diff options
| -rw-r--r-- | lib/lz4hc.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/lib/lz4hc.c b/lib/lz4hc.c index b8ff72a..4122af4 100644 --- a/lib/lz4hc.c +++ b/lib/lz4hc.c @@ -158,9 +158,11 @@ int LZ4HC_countBack(const BYTE* const ip, const BYTE* const match, #endif -static U32 LZ4HC_rotatePattern(size_t const length, U32 const pattern) +static U32 LZ4HC_rotatePattern(size_t const rotate, U32 const pattern) { - size_t const bitsToRotate = (length & (sizeof(pattern) - 1)) << 3; + size_t const bitsToRotate = (rotate & (sizeof(pattern) - 1)) << 3; + if (bitsToRotate == 0) + return pattern; return LZ4HC_rotl32(pattern, (int)bitsToRotate); } @@ -338,9 +340,15 @@ LZ4HC_InsertAndGetWiderMatch ( forwardPatternLength += LZ4HC_countPattern(lowPrefixPtr, iHighLimit, rotatedPattern); } { const BYTE* const lowestMatchPtr = extDict ? dictStart : lowPrefixPtr; - size_t const backLengthRaw = LZ4HC_reverseCountPattern(matchPtr, lowestMatchPtr, pattern); - size_t const backLength = matchCandidateIdx - MAX(matchCandidateIdx - (U32)backLengthRaw, lowestMatchIndex); - size_t const currentSegmentLength = backLength + forwardPatternLength; + size_t backLength = LZ4HC_reverseCountPattern(matchPtr, lowestMatchPtr, pattern); + size_t currentSegmentLength; + if (!extDict && matchPtr - backLength == lowPrefixPtr && hc4->lowLimit < dictLimit) { + U32 const rotatedPattern = LZ4HC_rotatePattern((U32)(-(int)backLength), pattern); + backLength += LZ4HC_reverseCountPattern(dictBase + dictLimit, dictStart, rotatedPattern); + } + /* Limit backLength not go further than lowestMatchIndex */ + backLength = matchCandidateIdx - MAX(matchCandidateIdx - (U32)backLength, lowestMatchIndex); + currentSegmentLength = backLength + forwardPatternLength; if ( (currentSegmentLength >= srcPatternLength) /* current pattern segment large enough to contain full srcPatternLength */ && (forwardPatternLength <= srcPatternLength) ) { /* haven't reached this position yet */ |