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Check Dict Match State in ZSTD_HcFindBestMatch_generic

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This commit is contained in:
W. Felix Handte 2018-05-29 16:26:23 -04:00
parent 211a61b69b
commit 6204b6d592
1 changed files with 31 additions and 0 deletions
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31
lib/compress/zstd_lazy.c
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@ -424,6 +424,37 @@ size_t ZSTD_HcFindBestMatch_generic (
matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
}
if (dictMode == ZSTD_dictMatchState) {
const ZSTD_matchState_t* const dms = ms->dictMatchState;
const U32* const dmsChainTable = dms->chainTable;
const U32 dmsLowestIndex = dms->window.dictLimit;
const BYTE* const dmsBase = dms->window.base;
const BYTE* const dmsEnd = dms->window.nextSrc;
const U32 dmsSize = (U32)(dmsEnd - dmsBase);
const U32 dmsIndexDelta = dictLimit - dmsSize;
const U32 dmsMinChain = dmsSize > chainSize ? dmsSize - chainSize : 0;
matchIndex = dms->hashTable[ZSTD_hashPtr(ip, cParams->hashLog, mls)];
for ( ; (matchIndex>dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--) {
size_t currentMl=0;
const BYTE* const match = dmsBase + matchIndex;
assert(match+4 <= dmsEnd);
if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4;
/* save best solution */
if (currentMl > ml) {
ml = currentMl;
*offsetPtr = current - (matchIndex + dmsIndexDelta) + ZSTD_REP_MOVE;
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
}
if (matchIndex <= dmsMinChain) break;
matchIndex = dmsChainTable[matchIndex & chainMask];
}
}
return ml;
}