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- /*
- * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under both the BSD-style license (found in the
- * LICENSE file in the root directory of this source tree) and the GPLv2 (found
- * in the COPYING file in the root directory of this source tree).
- * You may select, at your option, one of the above-listed licenses.
- */
- #include "zstd_compress_internal.h"
- #include "zstd_lazy.h"
- /*-*************************************
- * Binary Tree search
- ***************************************/
- void ZSTD_updateDUBT(
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip, const BYTE* iend,
- U32 mls)
- {
- U32* const hashTable = ms->hashTable;
- U32 const hashLog = cParams->hashLog;
- U32* const bt = ms->chainTable;
- U32 const btLog = cParams->chainLog - 1;
- U32 const btMask = (1 << btLog) - 1;
- const BYTE* const base = ms->window.base;
- U32 const target = (U32)(ip - base);
- U32 idx = ms->nextToUpdate;
- if (idx != target)
- DEBUGLOG(7, "ZSTD_updateDUBT, from %u to %u (dictLimit:%u)",
- idx, target, ms->window.dictLimit);
- assert(ip + 8 <= iend); /* condition for ZSTD_hashPtr */
- (void)iend;
- assert(idx >= ms->window.dictLimit); /* condition for valid base+idx */
- for ( ; idx < target ; idx++) {
- size_t const h = ZSTD_hashPtr(base + idx, hashLog, mls); /* assumption : ip + 8 <= iend */
- U32 const matchIndex = hashTable[h];
- U32* const nextCandidatePtr = bt + 2*(idx&btMask);
- U32* const sortMarkPtr = nextCandidatePtr + 1;
- DEBUGLOG(8, "ZSTD_updateDUBT: insert %u", idx);
- hashTable[h] = idx; /* Update Hash Table */
- *nextCandidatePtr = matchIndex; /* update BT like a chain */
- *sortMarkPtr = ZSTD_DUBT_UNSORTED_MARK;
- }
- ms->nextToUpdate = target;
- }
- /** ZSTD_insertDUBT1() :
- * sort one already inserted but unsorted position
- * assumption : current >= btlow == (current - btmask)
- * doesn't fail */
- static void ZSTD_insertDUBT1(
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- U32 current, const BYTE* inputEnd,
- U32 nbCompares, U32 btLow, int extDict)
- {
- U32* const bt = ms->chainTable;
- U32 const btLog = cParams->chainLog - 1;
- U32 const btMask = (1 << btLog) - 1;
- 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 ip = (current>=dictLimit) ? base + current : dictBase + current;
- const BYTE* const iend = (current>=dictLimit) ? inputEnd : dictBase + dictLimit;
- const BYTE* const dictEnd = dictBase + dictLimit;
- const BYTE* const prefixStart = base + dictLimit;
- const BYTE* match;
- U32* smallerPtr = bt + 2*(current&btMask);
- U32* largerPtr = smallerPtr + 1;
- U32 matchIndex = *smallerPtr;
- U32 dummy32; /* to be nullified at the end */
- U32 const windowLow = ms->window.lowLimit;
- DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)",
- current, dictLimit, windowLow);
- assert(current >= btLow);
- assert(ip < iend); /* condition for ZSTD_count */
- while (nbCompares-- && (matchIndex > windowLow)) {
- U32* const nextPtr = bt + 2*(matchIndex & btMask);
- size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
- assert(matchIndex < current);
- if ( (!extDict)
- || (matchIndex+matchLength >= dictLimit) /* both in current segment*/
- || (current < dictLimit) /* both in extDict */) {
- const BYTE* const mBase = !extDict || ((matchIndex+matchLength) >= dictLimit) ? base : dictBase;
- assert( (matchIndex+matchLength >= dictLimit) /* might be wrong if extDict is incorrectly set to 0 */
- || (current < dictLimit) );
- match = mBase + 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] */
- }
- DEBUGLOG(8, "ZSTD_insertDUBT1: comparing %u with %u : found %u common bytes ",
- current, 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 */
- DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is smaller : next => %u",
- matchIndex, btLow, nextPtr[1]);
- 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 */
- DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is larger => %u",
- matchIndex, btLow, nextPtr[0]);
- largerPtr = nextPtr;
- matchIndex = nextPtr[0];
- } }
- *smallerPtr = *largerPtr = 0;
- }
- static size_t ZSTD_DUBT_findBestMatch (
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* const ip, const BYTE* const iend,
- size_t* offsetPtr,
- U32 const mls,
- U32 const extDict)
- {
- U32* const hashTable = ms->hashTable;
- U32 const hashLog = cParams->hashLog;
- size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
- U32 matchIndex = hashTable[h];
- const BYTE* const base = ms->window.base;
- U32 const current = (U32)(ip-base);
- U32 const windowLow = ms->window.lowLimit;
- U32* const bt = ms->chainTable;
- U32 const btLog = cParams->chainLog - 1;
- U32 const btMask = (1 << btLog) - 1;
- U32 const btLow = (btMask >= current) ? 0 : current - btMask;
- U32 const unsortLimit = MAX(btLow, windowLow);
- U32* nextCandidate = bt + 2*(matchIndex&btMask);
- U32* unsortedMark = bt + 2*(matchIndex&btMask) + 1;
- U32 nbCompares = 1U << cParams->searchLog;
- U32 nbCandidates = nbCompares;
- U32 previousCandidate = 0;
- DEBUGLOG(7, "ZSTD_DUBT_findBestMatch (%u) ", current);
- assert(ip <= iend-8); /* required for h calculation */
- /* reach end of unsorted candidates list */
- while ( (matchIndex > unsortLimit)
- && (*unsortedMark == ZSTD_DUBT_UNSORTED_MARK)
- && (nbCandidates > 1) ) {
- DEBUGLOG(8, "ZSTD_DUBT_findBestMatch: candidate %u is unsorted",
- matchIndex);
- *unsortedMark = previousCandidate;
- previousCandidate = matchIndex;
- matchIndex = *nextCandidate;
- nextCandidate = bt + 2*(matchIndex&btMask);
- unsortedMark = bt + 2*(matchIndex&btMask) + 1;
- nbCandidates --;
- }
- if ( (matchIndex > unsortLimit)
- && (*unsortedMark==ZSTD_DUBT_UNSORTED_MARK) ) {
- DEBUGLOG(7, "ZSTD_DUBT_findBestMatch: nullify last unsorted candidate %u",
- matchIndex);
- *nextCandidate = *unsortedMark = 0; /* nullify next candidate if it's still unsorted (note : simplification, detrimental to compression ratio, beneficial for speed) */
- }
- /* batch sort stacked candidates */
- matchIndex = previousCandidate;
- while (matchIndex) { /* will end on matchIndex == 0 */
- U32* const nextCandidateIdxPtr = bt + 2*(matchIndex&btMask) + 1;
- U32 const nextCandidateIdx = *nextCandidateIdxPtr;
- ZSTD_insertDUBT1(ms, cParams, matchIndex, iend,
- nbCandidates, unsortLimit, extDict);
- matchIndex = nextCandidateIdx;
- nbCandidates++;
- }
- /* find longest match */
- { size_t commonLengthSmaller=0, commonLengthLarger=0;
- 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;
- U32* smallerPtr = bt + 2*(current&btMask);
- U32* largerPtr = bt + 2*(current&btMask) + 1;
- U32 matchEndIdx = current+8+1;
- U32 dummy32; /* to be nullified at the end */
- size_t bestLength = 0;
- matchIndex = hashTable[h];
- hashTable[h] = current; /* Update Hash Table */
- while (nbCompares-- && (matchIndex > windowLow)) {
- U32* const nextPtr = bt + 2*(matchIndex & btMask);
- size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
- const BYTE* match;
- if ((!extDict) || (matchIndex+matchLength >= dictLimit)) {
- 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) {
- if (matchLength > matchEndIdx - matchIndex)
- matchEndIdx = matchIndex + (U32)matchLength;
- if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(current-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) )
- bestLength = matchLength, *offsetPtr = ZSTD_REP_MOVE + current - matchIndex;
- if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */
- break; /* drop, to guarantee consistency (miss a little bit of compression) */
- }
- }
- if (match[matchLength] < ip[matchLength]) {
- /* 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 the search */
- smallerPtr = nextPtr+1; /* new "smaller" => larger of match */
- matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */
- } else {
- /* match is larger than current */
- *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(matchEndIdx > current+8); /* ensure nextToUpdate is increased */
- ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */
- if (bestLength >= MINMATCH) {
- U32 const mIndex = current - ((U32)*offsetPtr - ZSTD_REP_MOVE); (void)mIndex;
- DEBUGLOG(8, "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
- current, (U32)bestLength, (U32)*offsetPtr, mIndex);
- }
- return bestLength;
- }
- }
- /** ZSTD_BtFindBestMatch() : Tree updater, providing best match */
- static size_t ZSTD_BtFindBestMatch (
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* const ip, const BYTE* const iLimit,
- size_t* offsetPtr,
- const U32 mls /* template */)
- {
- DEBUGLOG(7, "ZSTD_BtFindBestMatch");
- if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */
- ZSTD_updateDUBT(ms, cParams, ip, iLimit, mls);
- return ZSTD_DUBT_findBestMatch(ms, cParams, ip, iLimit, offsetPtr, mls, 0);
- }
- static size_t ZSTD_BtFindBestMatch_selectMLS (
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip, const BYTE* const iLimit,
- size_t* offsetPtr)
- {
- switch(cParams->searchLength)
- {
- default : /* includes case 3 */
- case 4 : return ZSTD_BtFindBestMatch(ms, cParams, ip, iLimit, offsetPtr, 4);
- case 5 : return ZSTD_BtFindBestMatch(ms, cParams, ip, iLimit, offsetPtr, 5);
- case 7 :
- case 6 : return ZSTD_BtFindBestMatch(ms, cParams, ip, iLimit, offsetPtr, 6);
- }
- }
- /** Tree updater, providing best match */
- static size_t ZSTD_BtFindBestMatch_extDict (
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* const ip, const BYTE* const iLimit,
- size_t* offsetPtr,
- const U32 mls)
- {
- DEBUGLOG(7, "ZSTD_BtFindBestMatch_extDict");
- if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */
- ZSTD_updateDUBT(ms, cParams, ip, iLimit, mls);
- return ZSTD_DUBT_findBestMatch(ms, cParams, ip, iLimit, offsetPtr, mls, 1);
- }
- static size_t ZSTD_BtFindBestMatch_selectMLS_extDict (
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip, const BYTE* const iLimit,
- size_t* offsetPtr)
- {
- switch(cParams->searchLength)
- {
- default : /* includes case 3 */
- case 4 : return ZSTD_BtFindBestMatch_extDict(ms, cParams, ip, iLimit, offsetPtr, 4);
- case 5 : return ZSTD_BtFindBestMatch_extDict(ms, cParams, ip, iLimit, offsetPtr, 5);
- case 7 :
- case 6 : return ZSTD_BtFindBestMatch_extDict(ms, cParams, ip, iLimit, offsetPtr, 6);
- }
- }
- /* *********************************
- * Hash Chain
- ***********************************/
- #define NEXT_IN_CHAIN(d, mask) chainTable[(d) & mask]
- /* Update chains up to ip (excluded)
- Assumption : always within prefix (i.e. not within extDict) */
- static U32 ZSTD_insertAndFindFirstIndex_internal(
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip, U32 const mls)
- {
- U32* const hashTable = ms->hashTable;
- const U32 hashLog = cParams->hashLog;
- U32* const chainTable = ms->chainTable;
- const U32 chainMask = (1 << cParams->chainLog) - 1;
- const BYTE* const base = ms->window.base;
- const U32 target = (U32)(ip - base);
- U32 idx = ms->nextToUpdate;
- while(idx < target) { /* catch up */
- size_t const h = ZSTD_hashPtr(base+idx, hashLog, mls);
- NEXT_IN_CHAIN(idx, chainMask) = hashTable[h];
- hashTable[h] = idx;
- idx++;
- }
- ms->nextToUpdate = target;
- return hashTable[ZSTD_hashPtr(ip, hashLog, mls)];
- }
- U32 ZSTD_insertAndFindFirstIndex(
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip)
- {
- return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, cParams->searchLength);
- }
- /* inlining is important to hardwire a hot branch (template emulation) */
- FORCE_INLINE_TEMPLATE
- size_t ZSTD_HcFindBestMatch_generic (
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* const ip, const BYTE* const iLimit,
- size_t* offsetPtr,
- const U32 mls, const U32 extDict)
- {
- U32* const chainTable = ms->chainTable;
- const U32 chainSize = (1 << cParams->chainLog);
- const U32 chainMask = chainSize-1;
- const BYTE* const base = ms->window.base;
- const BYTE* const dictBase = ms->window.dictBase;
- const U32 dictLimit = ms->window.dictLimit;
- const BYTE* const prefixStart = base + dictLimit;
- const BYTE* const dictEnd = dictBase + dictLimit;
- const U32 lowLimit = ms->window.lowLimit;
- const U32 current = (U32)(ip-base);
- const U32 minChain = current > chainSize ? current - chainSize : 0;
- U32 nbAttempts = 1U << cParams->searchLog;
- size_t ml=4-1;
- /* HC4 match finder */
- U32 matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls);
- for ( ; (matchIndex>lowLimit) & (nbAttempts>0) ; nbAttempts--) {
- size_t currentMl=0;
- if ((!extDict) || matchIndex >= dictLimit) {
- const BYTE* const match = base + matchIndex;
- if (match[ml] == ip[ml]) /* potentially better */
- currentMl = ZSTD_count(ip, match, iLimit);
- } else {
- const BYTE* const match = dictBase + matchIndex;
- assert(match+4 <= dictEnd);
- if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
- currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4;
- }
- /* save best solution */
- if (currentMl > ml) {
- ml = currentMl;
- *offsetPtr = current - matchIndex + ZSTD_REP_MOVE;
- if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
- }
- if (matchIndex <= minChain) break;
- matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
- }
- return ml;
- }
- FORCE_INLINE_TEMPLATE size_t ZSTD_HcFindBestMatch_selectMLS (
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip, const BYTE* const iLimit,
- size_t* offsetPtr)
- {
- switch(cParams->searchLength)
- {
- default : /* includes case 3 */
- case 4 : return ZSTD_HcFindBestMatch_generic(ms, cParams, ip, iLimit, offsetPtr, 4, 0);
- case 5 : return ZSTD_HcFindBestMatch_generic(ms, cParams, ip, iLimit, offsetPtr, 5, 0);
- case 7 :
- case 6 : return ZSTD_HcFindBestMatch_generic(ms, cParams, ip, iLimit, offsetPtr, 6, 0);
- }
- }
- FORCE_INLINE_TEMPLATE size_t ZSTD_HcFindBestMatch_extDict_selectMLS (
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip, const BYTE* const iLimit,
- size_t* const offsetPtr)
- {
- switch(cParams->searchLength)
- {
- default : /* includes case 3 */
- case 4 : return ZSTD_HcFindBestMatch_generic(ms, cParams, ip, iLimit, offsetPtr, 4, 1);
- case 5 : return ZSTD_HcFindBestMatch_generic(ms, cParams, ip, iLimit, offsetPtr, 5, 1);
- case 7 :
- case 6 : return ZSTD_HcFindBestMatch_generic(ms, cParams, ip, iLimit, offsetPtr, 6, 1);
- }
- }
- /* *******************************
- * Common parser - lazy strategy
- *********************************/
- FORCE_INLINE_TEMPLATE
- size_t ZSTD_compressBlock_lazy_generic(
- ZSTD_matchState_t* ms, seqStore_t* seqStore,
- U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams,
- const void* src, size_t srcSize,
- const U32 searchMethod, const U32 depth)
- {
- 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 + ms->window.dictLimit;
- typedef size_t (*searchMax_f)(
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip, const BYTE* iLimit, size_t* offsetPtr);
- searchMax_f const searchMax = searchMethod ? ZSTD_BtFindBestMatch_selectMLS : ZSTD_HcFindBestMatch_selectMLS;
- U32 offset_1 = rep[0], offset_2 = rep[1], savedOffset=0;
- /* init */
- ip += (ip==base);
- ms->nextToUpdate3 = ms->nextToUpdate;
- { U32 const maxRep = (U32)(ip-base);
- if (offset_2 > maxRep) savedOffset = offset_2, offset_2 = 0;
- if (offset_1 > maxRep) savedOffset = offset_1, offset_1 = 0;
- }
- /* Match Loop */
- while (ip < ilimit) {
- size_t matchLength=0;
- size_t offset=0;
- const BYTE* start=ip+1;
- /* check repCode */
- if ((offset_1>0) & (MEM_read32(ip+1) == MEM_read32(ip+1 - offset_1))) {
- /* repcode : we take it */
- matchLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
- if (depth==0) goto _storeSequence;
- }
- /* first search (depth 0) */
- { size_t offsetFound = 99999999;
- size_t const ml2 = searchMax(ms, cParams, ip, iend, &offsetFound);
- if (ml2 > matchLength)
- matchLength = ml2, start = ip, offset=offsetFound;
- }
- if (matchLength < 4) {
- ip += ((ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */
- continue;
- }
- /* let's try to find a better solution */
- if (depth>=1)
- while (ip<ilimit) {
- ip ++;
- if ((offset) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
- size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4;
- int const gain2 = (int)(mlRep * 3);
- int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offset+1) + 1);
- if ((mlRep >= 4) && (gain2 > gain1))
- matchLength = mlRep, offset = 0, start = ip;
- }
- { size_t offset2=99999999;
- size_t const ml2 = searchMax(ms, cParams, ip, iend, &offset2);
- int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1)); /* raw approx */
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 4);
- if ((ml2 >= 4) && (gain2 > gain1)) {
- matchLength = ml2, offset = offset2, start = ip;
- continue; /* search a better one */
- } }
- /* let's find an even better one */
- if ((depth==2) && (ip<ilimit)) {
- ip ++;
- if ((offset) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
- size_t const ml2 = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4;
- int const gain2 = (int)(ml2 * 4);
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 1);
- if ((ml2 >= 4) && (gain2 > gain1))
- matchLength = ml2, offset = 0, start = ip;
- }
- { size_t offset2=99999999;
- size_t const ml2 = searchMax(ms, cParams, ip, iend, &offset2);
- int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1)); /* raw approx */
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 7);
- if ((ml2 >= 4) && (gain2 > gain1)) {
- matchLength = ml2, offset = offset2, start = ip;
- continue;
- } } }
- break; /* nothing found : store previous solution */
- }
- /* NOTE:
- * start[-offset+ZSTD_REP_MOVE-1] is undefined behavior.
- * (-offset+ZSTD_REP_MOVE-1) is unsigned, and is added to start, which
- * overflows the pointer, which is undefined behavior.
- */
- /* catch up */
- if (offset) {
- while ( ((start > anchor) & (start - (offset-ZSTD_REP_MOVE) > base))
- && (start[-1] == (start-(offset-ZSTD_REP_MOVE))[-1]) ) /* only search for offset within prefix */
- { start--; matchLength++; }
- offset_2 = offset_1; offset_1 = (U32)(offset - ZSTD_REP_MOVE);
- }
- /* store sequence */
- _storeSequence:
- { size_t const litLength = start - anchor;
- ZSTD_storeSeq(seqStore, litLength, anchor, (U32)offset, matchLength-MINMATCH);
- anchor = ip = start + matchLength;
- }
- /* check immediate repcode */
- while ( ((ip <= ilimit) & (offset_2>0))
- && (MEM_read32(ip) == MEM_read32(ip - offset_2)) ) {
- /* store sequence */
- matchLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
- offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset; /* swap repcodes */
- ZSTD_storeSeq(seqStore, 0, anchor, 0, matchLength-MINMATCH);
- ip += matchLength;
- anchor = ip;
- continue; /* faster when present ... (?) */
- } }
- /* Save reps for next block */
- rep[0] = offset_1 ? offset_1 : savedOffset;
- rep[1] = offset_2 ? offset_2 : savedOffset;
- /* Return the last literals size */
- return iend - anchor;
- }
- size_t ZSTD_compressBlock_btlazy2(
- ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
- {
- return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, cParams, src, srcSize, 1, 2);
- }
- size_t ZSTD_compressBlock_lazy2(
- ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
- {
- return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, cParams, src, srcSize, 0, 2);
- }
- size_t ZSTD_compressBlock_lazy(
- ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
- {
- return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, cParams, src, srcSize, 0, 1);
- }
- size_t ZSTD_compressBlock_greedy(
- ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
- {
- return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, cParams, src, srcSize, 0, 0);
- }
- FORCE_INLINE_TEMPLATE
- size_t ZSTD_compressBlock_lazy_extDict_generic(
- ZSTD_matchState_t* ms, seqStore_t* seqStore,
- U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams,
- const void* src, size_t srcSize,
- const U32 searchMethod, const U32 depth)
- {
- 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 U32 dictLimit = ms->window.dictLimit;
- const U32 lowestIndex = ms->window.lowLimit;
- const BYTE* const prefixStart = base + dictLimit;
- const BYTE* const dictBase = ms->window.dictBase;
- const BYTE* const dictEnd = dictBase + dictLimit;
- const BYTE* const dictStart = dictBase + lowestIndex;
- typedef size_t (*searchMax_f)(
- ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
- const BYTE* ip, const BYTE* iLimit, size_t* offsetPtr);
- searchMax_f searchMax = searchMethod ? ZSTD_BtFindBestMatch_selectMLS_extDict : ZSTD_HcFindBestMatch_extDict_selectMLS;
- U32 offset_1 = rep[0], offset_2 = rep[1];
- /* init */
- ms->nextToUpdate3 = ms->nextToUpdate;
- ip += (ip == prefixStart);
- /* Match Loop */
- while (ip < ilimit) {
- size_t matchLength=0;
- size_t offset=0;
- const BYTE* start=ip+1;
- U32 current = (U32)(ip-base);
- /* check repCode */
- { const U32 repIndex = (U32)(current+1 - offset_1);
- const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
- const BYTE* const repMatch = repBase + repIndex;
- if (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex > lowestIndex)) /* intentional overflow */
- if (MEM_read32(ip+1) == MEM_read32(repMatch)) {
- /* repcode detected we should take it */
- const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
- matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repEnd, prefixStart) + 4;
- if (depth==0) goto _storeSequence;
- } }
- /* first search (depth 0) */
- { size_t offsetFound = 99999999;
- size_t const ml2 = searchMax(ms, cParams, ip, iend, &offsetFound);
- if (ml2 > matchLength)
- matchLength = ml2, start = ip, offset=offsetFound;
- }
- if (matchLength < 4) {
- ip += ((ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */
- continue;
- }
- /* let's try to find a better solution */
- if (depth>=1)
- while (ip<ilimit) {
- ip ++;
- current++;
- /* check repCode */
- if (offset) {
- const U32 repIndex = (U32)(current - offset_1);
- const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
- const BYTE* const repMatch = repBase + repIndex;
- if (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex > lowestIndex)) /* intentional overflow */
- if (MEM_read32(ip) == MEM_read32(repMatch)) {
- /* repcode detected */
- const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
- size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
- int const gain2 = (int)(repLength * 3);
- int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offset+1) + 1);
- if ((repLength >= 4) && (gain2 > gain1))
- matchLength = repLength, offset = 0, start = ip;
- } }
- /* search match, depth 1 */
- { size_t offset2=99999999;
- size_t const ml2 = searchMax(ms, cParams, ip, iend, &offset2);
- int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1)); /* raw approx */
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 4);
- if ((ml2 >= 4) && (gain2 > gain1)) {
- matchLength = ml2, offset = offset2, start = ip;
- continue; /* search a better one */
- } }
- /* let's find an even better one */
- if ((depth==2) && (ip<ilimit)) {
- ip ++;
- current++;
- /* check repCode */
- if (offset) {
- const U32 repIndex = (U32)(current - offset_1);
- const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
- const BYTE* const repMatch = repBase + repIndex;
- if (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex > lowestIndex)) /* intentional overflow */
- if (MEM_read32(ip) == MEM_read32(repMatch)) {
- /* repcode detected */
- const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
- size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
- int const gain2 = (int)(repLength * 4);
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 1);
- if ((repLength >= 4) && (gain2 > gain1))
- matchLength = repLength, offset = 0, start = ip;
- } }
- /* search match, depth 2 */
- { size_t offset2=99999999;
- size_t const ml2 = searchMax(ms, cParams, ip, iend, &offset2);
- int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1)); /* raw approx */
- int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 7);
- if ((ml2 >= 4) && (gain2 > gain1)) {
- matchLength = ml2, offset = offset2, start = ip;
- continue;
- } } }
- break; /* nothing found : store previous solution */
- }
- /* catch up */
- if (offset) {
- U32 const matchIndex = (U32)((start-base) - (offset - ZSTD_REP_MOVE));
- const BYTE* match = (matchIndex < dictLimit) ? dictBase + matchIndex : base + matchIndex;
- const BYTE* const mStart = (matchIndex < dictLimit) ? dictStart : prefixStart;
- while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */
- offset_2 = offset_1; offset_1 = (U32)(offset - ZSTD_REP_MOVE);
- }
- /* store sequence */
- _storeSequence:
- { size_t const litLength = start - anchor;
- ZSTD_storeSeq(seqStore, litLength, anchor, (U32)offset, matchLength-MINMATCH);
- anchor = ip = start + matchLength;
- }
- /* check immediate repcode */
- while (ip <= ilimit) {
- const U32 repIndex = (U32)((ip-base) - offset_2);
- const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
- const BYTE* const repMatch = repBase + repIndex;
- if (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex > lowestIndex)) /* intentional overflow */
- if (MEM_read32(ip) == MEM_read32(repMatch)) {
- /* repcode detected we should take it */
- const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
- matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
- offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset; /* swap offset history */
- ZSTD_storeSeq(seqStore, 0, anchor, 0, matchLength-MINMATCH);
- ip += matchLength;
- anchor = ip;
- continue; /* faster when present ... (?) */
- }
- break;
- } }
- /* Save reps for next block */
- rep[0] = offset_1;
- rep[1] = offset_2;
- /* Return the last literals size */
- return iend - anchor;
- }
- size_t ZSTD_compressBlock_greedy_extDict(
- ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
- {
- return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, cParams, src, srcSize, 0, 0);
- }
- size_t ZSTD_compressBlock_lazy_extDict(
- ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
- {
- return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, cParams, src, srcSize, 0, 1);
- }
- size_t ZSTD_compressBlock_lazy2_extDict(
- ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
- {
- return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, cParams, src, srcSize, 0, 2);
- }
- size_t ZSTD_compressBlock_btlazy2_extDict(
- ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
- ZSTD_compressionParameters const* cParams, void const* src, size_t srcSize)
- {
- return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, cParams, src, srcSize, 1, 2);
- }
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