/* * Copyright (c) Meta Platforms, Inc. and affiliates. * 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. */ #include "zstd_compress_internal.h" #include "hist.h" #include "zstd_opt.h" #define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats */ #define ZSTD_MAX_PRICE (1<<30) #define ZSTD_PREDEF_THRESHOLD 8 /* if srcSize < ZSTD_PREDEF_THRESHOLD, symbols' cost is assumed static, directly determined by pre-defined distributions */ /*-************************************* * Price functions for optimal parser ***************************************/ #if 0 /* approximation at bit level (for tests) */ # define BITCOST_ACCURACY 0 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) # define WEIGHT(stat, opt) ((void)(opt), ZSTD_bitWeight(stat)) #elif 0 /* fractional bit accuracy (for tests) */ # define BITCOST_ACCURACY 8 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) # define WEIGHT(stat,opt) ((void)(opt), ZSTD_fracWeight(stat)) #else /* opt==approx, ultra==accurate */ # define BITCOST_ACCURACY 8 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) # define WEIGHT(stat,opt) ((opt) ? ZSTD_fracWeight(stat) : ZSTD_bitWeight(stat)) #endif /* ZSTD_bitWeight() : * provide estimated "cost" of a stat in full bits only */ MEM_STATIC U32 ZSTD_bitWeight(U32 stat) { return (ZSTD_highbit32(stat+1) * BITCOST_MULTIPLIER); } /* ZSTD_fracWeight() : * provide fractional-bit "cost" of a stat, * using linear interpolation approximation */ MEM_STATIC U32 ZSTD_fracWeight(U32 rawStat) { U32 const stat = rawStat + 1; U32 const hb = ZSTD_highbit32(stat); U32 const BWeight = hb * BITCOST_MULTIPLIER; /* Fweight was meant for "Fractional weight" * but it's effectively a value between 1 and 2 * using fixed point arithmetic */ U32 const FWeight = (stat << BITCOST_ACCURACY) >> hb; U32 const weight = BWeight + FWeight; assert(hb + BITCOST_ACCURACY < 31); return weight; } #if (DEBUGLEVEL>=2) /* debugging function, * @return price in bytes as fractional value * for debug messages only */ MEM_STATIC double ZSTD_fCost(int price) { return (double)price / (BITCOST_MULTIPLIER*8); } #endif static int ZSTD_compressedLiterals(optState_t const* const optPtr) { return optPtr->literalCompressionMode != ZSTD_ps_disable; } static void ZSTD_setBasePrices(optState_t* optPtr, int optLevel) { if (ZSTD_compressedLiterals(optPtr)) optPtr->litSumBasePrice = WEIGHT(optPtr->litSum, optLevel); optPtr->litLengthSumBasePrice = WEIGHT(optPtr->litLengthSum, optLevel); optPtr->matchLengthSumBasePrice = WEIGHT(optPtr->matchLengthSum, optLevel); optPtr->offCodeSumBasePrice = WEIGHT(optPtr->offCodeSum, optLevel); } static U32 sum_u32(const unsigned table[], size_t nbElts) { size_t n; U32 total = 0; for (n=0; n0); unsigned const newStat = base + (table[s] >> shift); sum += newStat; table[s] = newStat; } return sum; } /* ZSTD_scaleStats() : * reduce all elt frequencies in table if sum too large * return the resulting sum of elements */ static U32 ZSTD_scaleStats(unsigned* table, U32 lastEltIndex, U32 logTarget) { U32 const prevsum = sum_u32(table, lastEltIndex+1); U32 const factor = prevsum >> logTarget; DEBUGLOG(5, "ZSTD_scaleStats (nbElts=%u, target=%u)", (unsigned)lastEltIndex+1, (unsigned)logTarget); assert(logTarget < 30); if (factor <= 1) return prevsum; return ZSTD_downscaleStats(table, lastEltIndex, ZSTD_highbit32(factor), base_1guaranteed); } /* ZSTD_rescaleFreqs() : * if first block (detected by optPtr->litLengthSum == 0) : init statistics * take hints from dictionary if there is one * and init from zero if there is none, * using src for literals stats, and baseline stats for sequence symbols * otherwise downscale existing stats, to be used as seed for next block. */ static void ZSTD_rescaleFreqs(optState_t* const optPtr, const BYTE* const src, size_t const srcSize, int const optLevel) { int const compressedLiterals = ZSTD_compressedLiterals(optPtr); DEBUGLOG(5, "ZSTD_rescaleFreqs (srcSize=%u)", (unsigned)srcSize); optPtr->priceType = zop_dynamic; if (optPtr->litLengthSum == 0) { /* no literals stats collected -> first block assumed -> init */ /* heuristic: use pre-defined stats for too small inputs */ if (srcSize <= ZSTD_PREDEF_THRESHOLD) { DEBUGLOG(5, "srcSize <= %i : use predefined stats", ZSTD_PREDEF_THRESHOLD); optPtr->priceType = zop_predef; } assert(optPtr->symbolCosts != NULL); if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid) { /* huffman stats covering the full value set : table presumed generated by dictionary */ optPtr->priceType = zop_dynamic; if (compressedLiterals) { /* generate literals statistics from huffman table */ unsigned lit; assert(optPtr->litFreq != NULL); optPtr->litSum = 0; for (lit=0; lit<=MaxLit; lit++) { U32 const scaleLog = 11; /* scale to 2K */ U32 const bitCost = HUF_getNbBitsFromCTable(optPtr->symbolCosts->huf.CTable, lit); assert(bitCost <= scaleLog); optPtr->litFreq[lit] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; optPtr->litSum += optPtr->litFreq[lit]; } } { unsigned ll; FSE_CState_t llstate; FSE_initCState(&llstate, optPtr->symbolCosts->fse.litlengthCTable); optPtr->litLengthSum = 0; for (ll=0; ll<=MaxLL; ll++) { U32 const scaleLog = 10; /* scale to 1K */ U32 const bitCost = FSE_getMaxNbBits(llstate.symbolTT, ll); assert(bitCost < scaleLog); optPtr->litLengthFreq[ll] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; optPtr->litLengthSum += optPtr->litLengthFreq[ll]; } } { unsigned ml; FSE_CState_t mlstate; FSE_initCState(&mlstate, optPtr->symbolCosts->fse.matchlengthCTable); optPtr->matchLengthSum = 0; for (ml=0; ml<=MaxML; ml++) { U32 const scaleLog = 10; U32 const bitCost = FSE_getMaxNbBits(mlstate.symbolTT, ml); assert(bitCost < scaleLog); optPtr->matchLengthFreq[ml] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; optPtr->matchLengthSum += optPtr->matchLengthFreq[ml]; } } { unsigned of; FSE_CState_t ofstate; FSE_initCState(&ofstate, optPtr->symbolCosts->fse.offcodeCTable); optPtr->offCodeSum = 0; for (of=0; of<=MaxOff; of++) { U32 const scaleLog = 10; U32 const bitCost = FSE_getMaxNbBits(ofstate.symbolTT, of); assert(bitCost < scaleLog); optPtr->offCodeFreq[of] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; optPtr->offCodeSum += optPtr->offCodeFreq[of]; } } } else { /* first block, no dictionary */ assert(optPtr->litFreq != NULL); if (compressedLiterals) { /* base initial cost of literals on direct frequency within src */ unsigned lit = MaxLit; HIST_count_simple(optPtr->litFreq, &lit, src, srcSize); /* use raw first block to init statistics */ optPtr->litSum = ZSTD_downscaleStats(optPtr->litFreq, MaxLit, 8, base_0possible); } { unsigned const baseLLfreqs[MaxLL+1] = { 4, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 }; ZSTD_memcpy(optPtr->litLengthFreq, baseLLfreqs, sizeof(baseLLfreqs)); optPtr->litLengthSum = sum_u32(baseLLfreqs, MaxLL+1); } { unsigned ml; for (ml=0; ml<=MaxML; ml++) optPtr->matchLengthFreq[ml] = 1; } optPtr->matchLengthSum = MaxML+1; { unsigned const baseOFCfreqs[MaxOff+1] = { 6, 2, 1, 1, 2, 3, 4, 4, 4, 3, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 }; ZSTD_memcpy(optPtr->offCodeFreq, baseOFCfreqs, sizeof(baseOFCfreqs)); optPtr->offCodeSum = sum_u32(baseOFCfreqs, MaxOff+1); } } } else { /* new block : scale down accumulated statistics */ if (compressedLiterals) optPtr->litSum = ZSTD_scaleStats(optPtr->litFreq, MaxLit, 12); optPtr->litLengthSum = ZSTD_scaleStats(optPtr->litLengthFreq, MaxLL, 11); optPtr->matchLengthSum = ZSTD_scaleStats(optPtr->matchLengthFreq, MaxML, 11); optPtr->offCodeSum = ZSTD_scaleStats(optPtr->offCodeFreq, MaxOff, 11); } ZSTD_setBasePrices(optPtr, optLevel); } /* ZSTD_rawLiteralsCost() : * price of literals (only) in specified segment (which length can be 0). * does not include price of literalLength symbol */ static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength, const optState_t* const optPtr, int optLevel) { if (litLength == 0) return 0; if (!ZSTD_compressedLiterals(optPtr)) return (litLength << 3) * BITCOST_MULTIPLIER; /* Uncompressed - 8 bytes per literal. */ if (optPtr->priceType == zop_predef) return (litLength*6) * BITCOST_MULTIPLIER; /* 6 bit per literal - no statistic used */ /* dynamic statistics */ { U32 price = optPtr->litSumBasePrice * litLength; U32 const litPriceMax = optPtr->litSumBasePrice - BITCOST_MULTIPLIER; U32 u; assert(optPtr->litSumBasePrice >= BITCOST_MULTIPLIER); for (u=0; u < litLength; u++) { U32 litPrice = WEIGHT(optPtr->litFreq[literals[u]], optLevel); if (UNLIKELY(litPrice > litPriceMax)) litPrice = litPriceMax; price -= litPrice; } return price; } } /* ZSTD_litLengthPrice() : * cost of literalLength symbol */ static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optPtr, int optLevel) { assert(litLength <= ZSTD_BLOCKSIZE_MAX); if (optPtr->priceType == zop_predef) return WEIGHT(litLength, optLevel); /* ZSTD_LLcode() can't compute litLength price for sizes >= ZSTD_BLOCKSIZE_MAX * because it isn't representable in the zstd format. * So instead just pretend it would cost 1 bit more than ZSTD_BLOCKSIZE_MAX - 1. * In such a case, the block would be all literals. */ if (litLength == ZSTD_BLOCKSIZE_MAX) return BITCOST_MULTIPLIER + ZSTD_litLengthPrice(ZSTD_BLOCKSIZE_MAX - 1, optPtr, optLevel); /* dynamic statistics */ { U32 const llCode = ZSTD_LLcode(litLength); return (LL_bits[llCode] * BITCOST_MULTIPLIER) + optPtr->litLengthSumBasePrice - WEIGHT(optPtr->litLengthFreq[llCode], optLevel); } } /* ZSTD_getMatchPrice() : * Provides the cost of the match part (offset + matchLength) of a sequence. * Must be combined with ZSTD_fullLiteralsCost() to get the full cost of a sequence. * @offBase : sumtype, representing an offset or a repcode, and using numeric representation of ZSTD_storeSeq() * @optLevel: when <2, favors small offset for decompression speed (improved cache efficiency) */ FORCE_INLINE_TEMPLATE U32 ZSTD_getMatchPrice(U32 const offBase, U32 const matchLength, const optState_t* const optPtr, int const optLevel) { U32 price; U32 const offCode = ZSTD_highbit32(offBase); U32 const mlBase = matchLength - MINMATCH; assert(matchLength >= MINMATCH); if (optPtr->priceType == zop_predef) /* fixed scheme, does not use statistics */ return WEIGHT(mlBase, optLevel) + ((16 + offCode) * BITCOST_MULTIPLIER); /* emulated offset cost */ /* dynamic statistics */ price = (offCode * BITCOST_MULTIPLIER) + (optPtr->offCodeSumBasePrice - WEIGHT(optPtr->offCodeFreq[offCode], optLevel)); if ((optLevel<2) /*static*/ && offCode >= 20) price += (offCode-19)*2 * BITCOST_MULTIPLIER; /* handicap for long distance offsets, favor decompression speed */ /* match Length */ { U32 const mlCode = ZSTD_MLcode(mlBase); price += (ML_bits[mlCode] * BITCOST_MULTIPLIER) + (optPtr->matchLengthSumBasePrice - WEIGHT(optPtr->matchLengthFreq[mlCode], optLevel)); } price += BITCOST_MULTIPLIER / 5; /* heuristic : make matches a bit more costly to favor less sequences -> faster decompression speed */ DEBUGLOG(8, "ZSTD_getMatchPrice(ml:%u) = %u", matchLength, price); return price; } /* ZSTD_updateStats() : * assumption : literals + litLength <= iend */ static void ZSTD_updateStats(optState_t* const optPtr, U32 litLength, const BYTE* literals, U32 offBase, U32 matchLength) { /* literals */ if (ZSTD_compressedLiterals(optPtr)) { U32 u; for (u=0; u < litLength; u++) optPtr->litFreq[literals[u]] += ZSTD_LITFREQ_ADD; optPtr->litSum += litLength*ZSTD_LITFREQ_ADD; } /* literal Length */ { U32 const llCode = ZSTD_LLcode(litLength); optPtr->litLengthFreq[llCode]++; optPtr->litLengthSum++; } /* offset code : follows storeSeq() numeric representation */ { U32 const offCode = ZSTD_highbit32(offBase); assert(offCode <= MaxOff); optPtr->offCodeFreq[offCode]++; optPtr->offCodeSum++; } /* match Length */ { U32 const mlBase = matchLength - MINMATCH; U32 const mlCode = ZSTD_MLcode(mlBase); optPtr->matchLengthFreq[mlCode]++; optPtr->matchLengthSum++; } } /* ZSTD_readMINMATCH() : * function safe only for comparisons * assumption : memPtr must be at least 4 bytes before end of buffer */ MEM_STATIC U32 ZSTD_readMINMATCH(const void* memPtr, U32 length) { switch (length) { default : case 4 : return MEM_read32(memPtr); case 3 : if (MEM_isLittleEndian()) return MEM_read32(memPtr)<<8; else return MEM_read32(memPtr)>>8; } } /* Update hashTable3 up to ip (excluded) Assumption : always within prefix (i.e. not within extDict) */ static U32 ZSTD_insertAndFindFirstIndexHash3 (const ZSTD_matchState_t* ms, U32* nextToUpdate3, const BYTE* const ip) { U32* const hashTable3 = ms->hashTable3; U32 const hashLog3 = ms->hashLog3; const BYTE* const base = ms->window.base; U32 idx = *nextToUpdate3; U32 const target = (U32)(ip - base); size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3); assert(hashLog3 > 0); while(idx < target) { hashTable3[ZSTD_hash3Ptr(base+idx, hashLog3)] = idx; idx++; } *nextToUpdate3 = target; return hashTable3[hash3]; } /*-************************************* * Binary Tree search ***************************************/ /** ZSTD_insertBt1() : add one or multiple positions to tree. * @param ip assumed <= iend-8 . * @param target The target of ZSTD_updateTree_internal() - we are filling to this position * @return : nb of positions added */ static U32 ZSTD_insertBt1( const ZSTD_matchState_t* ms, const BYTE* const ip, const BYTE* const iend, U32 const target, U32 const mls, const int extDict) { const ZSTD_compressionParameters* const cParams = &ms->cParams; U32* const hashTable = ms->hashTable; U32 const hashLog = cParams->hashLog; size_t const h = ZSTD_hashPtr(ip, hashLog, mls); U32* const bt = ms->chainTable; U32 const btLog = cParams->chainLog - 1; U32 const btMask = (1 << btLog) - 1; U32 matchIndex = hashTable[h]; size_t commonLengthSmaller=0, commonLengthLarger=0; const BYTE* const base = ms->window.base; const BYTE* const dictBase = ms->window.dictBase; const U32 dictLimit = ms->window.dictLimit; const BYTE* const dictEnd = dictBase + dictLimit; const BYTE* const prefixStart = base + dictLimit; const BYTE* match; const U32 curr = (U32)(ip-base); const U32 btLow = btMask >= curr ? 0 : curr - btMask; U32* smallerPtr = bt + 2*(curr&btMask); U32* largerPtr = smallerPtr + 1; U32 dummy32; /* to be nullified at the end */ /* windowLow is based on target because * we only need positions that will be in the window at the end of the tree update. */ U32 const windowLow = ZSTD_getLowestMatchIndex(ms, target, cParams->windowLog); U32 matchEndIdx = curr+8+1; size_t bestLength = 8; U32 nbCompares = 1U << cParams->searchLog; #ifdef ZSTD_C_PREDICT U32 predictedSmall = *(bt + 2*((curr-1)&btMask) + 0); U32 predictedLarge = *(bt + 2*((curr-1)&btMask) + 1); predictedSmall += (predictedSmall>0); predictedLarge += (predictedLarge>0); #endif /* ZSTD_C_PREDICT */ DEBUGLOG(8, "ZSTD_insertBt1 (%u)", curr); assert(curr <= target); assert(ip <= iend-8); /* required for h calculation */ hashTable[h] = curr; /* Update Hash Table */ assert(windowLow > 0); for (; nbCompares && (matchIndex >= windowLow); --nbCompares) { U32* const nextPtr = bt + 2*(matchIndex & btMask); size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ assert(matchIndex < curr); #ifdef ZSTD_C_PREDICT /* note : can create issues when hlog small <= 11 */ const U32* predictPtr = bt + 2*((matchIndex-1) & btMask); /* written this way, as bt is a roll buffer */ if (matchIndex == predictedSmall) { /* no need to check length, result known */ *smallerPtr = matchIndex; if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ smallerPtr = nextPtr+1; /* new "smaller" => larger of match */ matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ predictedSmall = predictPtr[1] + (predictPtr[1]>0); continue; } if (matchIndex == predictedLarge) { *largerPtr = matchIndex; if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ largerPtr = nextPtr; matchIndex = nextPtr[0]; predictedLarge = predictPtr[0] + (predictPtr[0]>0); continue; } #endif if (!extDict || (matchIndex+matchLength >= dictLimit)) { assert(matchIndex+matchLength >= dictLimit); /* might be wrong if actually extDict */ match = base + matchIndex; matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); } else { match = dictBase + matchIndex; matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); if (matchIndex+matchLength >= dictLimit) match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ } if (matchLength > bestLength) { bestLength = matchLength; if (matchLength > matchEndIdx - matchIndex) matchEndIdx = matchIndex + (U32)matchLength; } if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */ } if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */ /* match is smaller than current */ *smallerPtr = matchIndex; /* update smaller idx */ commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */ smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */ matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */ } else { /* match is larger than current */ *largerPtr = matchIndex; commonLengthLarger = matchLength; if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */ largerPtr = nextPtr; matchIndex = nextPtr[0]; } } *smallerPtr = *largerPtr = 0; { U32 positions = 0; if (bestLength > 384) positions = MIN(192, (U32)(bestLength - 384)); /* speed optimization */ assert(matchEndIdx > curr + 8); return MAX(positions, matchEndIdx - (curr + 8)); } } FORCE_INLINE_TEMPLATE void ZSTD_updateTree_internal( ZSTD_matchState_t* ms, const BYTE* const ip, const BYTE* const iend, const U32 mls, const ZSTD_dictMode_e dictMode) { const BYTE* const base = ms->window.base; U32 const target = (U32)(ip - base); U32 idx = ms->nextToUpdate; DEBUGLOG(6, "ZSTD_updateTree_internal, from %u to %u (dictMode:%u)", idx, target, dictMode); while(idx < target) { U32 const forward = ZSTD_insertBt1(ms, base+idx, iend, target, mls, dictMode == ZSTD_extDict); assert(idx < (U32)(idx + forward)); idx += forward; } assert((size_t)(ip - base) <= (size_t)(U32)(-1)); assert((size_t)(iend - base) <= (size_t)(U32)(-1)); ms->nextToUpdate = target; } void ZSTD_updateTree(ZSTD_matchState_t* ms, const BYTE* ip, const BYTE* iend) { ZSTD_updateTree_internal(ms, ip, iend, ms->cParams.minMatch, ZSTD_noDict); } FORCE_INLINE_TEMPLATE U32 ZSTD_insertBtAndGetAllMatches ( ZSTD_match_t* matches, /* store result (found matches) in this table (presumed large enough) */ ZSTD_matchState_t* ms, U32* nextToUpdate3, const BYTE* const ip, const BYTE* const iLimit, const ZSTD_dictMode_e dictMode, const U32 rep[ZSTD_REP_NUM], const U32 ll0, /* tells if associated literal length is 0 or not. This value must be 0 or 1 */ const U32 lengthToBeat, const U32 mls /* template */) { const ZSTD_compressionParameters* const cParams = &ms->cParams; U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); const BYTE* const base = ms->window.base; U32 const curr = (U32)(ip-base); U32 const hashLog = cParams->hashLog; U32 const minMatch = (mls==3) ? 3 : 4; U32* const hashTable = ms->hashTable; size_t const h = ZSTD_hashPtr(ip, hashLog, mls); U32 matchIndex = hashTable[h]; U32* const bt = ms->chainTable; U32 const btLog = cParams->chainLog - 1; U32 const btMask= (1U << btLog) - 1; size_t commonLengthSmaller=0, commonLengthLarger=0; const BYTE* const dictBase = ms->window.dictBase; U32 const dictLimit = ms->window.dictLimit; const BYTE* const dictEnd = dictBase + dictLimit; const BYTE* const prefixStart = base + dictLimit; U32 const btLow = (btMask >= curr) ? 0 : curr - btMask; U32 const windowLow = ZSTD_getLowestMatchIndex(ms, curr, cParams->windowLog); U32 const matchLow = windowLow ? windowLow : 1; U32* smallerPtr = bt + 2*(curr&btMask); U32* largerPtr = bt + 2*(curr&btMask) + 1; U32 matchEndIdx = curr+8+1; /* farthest referenced position of any match => detects repetitive patterns */ U32 dummy32; /* to be nullified at the end */ U32 mnum = 0; U32 nbCompares = 1U << cParams->searchLog; const ZSTD_matchState_t* dms = dictMode == ZSTD_dictMatchState ? ms->dictMatchState : NULL; const ZSTD_compressionParameters* const dmsCParams = dictMode == ZSTD_dictMatchState ? &dms->cParams : NULL; const BYTE* const dmsBase = dictMode == ZSTD_dictMatchState ? dms->window.base : NULL; const BYTE* const dmsEnd = dictMode == ZSTD_dictMatchState ? dms->window.nextSrc : NULL; U32 const dmsHighLimit = dictMode == ZSTD_dictMatchState ? (U32)(dmsEnd - dmsBase) : 0; U32 const dmsLowLimit = dictMode == ZSTD_dictMatchState ? dms->window.lowLimit : 0; U32 const dmsIndexDelta = dictMode == ZSTD_dictMatchState ? windowLow - dmsHighLimit : 0; U32 const dmsHashLog = dictMode == ZSTD_dictMatchState ? dmsCParams->hashLog : hashLog; U32 const dmsBtLog = dictMode == ZSTD_dictMatchState ? dmsCParams->chainLog - 1 : btLog; U32 const dmsBtMask = dictMode == ZSTD_dictMatchState ? (1U << dmsBtLog) - 1 : 0; U32 const dmsBtLow = dictMode == ZSTD_dictMatchState && dmsBtMask < dmsHighLimit - dmsLowLimit ? dmsHighLimit - dmsBtMask : dmsLowLimit; size_t bestLength = lengthToBeat-1; DEBUGLOG(8, "ZSTD_insertBtAndGetAllMatches: current=%u", curr); /* check repCode */ assert(ll0 <= 1); /* necessarily 1 or 0 */ { U32 const lastR = ZSTD_REP_NUM + ll0; U32 repCode; for (repCode = ll0; repCode < lastR; repCode++) { U32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; U32 const repIndex = curr - repOffset; U32 repLen = 0; assert(curr >= dictLimit); if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < curr-dictLimit) { /* equivalent to `curr > repIndex >= dictLimit` */ /* We must validate the repcode offset because when we're using a dictionary the * valid offset range shrinks when the dictionary goes out of bounds. */ if ((repIndex >= windowLow) & (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch))) { repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch; } } else { /* repIndex < dictLimit || repIndex >= curr */ const BYTE* const repMatch = dictMode == ZSTD_dictMatchState ? dmsBase + repIndex - dmsIndexDelta : dictBase + repIndex; assert(curr >= windowLow); if ( dictMode == ZSTD_extDict && ( ((repOffset-1) /*intentional overflow*/ < curr - windowLow) /* equivalent to `curr > repIndex >= windowLow` */ & (((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */) && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch; } if (dictMode == ZSTD_dictMatchState && ( ((repOffset-1) /*intentional overflow*/ < curr - (dmsLowLimit + dmsIndexDelta)) /* equivalent to `curr > repIndex >= dmsLowLimit` */ & ((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */ && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dmsEnd, prefixStart) + minMatch; } } /* save longer solution */ if (repLen > bestLength) { DEBUGLOG(8, "found repCode %u (ll0:%u, offset:%u) of length %u", repCode, ll0, repOffset, repLen); bestLength = repLen; matches[mnum].off = REPCODE_TO_OFFBASE(repCode - ll0 + 1); /* expect value between 1 and 3 */ matches[mnum].len = (U32)repLen; mnum++; if ( (repLen > sufficient_len) | (ip+repLen == iLimit) ) { /* best possible */ return mnum; } } } } /* HC3 match finder */ if ((mls == 3) /*static*/ && (bestLength < mls)) { U32 const matchIndex3 = ZSTD_insertAndFindFirstIndexHash3(ms, nextToUpdate3, ip); if ((matchIndex3 >= matchLow) & (curr - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) { size_t mlen; if ((dictMode == ZSTD_noDict) /*static*/ || (dictMode == ZSTD_dictMatchState) /*static*/ || (matchIndex3 >= dictLimit)) { const BYTE* const match = base + matchIndex3; mlen = ZSTD_count(ip, match, iLimit); } else { const BYTE* const match = dictBase + matchIndex3; mlen = ZSTD_count_2segments(ip, match, iLimit, dictEnd, prefixStart); } /* save best solution */ if (mlen >= mls /* == 3 > bestLength */) { DEBUGLOG(8, "found small match with hlog3, of length %u", (U32)mlen); bestLength = mlen; assert(curr > matchIndex3); assert(mnum==0); /* no prior solution */ matches[0].off = OFFSET_TO_OFFBASE(curr - matchIndex3); matches[0].len = (U32)mlen; mnum = 1; if ( (mlen > sufficient_len) | (ip+mlen == iLimit) ) { /* best possible length */ ms->nextToUpdate = curr+1; /* skip insertion */ return 1; } } } /* no dictMatchState lookup: dicts don't have a populated HC3 table */ } /* if (mls == 3) */ hashTable[h] = curr; /* Update Hash Table */ for (; nbCompares && (matchIndex >= matchLow); --nbCompares) { U32* const nextPtr = bt + 2*(matchIndex & btMask); const BYTE* match; size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ assert(curr > matchIndex); if ((dictMode == ZSTD_noDict) || (dictMode == ZSTD_dictMatchState) || (matchIndex+matchLength >= dictLimit)) { assert(matchIndex+matchLength >= dictLimit); /* ensure the condition is correct when !extDict */ match = base + matchIndex; if (matchIndex >= dictLimit) assert(memcmp(match, ip, matchLength) == 0); /* ensure early section of match is equal as expected */ matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit); } else { match = dictBase + matchIndex; assert(memcmp(match, ip, matchLength) == 0); /* ensure early section of match is equal as expected */ matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart); if (matchIndex+matchLength >= dictLimit) match = base + matchIndex; /* prepare for match[matchLength] read */ } if (matchLength > bestLength) { DEBUGLOG(8, "found match of length %u at distance %u (offBase=%u)", (U32)matchLength, curr - matchIndex, OFFSET_TO_OFFBASE(curr - matchIndex)); assert(matchEndIdx > matchIndex); if (matchLength > matchEndIdx - matchIndex) matchEndIdx = matchIndex + (U32)matchLength; bestLength = matchLength; matches[mnum].off = OFFSET_TO_OFFBASE(curr - matchIndex); matches[mnum].len = (U32)matchLength; mnum++; if ( (matchLength > ZSTD_OPT_NUM) | (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) { if (dictMode == ZSTD_dictMatchState) nbCompares = 0; /* break should also skip searching dms */ break; /* drop, to preserve bt consistency (miss a little bit of compression) */ } } if (match[matchLength] < ip[matchLength]) { /* match smaller than current */ *smallerPtr = matchIndex; /* update smaller idx */ commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ smallerPtr = nextPtr+1; /* new candidate => larger than match, which was smaller than current */ matchIndex = nextPtr[1]; /* new matchIndex, larger than previous, closer to current */ } else { *largerPtr = matchIndex; commonLengthLarger = matchLength; if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ largerPtr = nextPtr; matchIndex = nextPtr[0]; } } *smallerPtr = *largerPtr = 0; assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ if (dictMode == ZSTD_dictMatchState && nbCompares) { size_t const dmsH = ZSTD_hashPtr(ip, dmsHashLog, mls); U32 dictMatchIndex = dms->hashTable[dmsH]; const U32* const dmsBt = dms->chainTable; commonLengthSmaller = commonLengthLarger = 0; for (; nbCompares && (dictMatchIndex > dmsLowLimit); --nbCompares) { const U32* const nextPtr = dmsBt + 2*(dictMatchIndex & dmsBtMask); size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ const BYTE* match = dmsBase + dictMatchIndex; matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dmsEnd, prefixStart); if (dictMatchIndex+matchLength >= dmsHighLimit) match = base + dictMatchIndex + dmsIndexDelta; /* to prepare for next usage of match[matchLength] */ if (matchLength > bestLength) { matchIndex = dictMatchIndex + dmsIndexDelta; DEBUGLOG(8, "found dms match of length %u at distance %u (offBase=%u)", (U32)matchLength, curr - matchIndex, OFFSET_TO_OFFBASE(curr - matchIndex)); if (matchLength > matchEndIdx - matchIndex) matchEndIdx = matchIndex + (U32)matchLength; bestLength = matchLength; matches[mnum].off = OFFSET_TO_OFFBASE(curr - matchIndex); matches[mnum].len = (U32)matchLength; mnum++; if ( (matchLength > ZSTD_OPT_NUM) | (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) { break; /* drop, to guarantee consistency (miss a little bit of compression) */ } } if (dictMatchIndex <= dmsBtLow) { break; } /* beyond tree size, stop the search */ if (match[matchLength] < ip[matchLength]) { commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ } else { /* match is larger than current */ commonLengthLarger = matchLength; dictMatchIndex = nextPtr[0]; } } } /* if (dictMode == ZSTD_dictMatchState) */ assert(matchEndIdx > curr+8); ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ return mnum; } typedef U32 (*ZSTD_getAllMatchesFn)( ZSTD_match_t*, ZSTD_matchState_t*, U32*, const BYTE*, const BYTE*, const U32 rep[ZSTD_REP_NUM], U32 const ll0, U32 const lengthToBeat); FORCE_INLINE_TEMPLATE U32 ZSTD_btGetAllMatches_internal( ZSTD_match_t* matches, ZSTD_matchState_t* ms, U32* nextToUpdate3, const BYTE* ip, const BYTE* const iHighLimit, const U32 rep[ZSTD_REP_NUM], U32 const ll0, U32 const lengthToBeat, const ZSTD_dictMode_e dictMode, const U32 mls) { assert(BOUNDED(3, ms->cParams.minMatch, 6) == mls); DEBUGLOG(8, "ZSTD_BtGetAllMatches(dictMode=%d, mls=%u)", (int)dictMode, mls); if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */ ZSTD_updateTree_internal(ms, ip, iHighLimit, mls, dictMode); return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, mls); } #define ZSTD_BT_GET_ALL_MATCHES_FN(dictMode, mls) ZSTD_btGetAllMatches_##dictMode##_##mls #define GEN_ZSTD_BT_GET_ALL_MATCHES_(dictMode, mls) \ static U32 ZSTD_BT_GET_ALL_MATCHES_FN(dictMode, mls)( \ ZSTD_match_t* matches, \ ZSTD_matchState_t* ms, \ U32* nextToUpdate3, \ const BYTE* ip, \ const BYTE* const iHighLimit, \ const U32 rep[ZSTD_REP_NUM], \ U32 const ll0, \ U32 const lengthToBeat) \ { \ return ZSTD_btGetAllMatches_internal( \ matches, ms, nextToUpdate3, ip, iHighLimit, \ rep, ll0, lengthToBeat, ZSTD_##dictMode, mls); \ } #define GEN_ZSTD_BT_GET_ALL_MATCHES(dictMode) \ GEN_ZSTD_BT_GET_ALL_MATCHES_(dictMode, 3) \ GEN_ZSTD_BT_GET_ALL_MATCHES_(dictMode, 4) \ GEN_ZSTD_BT_GET_ALL_MATCHES_(dictMode, 5) \ GEN_ZSTD_BT_GET_ALL_MATCHES_(dictMode, 6) GEN_ZSTD_BT_GET_ALL_MATCHES(noDict) GEN_ZSTD_BT_GET_ALL_MATCHES(extDict) GEN_ZSTD_BT_GET_ALL_MATCHES(dictMatchState) #define ZSTD_BT_GET_ALL_MATCHES_ARRAY(dictMode) \ { \ ZSTD_BT_GET_ALL_MATCHES_FN(dictMode, 3), \ ZSTD_BT_GET_ALL_MATCHES_FN(dictMode, 4), \ ZSTD_BT_GET_ALL_MATCHES_FN(dictMode, 5), \ ZSTD_BT_GET_ALL_MATCHES_FN(dictMode, 6) \ } static ZSTD_getAllMatchesFn ZSTD_selectBtGetAllMatches(ZSTD_matchState_t const* ms, ZSTD_dictMode_e const dictMode) { ZSTD_getAllMatchesFn const getAllMatchesFns[3][4] = { ZSTD_BT_GET_ALL_MATCHES_ARRAY(noDict), ZSTD_BT_GET_ALL_MATCHES_ARRAY(extDict), ZSTD_BT_GET_ALL_MATCHES_ARRAY(dictMatchState) }; U32 const mls = BOUNDED(3, ms->cParams.minMatch, 6); assert((U32)dictMode < 3); assert(mls - 3 < 4); return getAllMatchesFns[(int)dictMode][mls - 3]; } /************************* * LDM helper functions * *************************/ /* Struct containing info needed to make decision about ldm inclusion */ typedef struct { rawSeqStore_t seqStore; /* External match candidates store for this block */ U32 startPosInBlock; /* Start position of the current match candidate */ U32 endPosInBlock; /* End position of the current match candidate */ U32 offset; /* Offset of the match candidate */ } ZSTD_optLdm_t; /* ZSTD_optLdm_skipRawSeqStoreBytes(): * Moves forward in @rawSeqStore by @nbBytes, * which will update the fields 'pos' and 'posInSequence'. */ static void ZSTD_optLdm_skipRawSeqStoreBytes(rawSeqStore_t* rawSeqStore, size_t nbBytes) { U32 currPos = (U32)(rawSeqStore->posInSequence + nbBytes); while (currPos && rawSeqStore->pos < rawSeqStore->size) { rawSeq currSeq = rawSeqStore->seq[rawSeqStore->pos]; if (currPos >= currSeq.litLength + currSeq.matchLength) { currPos -= currSeq.litLength + currSeq.matchLength; rawSeqStore->pos++; } else { rawSeqStore->posInSequence = currPos; break; } } if (currPos == 0 || rawSeqStore->pos == rawSeqStore->size) { rawSeqStore->posInSequence = 0; } } /* ZSTD_opt_getNextMatchAndUpdateSeqStore(): * Calculates the beginning and end of the next match in the current block. * Updates 'pos' and 'posInSequence' of the ldmSeqStore. */ static void ZSTD_opt_getNextMatchAndUpdateSeqStore(ZSTD_optLdm_t* optLdm, U32 currPosInBlock, U32 blockBytesRemaining) { rawSeq currSeq; U32 currBlockEndPos; U32 literalsBytesRemaining; U32 matchBytesRemaining; /* Setting match end position to MAX to ensure we never use an LDM during this block */ if (optLdm->seqStore.size == 0 || optLdm->seqStore.pos >= optLdm->seqStore.size) { optLdm->startPosInBlock = UINT_MAX; optLdm->endPosInBlock = UINT_MAX; return; } /* Calculate appropriate bytes left in matchLength and litLength * after adjusting based on ldmSeqStore->posInSequence */ currSeq = optLdm->seqStore.seq[optLdm->seqStore.pos]; assert(optLdm->seqStore.posInSequence <= currSeq.litLength + currSeq.matchLength); currBlockEndPos = currPosInBlock + blockBytesRemaining; literalsBytesRemaining = (optLdm->seqStore.posInSequence < currSeq.litLength) ? currSeq.litLength - (U32)optLdm->seqStore.posInSequence : 0; matchBytesRemaining = (literalsBytesRemaining == 0) ? currSeq.matchLength - ((U32)optLdm->seqStore.posInSequence - currSeq.litLength) : currSeq.matchLength; /* If there are more literal bytes than bytes remaining in block, no ldm is possible */ if (literalsBytesRemaining >= blockBytesRemaining) { optLdm->startPosInBlock = UINT_MAX; optLdm->endPosInBlock = UINT_MAX; ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, blockBytesRemaining); return; } /* Matches may be < MINMATCH by this process. In that case, we will reject them when we are deciding whether or not to add the ldm */ optLdm->startPosInBlock = currPosInBlock + literalsBytesRemaining; optLdm->endPosInBlock = optLdm->startPosInBlock + matchBytesRemaining; optLdm->offset = currSeq.offset; if (optLdm->endPosInBlock > currBlockEndPos) { /* Match ends after the block ends, we can't use the whole match */ optLdm->endPosInBlock = currBlockEndPos; ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, currBlockEndPos - currPosInBlock); } else { /* Consume nb of bytes equal to size of sequence left */ ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, literalsBytesRemaining + matchBytesRemaining); } } /* ZSTD_optLdm_maybeAddMatch(): * Adds a match if it's long enough, * based on it's 'matchStartPosInBlock' and 'matchEndPosInBlock', * into 'matches'. Maintains the correct ordering of 'matches'. */ static void ZSTD_optLdm_maybeAddMatch(ZSTD_match_t* matches, U32* nbMatches, const ZSTD_optLdm_t* optLdm, U32 currPosInBlock) { U32 const posDiff = currPosInBlock - optLdm->startPosInBlock; /* Note: ZSTD_match_t actually contains offBase and matchLength (before subtracting MINMATCH) */ U32 const candidateMatchLength = optLdm->endPosInBlock - optLdm->startPosInBlock - posDiff; /* Ensure that current block position is not outside of the match */ if (currPosInBlock < optLdm->startPosInBlock || currPosInBlock >= optLdm->endPosInBlock || candidateMatchLength < MINMATCH) { return; } if (*nbMatches == 0 || ((candidateMatchLength > matches[*nbMatches-1].len) && *nbMatches < ZSTD_OPT_NUM)) { U32 const candidateOffBase = OFFSET_TO_OFFBASE(optLdm->offset); DEBUGLOG(6, "ZSTD_optLdm_maybeAddMatch(): Adding ldm candidate match (offBase: %u matchLength %u) at block position=%u", candidateOffBase, candidateMatchLength, currPosInBlock); matches[*nbMatches].len = candidateMatchLength; matches[*nbMatches].off = candidateOffBase; (*nbMatches)++; } } /* ZSTD_optLdm_processMatchCandidate(): * Wrapper function to update ldm seq store and call ldm functions as necessary. */ static void ZSTD_optLdm_processMatchCandidate(ZSTD_optLdm_t* optLdm, ZSTD_match_t* matches, U32* nbMatches, U32 currPosInBlock, U32 remainingBytes) { if (optLdm->seqStore.size == 0 || optLdm->seqStore.pos >= optLdm->seqStore.size) { return; } if (currPosInBlock >= optLdm->endPosInBlock) { if (currPosInBlock > optLdm->endPosInBlock) { /* The position at which ZSTD_optLdm_processMatchCandidate() is called is not necessarily * at the end of a match from the ldm seq store, and will often be some bytes * over beyond matchEndPosInBlock. As such, we need to correct for these "overshoots" */ U32 const posOvershoot = currPosInBlock - optLdm->endPosInBlock; ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, posOvershoot); } ZSTD_opt_getNextMatchAndUpdateSeqStore(optLdm, currPosInBlock, remainingBytes); } ZSTD_optLdm_maybeAddMatch(matches, nbMatches, optLdm, currPosInBlock); } /*-******************************* * Optimal parser *********************************/ static U32 ZSTD_totalLen(ZSTD_optimal_t sol) { return sol.litlen + sol.mlen; } #if 0 /* debug */ static void listStats(const U32* table, int lastEltID) { int const nbElts = lastEltID + 1; int enb; for (enb=0; enb < nbElts; enb++) { (void)table; /* RAWLOG(2, "%3i:%3i, ", enb, table[enb]); */ RAWLOG(2, "%4i,", table[enb]); } RAWLOG(2, " \n"); } #endif FORCE_INLINE_TEMPLATE size_t ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize, const int optLevel, const ZSTD_dictMode_e dictMode) { optState_t* const optStatePtr = &ms->opt; const BYTE* const istart = (const BYTE*)src; const BYTE* ip = istart; const BYTE* anchor = istart; const BYTE* const iend = istart + srcSize; const BYTE* const ilimit = iend - 8; const BYTE* const base = ms->window.base; const BYTE* const prefixStart = base + ms->window.dictLimit; const ZSTD_compressionParameters* const cParams = &ms->cParams; ZSTD_getAllMatchesFn getAllMatches = ZSTD_selectBtGetAllMatches(ms, dictMode); U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); U32 const minMatch = (cParams->minMatch == 3) ? 3 : 4; U32 nextToUpdate3 = ms->nextToUpdate; ZSTD_optimal_t* const opt = optStatePtr->priceTable; ZSTD_match_t* const matches = optStatePtr->matchTable; ZSTD_optimal_t lastSequence; ZSTD_optLdm_t optLdm; optLdm.seqStore = ms->ldmSeqStore ? *ms->ldmSeqStore : kNullRawSeqStore; optLdm.endPosInBlock = optLdm.startPosInBlock = optLdm.offset = 0; ZSTD_opt_getNextMatchAndUpdateSeqStore(&optLdm, (U32)(ip-istart), (U32)(iend-ip)); /* init */ DEBUGLOG(5, "ZSTD_compressBlock_opt_generic: current=%u, prefix=%u, nextToUpdate=%u", (U32)(ip - base), ms->window.dictLimit, ms->nextToUpdate); assert(optLevel <= 2); ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize, optLevel); ip += (ip==prefixStart); /* Match Loop */ while (ip < ilimit) { U32 cur, last_pos = 0; /* find first match */ { U32 const litlen = (U32)(ip - anchor); U32 const ll0 = !litlen; U32 nbMatches = getAllMatches(matches, ms, &nextToUpdate3, ip, iend, rep, ll0, minMatch); ZSTD_optLdm_processMatchCandidate(&optLdm, matches, &nbMatches, (U32)(ip-istart), (U32)(iend - ip)); if (!nbMatches) { ip++; continue; } /* initialize opt[0] */ { U32 i ; for (i=0; i immediate encoding */ { U32 const maxML = matches[nbMatches-1].len; U32 const maxOffBase = matches[nbMatches-1].off; DEBUGLOG(6, "found %u matches of maxLength=%u and maxOffBase=%u at cPos=%u => start new series", nbMatches, maxML, maxOffBase, (U32)(ip-prefixStart)); if (maxML > sufficient_len) { lastSequence.litlen = litlen; lastSequence.mlen = maxML; lastSequence.off = maxOffBase; DEBUGLOG(6, "large match (%u>%u), immediate encoding", maxML, sufficient_len); cur = 0; last_pos = ZSTD_totalLen(lastSequence); goto _shortestPath; } } /* set prices for first matches starting position == 0 */ assert(opt[0].price >= 0); { U32 const literalsPrice = (U32)opt[0].price + ZSTD_litLengthPrice(0, optStatePtr, optLevel); U32 pos; U32 matchNb; for (pos = 1; pos < minMatch; pos++) { opt[pos].price = ZSTD_MAX_PRICE; /* mlen, litlen and price will be fixed during forward scanning */ } for (matchNb = 0; matchNb < nbMatches; matchNb++) { U32 const offBase = matches[matchNb].off; U32 const end = matches[matchNb].len; for ( ; pos <= end ; pos++ ) { U32 const matchPrice = ZSTD_getMatchPrice(offBase, pos, optStatePtr, optLevel); U32 const sequencePrice = literalsPrice + matchPrice; DEBUGLOG(7, "rPos:%u => set initial price : %.2f", pos, ZSTD_fCost((int)sequencePrice)); opt[pos].mlen = pos; opt[pos].off = offBase; opt[pos].litlen = litlen; opt[pos].price = (int)sequencePrice; } } last_pos = pos-1; } } /* check further positions */ for (cur = 1; cur <= last_pos; cur++) { const BYTE* const inr = ip + cur; assert(cur < ZSTD_OPT_NUM); DEBUGLOG(7, "cPos:%zi==rPos:%u", inr-istart, cur) /* Fix current position with one literal if cheaper */ { U32 const litlen = (opt[cur-1].mlen == 0) ? opt[cur-1].litlen + 1 : 1; int const price = opt[cur-1].price + (int)ZSTD_rawLiteralsCost(ip+cur-1, 1, optStatePtr, optLevel) + (int)ZSTD_litLengthPrice(litlen, optStatePtr, optLevel) - (int)ZSTD_litLengthPrice(litlen-1, optStatePtr, optLevel); assert(price < 1000000000); /* overflow check */ if (price <= opt[cur].price) { DEBUGLOG(7, "cPos:%zi==rPos:%u : better price (%.2f<=%.2f) using literal (ll==%u) (hist:%u,%u,%u)", inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), litlen, opt[cur-1].rep[0], opt[cur-1].rep[1], opt[cur-1].rep[2]); opt[cur].mlen = 0; opt[cur].off = 0; opt[cur].litlen = litlen; opt[cur].price = price; } else { DEBUGLOG(7, "cPos:%zi==rPos:%u : literal would cost more (%.2f>%.2f) (hist:%u,%u,%u)", inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), opt[cur].rep[0], opt[cur].rep[1], opt[cur].rep[2]); } } /* Set the repcodes of the current position. We must do it here * because we rely on the repcodes of the 2nd to last sequence being * correct to set the next chunks repcodes during the backward * traversal. */ ZSTD_STATIC_ASSERT(sizeof(opt[cur].rep) == sizeof(repcodes_t)); assert(cur >= opt[cur].mlen); if (opt[cur].mlen != 0) { U32 const prev = cur - opt[cur].mlen; repcodes_t const newReps = ZSTD_newRep(opt[prev].rep, opt[cur].off, opt[cur].litlen==0); ZSTD_memcpy(opt[cur].rep, &newReps, sizeof(repcodes_t)); } else { ZSTD_memcpy(opt[cur].rep, opt[cur - 1].rep, sizeof(repcodes_t)); } /* last match must start at a minimum distance of 8 from oend */ if (inr > ilimit) continue; if (cur == last_pos) break; if ( (optLevel==0) /*static_test*/ && (opt[cur+1].price <= opt[cur].price + (BITCOST_MULTIPLIER/2)) ) { DEBUGLOG(7, "move to next rPos:%u : price is <=", cur+1); continue; /* skip unpromising positions; about ~+6% speed, -0.01 ratio */ } assert(opt[cur].price >= 0); { U32 const ll0 = (opt[cur].mlen != 0); U32 const litlen = (opt[cur].mlen == 0) ? opt[cur].litlen : 0; U32 const previousPrice = (U32)opt[cur].price; U32 const basePrice = previousPrice + ZSTD_litLengthPrice(0, optStatePtr, optLevel); U32 nbMatches = getAllMatches(matches, ms, &nextToUpdate3, inr, iend, opt[cur].rep, ll0, minMatch); U32 matchNb; ZSTD_optLdm_processMatchCandidate(&optLdm, matches, &nbMatches, (U32)(inr-istart), (U32)(iend-inr)); if (!nbMatches) { DEBUGLOG(7, "rPos:%u : no match found", cur); continue; } { U32 const maxML = matches[nbMatches-1].len; DEBUGLOG(7, "cPos:%zi==rPos:%u, found %u matches, of maxLength=%u", inr-istart, cur, nbMatches, maxML); if ( (maxML > sufficient_len) || (cur + maxML >= ZSTD_OPT_NUM) ) { lastSequence.mlen = maxML; lastSequence.off = matches[nbMatches-1].off; lastSequence.litlen = litlen; cur -= (opt[cur].mlen==0) ? opt[cur].litlen : 0; /* last sequence is actually only literals, fix cur to last match - note : may underflow, in which case, it's first sequence, and it's okay */ last_pos = cur + ZSTD_totalLen(lastSequence); if (cur > ZSTD_OPT_NUM) cur = 0; /* underflow => first match */ goto _shortestPath; } } /* set prices using matches found at position == cur */ for (matchNb = 0; matchNb < nbMatches; matchNb++) { U32 const offset = matches[matchNb].off; U32 const lastML = matches[matchNb].len; U32 const startML = (matchNb>0) ? matches[matchNb-1].len+1 : minMatch; U32 mlen; DEBUGLOG(7, "testing match %u => offBase=%4u, mlen=%2u, llen=%2u", matchNb, matches[matchNb].off, lastML, litlen); for (mlen = lastML; mlen >= startML; mlen--) { /* scan downward */ U32 const pos = cur + mlen; int const price = (int)basePrice + (int)ZSTD_getMatchPrice(offset, mlen, optStatePtr, optLevel); if ((pos > last_pos) || (price < opt[pos].price)) { DEBUGLOG(7, "rPos:%u (ml=%2u) => new better price (%.2f<%.2f)", pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price)); while (last_pos < pos) { opt[last_pos+1].price = ZSTD_MAX_PRICE; last_pos++; } /* fill empty positions */ opt[pos].mlen = mlen; opt[pos].off = offset; opt[pos].litlen = litlen; opt[pos].price = price; } else { DEBUGLOG(7, "rPos:%u (ml=%2u) => new price is worse (%.2f>=%.2f)", pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price)); if (optLevel==0) break; /* early update abort; gets ~+10% speed for about -0.01 ratio loss */ } } } } } /* for (cur = 1; cur <= last_pos; cur++) */ lastSequence = opt[last_pos]; cur = last_pos > ZSTD_totalLen(lastSequence) ? last_pos - ZSTD_totalLen(lastSequence) : 0; /* single sequence, and it starts before `ip` */ assert(cur < ZSTD_OPT_NUM); /* control overflow*/ _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */ assert(opt[0].mlen == 0); /* Set the next chunk's repcodes based on the repcodes of the beginning * of the last match, and the last sequence. This avoids us having to * update them while traversing the sequences. */ if (lastSequence.mlen != 0) { repcodes_t const reps = ZSTD_newRep(opt[cur].rep, lastSequence.off, lastSequence.litlen==0); ZSTD_memcpy(rep, &reps, sizeof(reps)); } else { ZSTD_memcpy(rep, opt[cur].rep, sizeof(repcodes_t)); } { U32 const storeEnd = cur + 1; U32 storeStart = storeEnd; U32 seqPos = cur; DEBUGLOG(6, "start reverse traversal (last_pos:%u, cur:%u)", last_pos, cur); (void)last_pos; assert(storeEnd < ZSTD_OPT_NUM); DEBUGLOG(6, "last sequence copied into pos=%u (llen=%u,mlen=%u,ofc=%u)", storeEnd, lastSequence.litlen, lastSequence.mlen, lastSequence.off); opt[storeEnd] = lastSequence; while (seqPos > 0) { U32 const backDist = ZSTD_totalLen(opt[seqPos]); storeStart--; DEBUGLOG(6, "sequence from rPos=%u copied into pos=%u (llen=%u,mlen=%u,ofc=%u)", seqPos, storeStart, opt[seqPos].litlen, opt[seqPos].mlen, opt[seqPos].off); opt[storeStart] = opt[seqPos]; seqPos = (seqPos > backDist) ? seqPos - backDist : 0; } /* save sequences */ DEBUGLOG(6, "sending selected sequences into seqStore") { U32 storePos; for (storePos=storeStart; storePos <= storeEnd; storePos++) { U32 const llen = opt[storePos].litlen; U32 const mlen = opt[storePos].mlen; U32 const offBase = opt[storePos].off; U32 const advance = llen + mlen; DEBUGLOG(6, "considering seq starting at %zi, llen=%u, mlen=%u", anchor - istart, (unsigned)llen, (unsigned)mlen); if (mlen==0) { /* only literals => must be last "sequence", actually starting a new stream of sequences */ assert(storePos == storeEnd); /* must be last sequence */ ip = anchor + llen; /* last "sequence" is a bunch of literals => don't progress anchor */ continue; /* will finish */ } assert(anchor + llen <= iend); ZSTD_updateStats(optStatePtr, llen, anchor, offBase, mlen); ZSTD_storeSeq(seqStore, llen, anchor, iend, offBase, mlen); anchor += advance; ip = anchor; } } ZSTD_setBasePrices(optStatePtr, optLevel); } } /* while (ip < ilimit) */ /* Return the last literals size */ return (size_t)(iend - anchor); } static size_t ZSTD_compressBlock_opt0( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize, const ZSTD_dictMode_e dictMode) { return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /* optLevel */, dictMode); } static size_t ZSTD_compressBlock_opt2( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize, const ZSTD_dictMode_e dictMode) { return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /* optLevel */, dictMode); } size_t ZSTD_compressBlock_btopt( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize) { DEBUGLOG(5, "ZSTD_compressBlock_btopt"); return ZSTD_compressBlock_opt0(ms, seqStore, rep, src, srcSize, ZSTD_noDict); } /* ZSTD_initStats_ultra(): * make a first compression pass, just to seed stats with more accurate starting values. * only works on first block, with no dictionary and no ldm. * this function cannot error out, its narrow contract must be respected. */ static void ZSTD_initStats_ultra(ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize) { U32 tmpRep[ZSTD_REP_NUM]; /* updated rep codes will sink here */ ZSTD_memcpy(tmpRep, rep, sizeof(tmpRep)); DEBUGLOG(4, "ZSTD_initStats_ultra (srcSize=%zu)", srcSize); assert(ms->opt.litLengthSum == 0); /* first block */ assert(seqStore->sequences == seqStore->sequencesStart); /* no ldm */ assert(ms->window.dictLimit == ms->window.lowLimit); /* no dictionary */ assert(ms->window.dictLimit - ms->nextToUpdate <= 1); /* no prefix (note: intentional overflow, defined as 2-complement) */ ZSTD_compressBlock_opt2(ms, seqStore, tmpRep, src, srcSize, ZSTD_noDict); /* generate stats into ms->opt*/ /* invalidate first scan from history, only keep entropy stats */ ZSTD_resetSeqStore(seqStore); ms->window.base -= srcSize; ms->window.dictLimit += (U32)srcSize; ms->window.lowLimit = ms->window.dictLimit; ms->nextToUpdate = ms->window.dictLimit; } size_t ZSTD_compressBlock_btultra( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize) { DEBUGLOG(5, "ZSTD_compressBlock_btultra (srcSize=%zu)", srcSize); return ZSTD_compressBlock_opt2(ms, seqStore, rep, src, srcSize, ZSTD_noDict); } size_t ZSTD_compressBlock_btultra2( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize) { U32 const curr = (U32)((const BYTE*)src - ms->window.base); DEBUGLOG(5, "ZSTD_compressBlock_btultra2 (srcSize=%zu)", srcSize); /* 2-passes strategy: * this strategy makes a first pass over first block to collect statistics * in order to seed next round's statistics with it. * After 1st pass, function forgets history, and starts a new block. * Consequently, this can only work if no data has been previously loaded in tables, * aka, no dictionary, no prefix, no ldm preprocessing. * The compression ratio gain is generally small (~0.5% on first block), ** the cost is 2x cpu time on first block. */ assert(srcSize <= ZSTD_BLOCKSIZE_MAX); if ( (ms->opt.litLengthSum==0) /* first block */ && (seqStore->sequences == seqStore->sequencesStart) /* no ldm */ && (ms->window.dictLimit == ms->window.lowLimit) /* no dictionary */ && (curr == ms->window.dictLimit) /* start of frame, nothing already loaded nor skipped */ && (srcSize > ZSTD_PREDEF_THRESHOLD) /* input large enough to not employ default stats */ ) { ZSTD_initStats_ultra(ms, seqStore, rep, src, srcSize); } return ZSTD_compressBlock_opt2(ms, seqStore, rep, src, srcSize, ZSTD_noDict); } size_t ZSTD_compressBlock_btopt_dictMatchState( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize) { return ZSTD_compressBlock_opt0(ms, seqStore, rep, src, srcSize, ZSTD_dictMatchState); } size_t ZSTD_compressBlock_btultra_dictMatchState( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize) { return ZSTD_compressBlock_opt2(ms, seqStore, rep, src, srcSize, ZSTD_dictMatchState); } size_t ZSTD_compressBlock_btopt_extDict( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize) { return ZSTD_compressBlock_opt0(ms, seqStore, rep, src, srcSize, ZSTD_extDict); } size_t ZSTD_compressBlock_btultra_extDict( ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], const void* src, size_t srcSize) { return ZSTD_compressBlock_opt2(ms, seqStore, rep, src, srcSize, ZSTD_extDict); } /* note : no btultra2 variant for extDict nor dictMatchState, * because btultra2 is not meant to work with dictionaries * and is only specific for the first block (no prefix) */ option> Nextcloud server, a safe home for all your data: https://github.com/nextcloud/serverwww-data
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