diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/lz4hc.c | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/lib/lz4hc.c b/lib/lz4hc.c index 1b3596f..059c4b5 100644 --- a/lib/lz4hc.c +++ b/lib/lz4hc.c @@ -291,15 +291,12 @@ LZ4HC_InsertAndGetWiderMatch ( if (candidateDist > distanceToNextMatch) { distanceToNextMatch = candidateDist; matchChainPos = pos; - } - } + } } if (distanceToNextMatch > 1) { if (distanceToNextMatch > matchIndex) break; /* avoid overflow */ matchIndex -= distanceToNextMatch; continue; - } - } - } + } } } { U32 const distNextMatch = DELTANEXTU16(chainTable, matchIndex); if (patternAnalysis && distNextMatch==1 && matchChainPos==0) { @@ -309,7 +306,7 @@ LZ4HC_InsertAndGetWiderMatch ( if ( ((pattern & 0xFFFF) == (pattern >> 16)) & ((pattern & 0xFF) == (pattern >> 24)) ) { repeat = rep_confirmed; - srcPatternLength = LZ4HC_countPattern(ip+4, iHighLimit, pattern) + 4; + srcPatternLength = LZ4HC_countPattern(ip+sizeof(pattern), iHighLimit, pattern) + sizeof(pattern); } else { repeat = rep_not; } } @@ -318,19 +315,29 @@ LZ4HC_InsertAndGetWiderMatch ( const BYTE* const matchPtr = base + matchCandidateIdx; if (LZ4_read32(matchPtr) == pattern) { /* good candidate */ size_t const forwardPatternLength = LZ4HC_countPattern(matchPtr+sizeof(pattern), iHighLimit, pattern) + sizeof(pattern); - const BYTE* const maxLowPtr = (lowPrefixPtr + MAX_DISTANCE >= ip) ? lowPrefixPtr : ip - MAX_DISTANCE; - size_t const backLength = LZ4HC_reverseCountPattern(matchPtr, maxLowPtr, pattern); + const BYTE* const lowestMatchPtr = (lowPrefixPtr + MAX_DISTANCE >= ip) ? lowPrefixPtr : ip - MAX_DISTANCE; + size_t const backLength = LZ4HC_reverseCountPattern(matchPtr, lowestMatchPtr, pattern); size_t const currentSegmentLength = backLength + forwardPatternLength; if ( (currentSegmentLength >= srcPatternLength) /* current pattern segment large enough to contain full srcPatternLength */ && (forwardPatternLength <= srcPatternLength) ) { /* haven't reached this position yet */ matchIndex = matchCandidateIdx + (U32)forwardPatternLength - (U32)srcPatternLength; /* best position, full pattern, might be followed by more match */ } else { - matchIndex = matchCandidateIdx - (U32)backLength; /* let's go to farthest segment position, will find a match of length currentSegmentLength + maybe some back */ - } + matchIndex = matchCandidateIdx - (U32)backLength; /* farthest position in current segment, will find a match of length currentSegmentLength + maybe some back */ + if (lookBackLength==0) { /* no back possible */ + size_t const maxML = MIN(currentSegmentLength, srcPatternLength); + if ((size_t)longest < maxML) { + longest = maxML; + *matchpos = base + matchIndex; /* virtual pos, relative to ip, to retrieve offset */ + *startpos = ip; + } + { U32 const distToNextPattern = DELTANEXTU16(chainTable, matchIndex); + if (distToNextPattern > matchIndex) break; /* avoid overflow */ + matchIndex -= distToNextPattern; + } } } continue; } } - } } + } } /* PA optimization */ /* follow current chain */ matchIndex -= DELTANEXTU16(chainTable, matchIndex+matchChainPos); |