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Fix Off-By-One Error in Counting DDS Search Attempts

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This caused us to double-search the first position and fail to search the
last position in the chain, slowing down search and making it less effective.
This commit is contained in:
W. Felix Handte
2020-09-10 18:51:52 -04:00
parent d46306087b
commit df386b3d8d
1 changed files with 2 additions and 2 deletions
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lib/compress/zstd_lazy.c
+2 -2
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@@ -575,7 +575,7 @@ size_t ZSTD_HcFindBestMatch_generic (
const U32 ddsMinChain = ddsSize > ddsChainSize ? ddsSize - ddsChainSize : 0; const U32 ddsMinChain = ddsSize > ddsChainSize ? ddsSize - ddsChainSize : 0;
const U32 bucketSize = (1 << DD_BLOG); const U32 bucketSize = (1 << DD_BLOG);
U32 attemptNb = 0; U32 attemptNb = 1;
matchIndex = dms->hashTable[ddsIdx]; matchIndex = dms->hashTable[ddsIdx];
@@ -603,7 +603,7 @@ size_t ZSTD_HcFindBestMatch_generic (
break; break;
} }
if (attemptNb < bucketSize - 1) { if (attemptNb < bucketSize) {
matchIndex = dms->hashTable[ddsIdx + attemptNb]; matchIndex = dms->hashTable[ddsIdx + attemptNb];
} else { } else {
matchIndex = dms->chainTable[matchIndex & ddsChainMask]; matchIndex = dms->chainTable[matchIndex & ddsChainMask];