prices can be determined dynamically, or follow a pre-defined cost structure */ const ZSTD_entropyCTables_t* symbolCosts; /* pre-calculated dictionary statistics */ ZSTD_literalCompressionMode_e literalCompressionMode; } optState_t; typedef struct { ZSTD_entropyCTables_t entropy; U32 rep[ZSTD_REP_NUM]; } ZSTD_compressedBlockState_t; typedef struct { BYTE const* nextSrc; /* next block here to continue on current prefix */ BYTE const* base; /* All regular indexes relative to this position */ BYTE const* dictBase; /* extDict indexes relative to this position */ U32 dictLimit; /* below that point, need extDict */ U32 lowLimit; /* below that point, no more valid data */ } ZSTD_window_t; typedef struct ZSTD_matchState_t ZSTD_matchState_t; struct ZSTD_matchState_t { ZSTD_window_t window; /* State for window round buffer management */ U32 loadedDictEnd; /* index of end of dictionary, within context's referential. * When loadedDictEnd != 0, a dictionary is in use, and still valid. * This relies on a mechanism to set loadedDictEnd=0 when dictionary is no longer within distance. * Such mechanism is provided within ZSTD_window_enforceMaxDist() and ZSTD_checkDictValidity(). * When dict referential is copied into active context (i.e. not attached), * loadedDictEnd == dictSize, since referential starts from zero. */ U32 nextToUpdate; /* index from which to continue table update */ U32 hashLog3; /* dispatch table for matches of len==3 : larger == faster, more memory */ U32* hashTable; U32* hashTable3; U32* chainTable; optState_t opt; /* optimal parser state */ const ZSTD_matchState_t* dictMatchState; ZSTD_compressionParameters cParams; }; typedef struct { ZSTD_compressedBlockState_t* prevCBlock; ZSTD_compressedBlockState_t* nextCBlock; ZSTD_matchState_t matchState; } ZSTD_blockState_t; typedef struct { U32 offset; U32 checksum; } ldmEntry_t; typedef struct { ZSTD_window_t window; /* State for the window round buffer management */ ldmEntry_t* hashTable; BYTE* bucketOffsets; /* Next position in bucket to insert entry */ U64 hashPower; /* Used to compute the rolling hash. * Depends on ldmParams.minMatchLength */ } ldmState_t; typedef struct { U32 enableLdm; /* 1 if enable long distance matching */ U32 hashLog; /* Log size of hashTable */ U32 bucketSizeLog; /* Log bucket size for collision resolution, at most 8 */ U32 minMatchLength; /* Minimum match length */ U32 hashRateLog; /* Log number of entries to skip */ U32 windowLog; /* Window log for the LDM */ } ldmParams_t; typedef struct { U32 offset; U32 litLength; U32 matchLength; } rawSeq; typedef struct { rawSeq* seq; /* The start of the sequences */ size_t pos; /* The position where reading stopped. <= size. */ size_t size; /* The number of sequences. <= capacity. */ size_t capacity; /* The capacity starting from `seq` pointer */ } rawSeqStore_t; typedef struct { int collectSequences; ZSTD_Sequence* seqStart; size_t seqIndex; size_t maxSequences; } SeqCollector; struct ZSTD_CCtx_params_s { ZSTD_format_e format; ZSTD_compressionParameters cParams; ZSTD_frameParameters fParams; int compressionLevel; int forceWindow; /* force back-references to respect limit of * 1< 63) ? ZSTD_highbit32(litLength) + LL_deltaCode : LL_Code[litLength]; } /* ZSTD_MLcode() : * note : mlBase = matchLength - MINMATCH; * because it's the format it's stored in seqStore->sequences */ MEM_STATIC U32 ZSTD_MLcode(U32 mlBase) { static const BYTE ML_Code[128] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 36, 36, 37, 37, 37, 37, 38, 38, 38, 38, 38, 38, 38, 38, 39, 39, 39, 39, 39, 39, 39, 39, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 40, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42 }; static const U32 ML_deltaCode = 36; return (mlBase > 127) ? ZSTD_highbit32(mlBase) + ML_deltaCode : ML_Code[mlBase]; } /* ZSTD_cParam_withinBounds: * @return 1 if value is within cParam bounds, * 0 otherwise */ MEM_STATIC int ZSTD_cParam_withinBounds(ZSTD_cParameter cParam, int value) { ZSTD_bounds const bounds = ZSTD_cParam_getBounds(cParam); if (ZSTD_isError(bounds.error)) return 0; if (value < bounds.lowerBound) return 0; if (value > bounds.upperBound) return 0; return 1; } /* ZSTD_noCompressBlock() : * Writes uncompressed block to dst buffer from given src. * Returns the size of the block */ MEM_STATIC size_t ZSTD_noCompressBlock (void* dst, size_t dstCapacity, const void* src, size_t srcSize, U32 lastBlock) { U32 const cBlockHeader24 = lastBlock + (((U32)bt_raw)<<1) + (U32)(srcSize << 3); RETURN_ERROR_IF(srcSize + ZSTD_blockHeaderSize > dstCapacity, dstSize_tooSmall); MEM_writeLE24(dst, cBlockHeader24); memcpy((BYTE*)dst + ZSTD_blockHeaderSize, src, srcSize); return ZSTD_blockHeaderSize + srcSize; } /* ZSTD_minGain() : * minimum compression required * to generate a compress block or a compressed literals section. * note : use same formula for both situations */ MEM_STATIC size_t ZSTD_minGain(size_t srcSize, ZSTD_strategy strat) { U32 const minlog = (strat>=ZSTD_btultra) ? (U32)(strat) - 1 : 6; ZSTD_STATIC_ASSERT(ZSTD_btultra == 8); assert(ZSTD_cParam_withinBounds(ZSTD_c_strategy, strat)); return (srcSize >> minlog) + 2; } /*! ZSTD_safecopyLiterals() : * memcpy() function that won't read beyond more than WILDCOPY_OVERLENGTH bytes past ilimit_w. * Only called when the sequence ends past ilimit_w, so it only needs to be optimized for single * large copies. */ static void ZSTD_safecopyLiterals(BYTE* op, BYTE const* ip, BYTE const* const iend, BYTE const* ilimit_w) { assert(iend > ilimit_w); if (ip <= ilimit_w) { ZSTD_wildcopy(op, ip, ilimit_w - ip, ZSTD_no_overlap); op += ilimit_w - ip; ip = ilimit_w; } while (ip < iend) *op++ = *ip++; } /*! ZSTD_storeSeq() : * Store a sequence (litlen, litPtr, offCode and mlBase) into seqStore_t. * `offCode` : distance to match + ZSTD_REP_MOVE (values <= ZSTD_REP_MOVE are repCodes). * `mlBase` : matchLength - MINMATCH * Allowed to overread literals up to litLimit. */ HINT_INLINE UNUSED_ATTR void ZSTD_storeSeq(seqStore_t* seqStorePtr, size_t litLength, const BYTE* literals, const BYTE* litLimit, U32 offCode, size_t mlBase) { BYTE const* const litLimit_w = litLimit - WILDCOPY_OVERLENGTH; BYTE const* const litEnd = literals + litLength; #if defined(DEBUGLEVEL) && (DEBUGLEVEL >= 6) static const BYTE* g_start = NULL; if (g_start==NULL) g_start = (const BYTE*)literals; /* note : index only works for compression within a single segment */ { U32 const pos = (U32)((const BYTE*)literals - g_start); DEBUGLOG(6, "Cpos%7u :%3u literals, match%4u bytes at offCode%7u", pos, (U32)litLength, (U32)mlBase+MINMATCH, (U32)offCode); } #endif assert((size_t)(seqStorePtr->sequences - seqStorePtr->sequencesStart) < seqStorePtr->maxNbSeq); /* copy Literals */ assert(seqStorePtr->maxNbLit <= 128 KB); assert(seqStorePtr->lit + litLength <= seqStorePtr->litStart + seqStorePtr->maxNbLit); assert(literals + litLength <= litLimit); if (litEnd <= litLimit_w) { /* Common case we can use wildcopy. * First copy 16 bytes, because literals are likely short. */ assert(WILDCOPY_OVERLENGTH >= 16); ZSTD_copy16(seqStorePtr->lit, literals); if (litLength > 16) { ZSTD_wildcopy(seqStorePtr->lit+16, literals+16, (ptrdiff_t)litLength-16, ZSTD_no_overlap); } } else { ZSTD_safecopyLiterals(seqStorePtr->lit, literals, litEnd, litLimit_w); } seqStorePtr->lit += litLength; /* literal Length */ if (litLength>0xFFFF) { assert(seqStorePtr->longLengthID == 0); /* there can only be a single long length */ seqStorePtr->longLengthID = 1; seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart); } seqStorePtr->sequences[0].litLength = (U16)litLength; /* match offset */ seqStorePtr->sequences[0].offset = offCode + 1; /* match Length */ if (mlBase>0xFFFF) { assert(seqStorePtr->longLengthID == 0); /* there can only be a single long length */ seqStorePtr->longLengthID = 2; seqStorePtr->longLengthPos = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart); } seqStorePtr->sequences[0].matchLength = (U16)mlBase; seqStorePtr->sequences++; } /*-************************************* * Match length counter ***************************************/ static unsigned ZSTD_NbCommonBytes (size_t val) { if (MEM_isLittleEndian()) { if (MEM_64bits()) { # if defined(_MSC_VER) && defined(_WIN64) unsigned long r = 0; _BitScanForward64( &r, (U64)val ); return (unsigned)(r>>3); # elif defined(__GNUC__) && (__GNUC__ >= 4) return (__builtin_ctzll((U64)val) >> 3); # else static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5, 3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5, 5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4, 4, 5, 7, 2, 6, 5, 7, 6, 7, 7 }; return DeBruijnBytePos[((U64)((val & -(long long)val) * 0x0218A392CDABBD3FULL)) >> 58]; # endif } else { /* 32 bits */ # if defined(_MSC_VER) unsigned long r=0; _BitScanForward( &r, (U32)val ); return (unsigned)(r>>3); # elif defined(__GNUC__) && (__GNUC__ >= 3) return (__builtin_ctz((U32)val) >> 3); # else static const int DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 }; return DeBruijnBytePos[((U32)((val & -(S32)val) * 0x077CB531U)) >> 27]; # endif } } else { /* Big Endian CPU */ if (MEM_64bits()) { # if defined(_MSC_VER) && defined(_WIN64) unsigned long r = 0; _BitScanReverse64( &r, val ); return (unsigned)(r>>3); # elif defined(__GNUC__) && (__GNUC__ >= 4) return (__builtin_clzll(val) >> 3); # else unsigned r; const unsigned n32 = sizeof(size_t)*4; /* calculate this way due to compiler complaining in 32-bits mode */ if (!(val>>n32)) { r=4; } else { r=0; val>>=n32; } if (!(val>>16)) { r+=2; val>>=8; } else { val>>=24; } r += (!val); return r; # endif } else { /* 32 bits */ # if defined(_MSC_VER) unsigned long r = 0; _BitScanReverse( &r, (unsigned long)val ); return (unsigned)(r>>3); # elif defined(__GNUC__) && (__GNUC__ >= 3) return (__builtin_clz((U32)val) >> 3); # else unsigned r; if (!(val>>16)) { r=2; val>>=8; } else { r=0; val>>=24; } r += (!val); return r; # endif } } } MEM_STATIC size_t ZSTD_count(const BYTE* pIn, const BYTE* pMatch, const BYTE* const pInLimit) { const BYTE* const pStart = pIn; const BYTE* const pInLoopLimit = pInLimit - (sizeof(size_t)-1); if (pIn < pInLoopLimit) { { size_t const diff = MEM_readST(pMatch) ^ MEM_readST(pIn); if (diff) return ZSTD_NbCommonBytes(diff); } pIn+=sizeof(size_t); pMatch+=sizeof(size_t); while (pIn < pInLoopLimit) { size_t const diff = MEM_readST(pMatch) ^ MEM_readST(pIn); if (!diff) { pIn+=sizeof(size_t); pMatch+=sizeof(size_t); continue; } pIn += ZSTD_NbCommonBytes(diff); return (size_t)(pIn - pStart); } } if (MEM_64bits() && (pIn<(pInLimit-3)) && (MEM_read32(pMatch) == MEM_read32(pIn))) { pIn+=4; pMatch+=4; } if ((pIn<(pInLimit-1)) && (MEM_read16(pMatch) == MEM_read16(pIn))) { pIn+=2; pMatch+=2; } if ((pIn> (32-h) ; } MEM_STATIC size_t ZSTD_hash3Ptr(const void* ptr, U32 h) { return ZSTD_hash3(MEM_readLE32(ptr), h); } /* only in zstd_opt.h */ static const U32 prime4bytes = 2654435761U; static U32 ZSTD_hash4(U32 u, U32 h) { return (u * prime4bytes) >> (32-h) ; } static size_t ZSTD_hash4Ptr(const void* ptr, U32 h) { return ZSTD_hash4(MEM_read32(ptr), h); } static const U64 prime5bytes = 889523592379ULL; static size_t ZSTD_hash5(U64 u, U32 h) { return (size_t)(((u << (64-40)) * prime5bytes) >> (64-h)) ; } static size_t ZSTD_hash5Ptr(const void* p, U32 h) { return ZSTD_hash5(MEM_readLE64(p), h); } static const U64 prime6bytes = 227718039650203ULL; static size_t ZSTD_hash6(U64 u, U32 h) { return (size_t)(((u << (64-48)) * prime6bytes) >> (64-h)) ; } static size_t ZSTD_hash6Ptr(const void* p, U32 h) { return ZSTD_hash6(MEM_readLE64(p), h); } static const U64 prime7bytes = 58295818150454627ULL; static size_t ZSTD_hash7(U64 u, U32 h) { return (size_t)(((u << (64-56)) * prime7bytes) >> (64-h)) ; } static size_t ZSTD_hash7Ptr(const void* p, U32 h) { return ZSTD_hash7(MEM_readLE64(p), h); } static const U64 prime8bytes = 0xCF1BBCDCB7A56463ULL; static size_t ZSTD_hash8(U64 u, U32 h) { return (size_t)(((u) * prime8bytes) >> (64-h)) ; } static size_t ZSTD_hash8Ptr(const void* p, U32 h) { return ZSTD_hash8(MEM_readLE64(p), h); } MEM_STATIC size_t ZSTD_hashPtr(const void* p, U32 hBits, U32 mls) { switch(mls) { default: case 4: return ZSTD_hash4Ptr(p, hBits); case 5: return ZSTD_hash5Ptr(p, hBits); case 6: return ZSTD_hash6Ptr(p, hBits); case 7: return ZSTD_hash7Ptr(p, hBits); case 8: return ZSTD_hash8Ptr(p, hBits); } } /** ZSTD_ipow() : * Return base^exponent. */ static U64 ZSTD_ipow(U64 base, U64 exponent) { U64 power = 1; while (exponent) { if (exponent & 1) power *= base; exponent >>= 1; base *= base; } return power; } #define ZSTD_ROLL_HASH_CHAR_OFFSET 10 /** ZSTD_rollingHash_append() : * Add the buffer to the hash value. */ static U64 ZSTD_rollingHash_append(U64 hash, void const* buf, size_t size) { BYTE const* istart = (BYTE const*)buf; size_t pos; for (pos = 0; pos < size; ++pos) { hash *= prime8bytes; hash += istart[pos] + ZSTD_ROLL_HASH_CHAR_OFFSET; } return hash; } /** ZSTD_rollingHash_compute() : * Compute the rolling hash value of the buffer. */ MEM_STATIC U64 ZSTD_rollingHash_compute(void const* buf, size_t size) { return ZSTD_rollingHash_append(0, buf, size); } /** ZSTD_rollingHash_primePower() : * Compute the primePower to be passed to ZSTD_rollingHash_rotate() for a hash * over a window of length bytes. */ MEM_STATIC U64 ZSTD_rollingHash_primePower(U32 length) { return ZSTD_ipow(prime8bytes, length - 1); } /** ZSTD_rollingHash_rotate() : * Rotate the rolling hash by one byte. */ MEM_STATIC U64 ZSTD_rollingHash_rotate(U64 hash, BYTE toRemove, BYTE toAdd, U64 primePower) { hash -= (toRemove + ZSTD_ROLL_HASH_CHAR_OFFSET) * primePower; hash *= prime8bytes; hash += toAdd + ZSTD_ROLL_HASH_CHAR_OFFSET; return hash; } /*-************************************* * Round buffer management ***************************************/ #if (ZSTD_WINDOWLOG_MAX_64 > 31) # error "ZSTD_WINDOWLOG_MAX is too large : would overflow ZSTD_CURRENT_MAX" #endif /* Max current allowed */ #define ZSTD_CURRENT_MAX ((3U << 29) + (1U << ZSTD_WINDOWLOG_MAX)) /* Maximum chunk size before overflow correction needs to be called again */ #define ZSTD_CHUNKSIZE_MAX \ ( ((U32)-1) /* Maximum ending current index */ \ - ZSTD_CURRENT_MAX) /* Maximum beginning lowLimit */ /** * ZSTD_window_clear(): * Clears the window containing the history by simply setting it to empty. */ MEM_STATIC void ZSTD_window_clear(ZSTD_window_t* window) { size_t const endT = (size_t)(window->nextSrc - window->base); U32 const end = (U32)endT; window->lowLimit = end; window->dictLimit = end; } /** * ZSTD_window_hasExtDict(): * Returns non-zero if the window has a non-empty extDict. */ MEM_STATIC U32 ZSTD_window_hasExtDict(ZSTD_window_t const window) { return window.lowLimit < window.dictLimit; } /** * ZSTD_matchState_dictMode(): * Inspects the provided matchState and figures out what dictMode should be * passed to the compressor. */ MEM_STATIC ZSTD_dictMode_e ZSTD_matchState_dictMode(const ZSTD_matchState_t *ms) { return ZSTD_window_hasExtDict(ms->window) ? ZSTD_extDict : ms->dictMatchState != NULL ? ZSTD_dictMatchState : ZSTD_noDict; } /** * ZSTD_window_needOverflowCorrection(): * Returns non-zero if the indices are getting too large and need overflow * protection. */ MEM_STATIC U32 ZSTD_window_needOverflowCorrection(ZSTD_window_t const window, void const* srcEnd) { U32 const current = (U32)((BYTE const*)srcEnd - window.base); return current > ZSTD_CURRENT_MAX; } /** * ZSTD_window_correctOverflow(): * Reduces the indices to protect from index overflow. * Returns the correction made to the indices, which must be applied to every * stored index. * * The least significant cycleLog bits of the indices must remain the same, * which may be 0. Every index up to maxDist in the past must be valid. * NOTE: (maxDist & cycleMask) must be zero. */ MEM_STATIC U32 ZSTD_window_correctOverflow(ZSTD_window_t* window, U32 cycleLog, U32 maxDist, void const* src) { /* preemptive overflow correction: * 1. correction is large enough: * lowLimit > (3<<29) ==> current > 3<<29 + 1< (3<<29 + 1< (3<<29) - (1< (3<<29) - (1<<30) (NOTE: chainLog <= 30) * > 1<<29 * * 2. (ip+ZSTD_CHUNKSIZE_MAX - cctx->base) doesn't overflow: * After correction, current is less than (1<base < 1<<32. * 3. (cctx->lowLimit + 1< 3<<29 + 1<base); U32 const newCurrent = (current & cycleMask) + maxDist; U32 const correction = current - newCurrent; assert((maxDist & cycleMask) == 0); assert(current > newCurrent); /* Loose bound, should be around 1<<29 (see above) */ assert(correction > 1<<28); window->base += correction; window->dictBase += correction; window->lowLimit -= correction; window->dictLimit -= correction; DEBUGLOG(4, "Correction of 0x%x bytes to lowLimit=0x%x", correction, window->lowLimit); return correction; } /** * ZSTD_window_enforceMaxDist(): * Updates lowLimit so that: * (srcEnd - base) - lowLimit == maxDist + loadedDictEnd * * It ensures index is valid as long as index >= lowLimit. * This must be called before a block compression call. * * loadedDictEnd is only defined if a dictionary is in use for current compression. * As the name implies, loadedDictEnd represents the index at end of dictionary. * The value lies within context's referential, it can be directly compared to blockEndIdx. * * If loadedDictEndPtr is NULL, no dictionary is in use, and we use loadedDictEnd == 0. * If loadedDictEndPtr is not NULL, we set it to zero after updating lowLimit. * This is because dictionaries are allowed to be referenced fully * as long as the last byte of the dictionary is in the window. * Once input has progressed beyond window size, dictionary cannot be referenced anymore. * * In normal dict mode, the dictionary lies between lowLimit and dictLimit. * In dictMatchState mode, lowLimit and dictLimit are the same, * and the dictionary is below them. * forceWindow and dictMatchState are therefore incompatible. */ MEM_STATIC void ZSTD_window_enforceMaxDist(ZSTD_window_t* window, const void* blockEnd, U32 maxDist, U32* loadedDictEndPtr, const ZSTD_matchState_t** dictMatchStatePtr) { U32 const blockEndIdx = (U32)((BYTE const*)blockEnd - window->base); U32 const loadedDictEnd = (loadedDictEndPtr != NULL) ? *loadedDictEndPtr : 0; DEBUGLOG(5, "ZSTD_window_enforceMaxDist: blockEndIdx=%u, maxDist=%u, loadedDictEnd=%u", (unsigned)blockEndIdx, (unsigned)maxDist, (unsigned)loadedDictEnd); /* - When there is no dictionary : loadedDictEnd == 0. In which case, the test (blockEndIdx > maxDist) is merely to avoid overflowing next operation `newLowLimit = blockEndIdx - maxDist`. - When there is a standard dictionary : Index referential is copied from the dictionary, which means it starts from 0. In which case, loadedDictEnd == dictSize, and it makes sense to compare `blockEndIdx > maxDist + dictSize` since `blockEndIdx` also starts from zero. - When there is an attached dictionary : loadedDictEnd is expressed within the referential of the context, so it can be directly compared against blockEndIdx. */ if (blockEndIdx > maxDist + loadedDictEnd) { U32 const newLowLimit = blockEndIdx - maxDist; if (window->lowLimit < newLowLimit) window->lowLimit = newLowLimit; if (window->dictLimit < window->lowLimit) { DEBUGLOG(5, "Update dictLimit to match lowLimit, from %u to %u", (unsigned)window->dictLimit, (unsigned)window->lowLimit); window->dictLimit = window->lowLimit; } /* On reaching window size, dictionaries are invalidated */ if (loadedDictEndPtr) *loadedDictEndPtr = 0; if (dictMatchStatePtr) *dictMatchStatePtr = NULL; } } /* Similar to ZSTD_window_enforceMaxDist(), * but only invalidates dictionary * when input progresses beyond window size. * assumption : loadedDictEndPtr and dictMatchStatePtr are valid (non NULL) * loadedDictEnd uses same referential as window->base * maxDist is the window size */ MEM_STATIC void ZSTD_checkDictValidity(const ZSTD_window_t* window, const void* blockEnd, U32 maxDist, U32* loadedDictEndPtr, const ZSTD_matchState_t** dictMatchStatePtr) { assert(loadedDictEndPtr != NULL); assert(dictMatchStatePtr != NULL); { U32 const blockEndIdx = (U32)((BYTE const*)blockEnd - window->base); U32 const loadedDictEnd = *loadedDictEndPtr; DEBUGLOG(5, "ZSTD_checkDictValidity: blockEndIdx=%u, maxDist=%u, loadedDictEnd=%u", (unsigned)blockEndIdx, (unsigned)maxDist, (unsigned)loadedDictEnd); assert(blockEndIdx >= loadedDictEnd); if (blockEndIdx > loadedDictEnd + maxDist) { /* On reaching window size, dictionaries are invalidated. * For simplification, if window size is reached anywhere within next block, * the dictionary is invalidated for the full block. */ DEBUGLOG(6, "invalidating dictionary for current block (distance > windowSize)"); *loadedDictEndPtr = 0; *dictMatchStatePtr = NULL; } else { if (*loadedDictEndPtr != 0) { DEBUGLOG(6, "dictionary considered valid for current block"); } } } } MEM_STATIC void ZSTD_window_init(ZSTD_window_t* window) { memset(window, 0, sizeof(*window)); window->base = (BYTE const*)""; window->dictBase = (BYTE const*)""; window->dictLimit = 1; /* start from 1, so that 1st position is valid */ window->lowLimit = 1; /* it ensures first and later CCtx usages compress the same */ window->nextSrc = window->base + 1; /* see issue #1241 */ } /** * ZSTD_window_update(): * Updates the window by appending [src, src + srcSize) to the window. * If it is not contiguous, the current prefix becomes the extDict, and we * forget about the extDict. Handles overlap of the prefix and extDict. * Returns non-zero if the segment is contiguous. */ MEM_STATIC U32 ZSTD_window_update(ZSTD_window_t* window, void const* src, size_t srcSize) { BYTE const* const ip = (BYTE const*)src; U32 contiguous = 1; DEBUGLOG(5, "ZSTD_window_update"); if (srcSize == 0) return contiguous; assert(window->base != NULL); assert(window->dictBase != NULL); /* Check if blocks follow each other */ if (src != window->nextSrc) { /* not contiguous */ size_t const distanceFromBase = (size_t)(window->nextSrc - window->base); DEBUGLOG(5, "Non contiguous blocks, new segment starts at %u", window->dictLimit); window->lowLimit = window->dictLimit; assert(distanceFromBase == (size_t)(U32)distanceFromBase); /* should never overflow */ window->dictLimit = (U32)distanceFromBase; window->dictBase = window->base; window->base = ip - distanceFromBase; // ms->nextToUpdate = window->dictLimit; if (window->dictLimit - window->lowLimit < HASH_READ_SIZE) window->lowLimit = window->dictLimit; /* too small extDict */ contiguous = 0; } window->nextSrc = ip + srcSize; /* if input and dictionary overlap : reduce dictionary (area presumed modified by input) */ if ( (ip+srcSize > window->dictBase + window->lowLimit) & (ip < window->dictBase + window->dictLimit)) { ptrdiff_t const highInputIdx = (ip + srcSize) - window->dictBase; U32 const lowLimitMax = (highInputIdx > (ptrdiff_t)window->dictLimit) ? window->dictLimit : (U32)highInputIdx; window->lowLimit = lowLimitMax; DEBUGLOG(5, "Overlapping extDict and input : new lowLimit = %u", window->lowLimit); } return contiguous; } MEM_STATIC U32 ZSTD_getLowestMatchIndex(const ZSTD_matchState_t* ms, U32 current, unsigned windowLog) { U32 const maxDistance = 1U << windowLog; U32 const lowestValid = ms->window.lowLimit; U32 const withinWindow = (current - lowestValid > maxDistance) ? current - maxDistance : lowestValid; U32 const isDictionary = (ms->loadedDictEnd != 0); U32 const matchLowest = isDictionary ? lowestValid : withinWindow; return matchLowest; } /* debug functions */ #if (DEBUGLEVEL>=2) MEM_STATIC double ZSTD_fWeight(U32 rawStat) { U32 const fp_accuracy = 8; U32 const fp_multiplier = (1 << fp_accuracy); U32 const newStat = rawStat + 1; U32 const hb = ZSTD_highbit32(newStat); U32 const BWeight = hb * fp_multiplier; U32 const FWeight = (newStat << fp_accuracy) >> hb; U32 const weight = BWeight + FWeight; assert(hb + fp_accuracy < 31); return (double)weight / fp_multiplier; } /* display a table content, * listing each element, its frequency, and its predicted bit cost */ MEM_STATIC void ZSTD_debugTable(const U32* table, U32 max) { unsigned u, sum; for (u=0, sum=0; u<=max; u++) sum += table[u]; DEBUGLOG(2, "total nb elts: %u", sum); for (u=0; u<=max; u++) { DEBUGLOG(2, "%2u: %5u (%.2f)", u, table[u], ZSTD_fWeight(sum) - ZSTD_fWeight(table[u]) ); } } #endif #if defined (__cplusplus) } #endif /* =============================================================== * Shared internal declarations * These prototypes may be called from sources not in lib/compress * =============================================================== */ /* ZSTD_loadCEntropy() : * dict : must point at beginning of a valid zstd dictionary. * return : size of dictionary header (size of magic number + dict ID + entropy tables) * assumptions : magic number supposed already checked * and dictSize >= 8 */ size_t ZSTD_loadCEntropy(ZSTD_compressedBlockState_t* bs, void* workspace, short* offcodeNCount, unsigned* offcodeMaxValue, const void* const dict, size_t dictSize); void ZSTD_reset_compressedBlockState(ZSTD_compressedBlockState_t* bs); /* ============================================================== * Private declarations * These prototypes shall only be called from within lib/compress * ============================================================== */ /* ZSTD_getCParamsFromCCtxParams() : * cParams are built depending on compressionLevel, src size hints, * LDM and manually set compression parameters. * Note: srcSizeHint == 0 means 0! */ ZSTD_compressionParameters ZSTD_getCParamsFromCCtxParams( const ZSTD_CCtx_params* CCtxParams, U64 srcSizeHint, size_t dictSize); /*! ZSTD_initCStream_internal() : * Private use only. Init streaming operation. * expects params to be valid. * must receive dict, or cdict, or none, but not both. * @return : 0, or an error code */ size_t ZSTD_initCStream_internal(ZSTD_CStream* zcs, const void* dict, size_t dictSize, const ZSTD_CDict* cdict, const ZSTD_CCtx_params* params, unsigned long long pledgedSrcSize); void ZSTD_resetSeqStore(seqStore_t* ssPtr); /*! ZSTD_getCParamsFromCDict() : * as the name implies */ ZSTD_compressionParameters ZSTD_getCParamsFromCDict(const ZSTD_CDict* cdict); /* ZSTD_compressBegin_advanced_internal() : * Private use only. To be called from zstdmt_compress.c. */ size_t ZSTD_compressBegin_advanced_internal(ZSTD_CCtx* cctx, const void* dict, size_t dictSize, ZSTD_dictContentType_e dictContentType, ZSTD_dictTableLoadMethod_e dtlm, const ZSTD_CDict* cdict, const ZSTD_CCtx_params* params, unsigned long long pledgedSrcSize); /* ZSTD_compress_advanced_internal() : * Private use only. To be called from zstdmt_compress.c. */ size_t ZSTD_compress_advanced_internal(ZSTD_CCtx* cctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, const void* dict,size_t dictSize, const ZSTD_CCtx_params* params); /* ZSTD_writeLastEmptyBlock() : * output an empty Block with end-of-frame mark to complete a frame * @return : size of data written into `dst` (== ZSTD_blockHeaderSize (defined in zstd_internal.h)) * or an error code if `dstCapacity` is too small (