| /* |
| * Copyright (c) Przemyslaw Skibinski, 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. |
| */ |
| |
| #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_FREQ_DIV 4 /* log factor when using previous stats to init next stats */ |
| #define ZSTD_MAX_PRICE (1<<30) |
| |
| #define ZSTD_PREDEF_THRESHOLD 1024 /* 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 */ |
| # define BITCOST_ACCURACY 0 |
| # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) |
| # define WEIGHT(stat) ((void)opt, ZSTD_bitWeight(stat)) |
| #elif 0 /* fractional bit accuracy */ |
| # 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 |
| |
| MEM_STATIC U32 ZSTD_bitWeight(U32 stat) |
| { |
| return (ZSTD_highbit32(stat+1) * BITCOST_MULTIPLIER); |
| } |
| |
| MEM_STATIC U32 ZSTD_fracWeight(U32 rawStat) |
| { |
| U32 const stat = rawStat + 1; |
| U32 const hb = ZSTD_highbit32(stat); |
| U32 const BWeight = hb * BITCOST_MULTIPLIER; |
| 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(U32 price) |
| { |
| return (double)price / (BITCOST_MULTIPLIER*8); |
| } |
| #endif |
| |
| static int ZSTD_compressedLiterals(optState_t const* const optPtr) |
| { |
| return optPtr->literalCompressionMode != ZSTD_lcm_uncompressed; |
| } |
| |
| 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); |
| } |
| |
| |
| /* ZSTD_downscaleStat() : |
| * reduce all elements in table by a factor 2^(ZSTD_FREQ_DIV+malus) |
| * return the resulting sum of elements */ |
| static U32 ZSTD_downscaleStat(unsigned* table, U32 lastEltIndex, int malus) |
| { |
| U32 s, sum=0; |
| DEBUGLOG(5, "ZSTD_downscaleStat (nbElts=%u)", (unsigned)lastEltIndex+1); |
| assert(ZSTD_FREQ_DIV+malus > 0 && ZSTD_FREQ_DIV+malus < 31); |
| for (s=0; s<lastEltIndex+1; s++) { |
| table[s] = 1 + (table[s] >> (ZSTD_FREQ_DIV+malus)); |
| sum += table[s]; |
| } |
| return sum; |
| } |
| |
| /* ZSTD_rescaleFreqs() : |
| * if first block (detected by optPtr->litLengthSum == 0) : init statistics |
| * take hints from dictionary if there is one |
| * or init from zero, using src for literals stats, or flat 1 for match 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) { /* first block : init */ |
| if (srcSize <= ZSTD_PREDEF_THRESHOLD) { /* heuristic */ |
| DEBUGLOG(5, "(srcSize <= ZSTD_PREDEF_THRESHOLD) => zop_predef"); |
| optPtr->priceType = zop_predef; |
| } |
| |
| assert(optPtr->symbolCosts != NULL); |
| if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid) { |
| /* huffman table presumed generated by dictionary */ |
| optPtr->priceType = zop_dynamic; |
| |
| if (compressedLiterals) { |
| 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_getNbBits(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 { /* not a dictionary */ |
| |
| assert(optPtr->litFreq != NULL); |
| if (compressedLiterals) { |
| unsigned lit = MaxLit; |
| HIST_count_simple(optPtr->litFreq, &lit, src, srcSize); /* use raw first block to init statistics */ |
| optPtr->litSum = ZSTD_downscaleStat(optPtr->litFreq, MaxLit, 1); |
| } |
| |
| { unsigned ll; |
| for (ll=0; ll<=MaxLL; ll++) |
| optPtr->litLengthFreq[ll] = 1; |
| } |
| optPtr->litLengthSum = MaxLL+1; |
| |
| { unsigned ml; |
| for (ml=0; ml<=MaxML; ml++) |
| optPtr->matchLengthFreq[ml] = 1; |
| } |
| optPtr->matchLengthSum = MaxML+1; |
| |
| { unsigned of; |
| for (of=0; of<=MaxOff; of++) |
| optPtr->offCodeFreq[of] = 1; |
| } |
| optPtr->offCodeSum = MaxOff+1; |
| |
| } |
| |
| } else { /* new block : re-use previous statistics, scaled down */ |
| |
| if (compressedLiterals) |
| optPtr->litSum = ZSTD_downscaleStat(optPtr->litFreq, MaxLit, 1); |
| optPtr->litLengthSum = ZSTD_downscaleStat(optPtr->litLengthFreq, MaxLL, 0); |
| optPtr->matchLengthSum = ZSTD_downscaleStat(optPtr->matchLengthFreq, MaxML, 0); |
| optPtr->offCodeSum = ZSTD_downscaleStat(optPtr->offCodeFreq, MaxOff, 0); |
| } |
| |
| 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 = litLength * optPtr->litSumBasePrice; |
| U32 u; |
| for (u=0; u < litLength; u++) { |
| assert(WEIGHT(optPtr->litFreq[literals[u]], optLevel) <= optPtr->litSumBasePrice); /* literal cost should never be negative */ |
| price -= WEIGHT(optPtr->litFreq[literals[u]], optLevel); |
| } |
| return price; |
| } |
| } |
| |
| /* ZSTD_litLengthPrice() : |
| * cost of literalLength symbol */ |
| static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optPtr, int optLevel) |
| { |
| if (optPtr->priceType == zop_predef) return WEIGHT(litLength, 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. |
| * optLevel: when <2, favors small offset for decompression speed (improved cache efficiency) */ |
| FORCE_INLINE_TEMPLATE U32 |
| ZSTD_getMatchPrice(U32 const offset, |
| U32 const matchLength, |
| const optState_t* const optPtr, |
| int const optLevel) |
| { |
| U32 price; |
| U32 const offCode = ZSTD_highbit32(offset+1); |
| U32 const mlBase = matchLength - MINMATCH; |
| assert(matchLength >= MINMATCH); |
| |
| if (optPtr->priceType == zop_predef) /* fixed scheme, do not use statistics */ |
| return WEIGHT(mlBase, optLevel) + ((16 + offCode) * BITCOST_MULTIPLIER); |
| |
| /* 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 + litLengtn <= iend */ |
| static void ZSTD_updateStats(optState_t* const optPtr, |
| U32 litLength, const BYTE* literals, |
| U32 offsetCode, 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++; |
| } |
| |
| /* match offset code (0-2=>repCode; 3+=>offset+2) */ |
| { U32 const offCode = ZSTD_highbit32(offsetCode+1); |
| 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 (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. |
| * ip : assumed <= iend-8 . |
| * @return : nb of positions added */ |
| static U32 ZSTD_insertBt1( |
| ZSTD_matchState_t* ms, |
| const BYTE* const ip, const BYTE* const iend, |
| 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 */ |
| U32 const windowLow = ms->window.lowLimit; |
| 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(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, 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], |
| U32 const ll0, /* tells if associated literal length is 0 or not. This value must be 0 or 1 */ |
| const U32 lengthToBeat, |
| U32 const 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 - ll0; |
| 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 = (curr - matchIndex3) + ZSTD_REP_MOVE; |
| 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 */ |
| } |
| |
| 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 (offCode=%u)", |
| (U32)matchLength, curr - matchIndex, curr - matchIndex + ZSTD_REP_MOVE); |
| assert(matchEndIdx > matchIndex); |
| if (matchLength > matchEndIdx - matchIndex) |
| matchEndIdx = matchIndex + (U32)matchLength; |
| bestLength = matchLength; |
| matches[mnum].off = (curr - matchIndex) + ZSTD_REP_MOVE; |
| 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 (offCode=%u)", |
| (U32)matchLength, curr - matchIndex, curr - matchIndex + ZSTD_REP_MOVE); |
| if (matchLength > matchEndIdx - matchIndex) |
| matchEndIdx = matchIndex + (U32)matchLength; |
| bestLength = matchLength; |
| matches[mnum].off = (curr - matchIndex) + ZSTD_REP_MOVE; |
| 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]; |
| } |
| } |
| } |
| |
| assert(matchEndIdx > curr+8); |
| ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ |
| return mnum; |
| } |
| |
| |
| FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches ( |
| ZSTD_match_t* matches, /* store result (match found, increasing size) in this table */ |
| ZSTD_matchState_t* ms, |
| U32* nextToUpdate3, |
| const BYTE* ip, const BYTE* const iHighLimit, const ZSTD_dictMode_e dictMode, |
| const U32 rep[ZSTD_REP_NUM], |
| U32 const ll0, |
| U32 const lengthToBeat) |
| { |
| const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| U32 const matchLengthSearch = cParams->minMatch; |
| DEBUGLOG(8, "ZSTD_BtGetAllMatches"); |
| if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */ |
| ZSTD_updateTree_internal(ms, ip, iHighLimit, matchLengthSearch, dictMode); |
| switch(matchLengthSearch) |
| { |
| case 3 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 3); |
| default : |
| case 4 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 4); |
| case 5 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 5); |
| case 7 : |
| case 6 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 6); |
| } |
| } |
| |
| /* *********************** |
| * 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, |
| ZSTD_optLdm_t* optLdm, U32 currPosInBlock) { |
| U32 posDiff = currPosInBlock - optLdm->startPosInBlock; |
| /* Note: ZSTD_match_t actually contains offCode and matchLength (before subtracting MINMATCH) */ |
| U32 candidateMatchLength = optLdm->endPosInBlock - optLdm->startPosInBlock - posDiff; |
| U32 candidateOffCode = optLdm->offset + ZSTD_REP_MOVE; |
| |
| /* 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)) { |
| DEBUGLOG(6, "ZSTD_optLdm_maybeAddMatch(): Adding ldm candidate match (offCode: %u matchLength %u) at block position=%u", |
| candidateOffCode, candidateMatchLength, currPosInBlock); |
| matches[*nbMatches].len = candidateMatchLength; |
| matches[*nbMatches].off = candidateOffCode; |
| (*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 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; |
| |
| 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 = ZSTD_BtGetAllMatches(matches, ms, &nextToUpdate3, ip, iend, dictMode, 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<ZSTD_REP_NUM; i++) opt[0].rep[i] = rep[i]; } |
| opt[0].mlen = 0; /* means is_a_literal */ |
| opt[0].litlen = litlen; |
| /* We don't need to include the actual price of the literals because |
| * it is static for the duration of the forward pass, and is included |
| * in every price. We include the literal length to avoid negative |
| * prices when we subtract the previous literal length. |
| */ |
| opt[0].price = ZSTD_litLengthPrice(litlen, optStatePtr, optLevel); |
| |
| /* large match -> immediate encoding */ |
| { U32 const maxML = matches[nbMatches-1].len; |
| U32 const maxOffset = matches[nbMatches-1].off; |
| DEBUGLOG(6, "found %u matches of maxLength=%u and maxOffCode=%u at cPos=%u => start new series", |
| nbMatches, maxML, maxOffset, (U32)(ip-prefixStart)); |
| |
| if (maxML > sufficient_len) { |
| lastSequence.litlen = litlen; |
| lastSequence.mlen = maxML; |
| lastSequence.off = maxOffset; |
| 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 */ |
| { U32 const literalsPrice = 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 offset = matches[matchNb].off; |
| U32 const end = matches[matchNb].len; |
| for ( ; pos <= end ; pos++ ) { |
| U32 const matchPrice = ZSTD_getMatchPrice(offset, pos, optStatePtr, optLevel); |
| U32 const sequencePrice = literalsPrice + matchPrice; |
| DEBUGLOG(7, "rPos:%u => set initial price : %.2f", |
| pos, ZSTD_fCost(sequencePrice)); |
| opt[pos].mlen = pos; |
| opt[pos].off = offset; |
| opt[pos].litlen = litlen; |
| opt[pos].price = 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 |
| + ZSTD_rawLiteralsCost(ip+cur-1, 1, optStatePtr, optLevel) |
| + ZSTD_litLengthPrice(litlen, optStatePtr, optLevel) |
| - 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 newReps = ZSTD_updateRep(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 */ |
| } |
| |
| { U32 const ll0 = (opt[cur].mlen != 0); |
| U32 const litlen = (opt[cur].mlen == 0) ? opt[cur].litlen : 0; |
| U32 const previousPrice = opt[cur].price; |
| U32 const basePrice = previousPrice + ZSTD_litLengthPrice(0, optStatePtr, optLevel); |
| U32 nbMatches = ZSTD_BtGetAllMatches(matches, ms, &nextToUpdate3, inr, iend, dictMode, 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 => offCode=%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 = basePrice + 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 reps = ZSTD_updateRep(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 offCode = 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, offCode, mlen); |
| ZSTD_storeSeq(seqStore, llen, anchor, iend, offCode, mlen-MINMATCH); |
| anchor += advance; |
| ip = anchor; |
| } } |
| ZSTD_setBasePrices(optStatePtr, optLevel); |
| } |
| } /* while (ip < ilimit) */ |
| |
| /* Return the last literals size */ |
| return (size_t)(iend - anchor); |
| } |
| |
| |
| 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_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_noDict); |
| } |
| |
| |
| /* used in 2-pass strategy */ |
| static U32 ZSTD_upscaleStat(unsigned* table, U32 lastEltIndex, int bonus) |
| { |
| U32 s, sum=0; |
| assert(ZSTD_FREQ_DIV+bonus >= 0); |
| for (s=0; s<lastEltIndex+1; s++) { |
| table[s] <<= ZSTD_FREQ_DIV+bonus; |
| table[s]--; |
| sum += table[s]; |
| } |
| return sum; |
| } |
| |
| /* used in 2-pass strategy */ |
| MEM_STATIC void ZSTD_upscaleStats(optState_t* optPtr) |
| { |
| if (ZSTD_compressedLiterals(optPtr)) |
| optPtr->litSum = ZSTD_upscaleStat(optPtr->litFreq, MaxLit, 0); |
| optPtr->litLengthSum = ZSTD_upscaleStat(optPtr->litLengthFreq, MaxLL, 0); |
| optPtr->matchLengthSum = ZSTD_upscaleStat(optPtr->matchLengthFreq, MaxML, 0); |
| optPtr->offCodeSum = ZSTD_upscaleStat(optPtr->offCodeFreq, MaxOff, 0); |
| } |
| |
| /* 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, hence its 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_opt_generic(ms, seqStore, tmpRep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); /* generate stats into ms->opt*/ |
| |
| /* invalidate first scan from history */ |
| ZSTD_resetSeqStore(seqStore); |
| ms->window.base -= srcSize; |
| ms->window.dictLimit += (U32)srcSize; |
| ms->window.lowLimit = ms->window.dictLimit; |
| ms->nextToUpdate = ms->window.dictLimit; |
| |
| /* re-inforce weight of collected statistics */ |
| ZSTD_upscaleStats(&ms->opt); |
| } |
| |
| 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_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, 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-pass strategy: |
| * this strategy makes a first pass over first block to collect statistics |
| * and seed next round's statistics with it. |
| * After 1st pass, function forgets everything, 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) |
| ) { |
| ZSTD_initStats_ultra(ms, seqStore, rep, src, srcSize); |
| } |
| |
| return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, 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_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, 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_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, 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_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, 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_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, 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) */ |
