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ZSTD_fast: Don't Search Dict Context When Mismatch Was Found

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This commit is contained in:
W. Felix Handte
2018-09-14 15:23:35 -07:00
parent b287b8f7c6
commit b048af5999
1 changed files with 6 additions and 2 deletions
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lib/compress/zstd_fast.c
+6 -2
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@@ -124,8 +124,7 @@ size_t ZSTD_compressBlock_fast_generic(
mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4; mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
ip++; ip++;
ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH); ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);
} else if ( (matchIndex <= prefixStartIndex) } else if ( (matchIndex <= prefixStartIndex) ) {
|| (MEM_read32(match) != MEM_read32(ip)) ) {
if (dictMode == ZSTD_dictMatchState) { if (dictMode == ZSTD_dictMatchState) {
U32 const dictMatchIndex = dictHashTable[h]; U32 const dictMatchIndex = dictHashTable[h];
const BYTE* dictMatch = dictBase + dictMatchIndex; const BYTE* dictMatch = dictBase + dictMatchIndex;
@@ -151,6 +150,11 @@ size_t ZSTD_compressBlock_fast_generic(
ip += ((ip-anchor) >> kSearchStrength) + stepSize; ip += ((ip-anchor) >> kSearchStrength) + stepSize;
continue; continue;
} }
} else if (MEM_read32(match) != MEM_read32(ip)) {
/* it's not a match, and we're not going to check the dictionary */
assert(stepSize >= 1);
ip += ((ip-anchor) >> kSearchStrength) + stepSize;
continue;
} else { } else {
/* found a regular match */ /* found a regular match */
U32 const offset = (U32)(ip-match); U32 const offset = (U32)(ip-match);