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| author | Yann Collet <yann.collet.73@gmail.com> | 2015-03-30 14:57:26 (GMT) |
|---|---|---|
| committer | Yann Collet <yann.collet.73@gmail.com> | 2015-03-30 14:57:26 (GMT) |
| commit | 002ec60f0feadc07a25a6f18a7b2b4ace3c1b718 (patch) | |
| tree | 375783b9749a597dbd15853ec841ff22316a40de | |
| parent | 8cb06d5b9922b16854b05081ce829c223a8129fd (diff) | |
| download | lz4-002ec60f0feadc07a25a6f18a7b2b4ace3c1b718.zip lz4-002ec60f0feadc07a25a6f18a7b2b4ace3c1b718.tar.gz lz4-002ec60f0feadc07a25a6f18a7b2b4ace3c1b718.tar.bz2 | |
restored lz4hc compression ratio
| -rw-r--r-- | lib/lz4hc.c | 44 |
1 files changed, 24 insertions, 20 deletions
diff --git a/lib/lz4hc.c b/lib/lz4hc.c index a03c511..c7a94a0 100644 --- a/lib/lz4hc.c +++ b/lib/lz4hc.c @@ -37,7 +37,7 @@ You can contact the author at : /************************************** Tuning Parameter **************************************/ -static const int LZ4HC_compressionLevel_default = 8; +static const int LZ4HC_compressionLevel_default = 9; /************************************** @@ -206,9 +206,9 @@ FORCE_INLINE int LZ4HC_InsertAndFindBestMatch (LZ4HC_Data_Structure* hc4, /* I FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch ( LZ4HC_Data_Structure* hc4, - const BYTE* ip, - const BYTE* iLowLimit, - const BYTE* iHighLimit, + const BYTE* const ip, + const BYTE* const iLowLimit, + const BYTE* const iHighLimit, int longest, const BYTE** matchpos, const BYTE** startpos, @@ -218,9 +218,9 @@ FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch ( U32* const HashTable = hc4->hashTable; const BYTE* const base = hc4->base; const U32 dictLimit = hc4->dictLimit; + const BYTE* const lowPrefixPtr = base + dictLimit; const U32 lowLimit = (hc4->lowLimit + 64 KB > (U32)(ip-base)) ? hc4->lowLimit : (U32)(ip - base) - (64 KB - 1); const BYTE* const dictBase = hc4->dictBase; - const BYTE* match; U32 matchIndex; int nbAttempts = maxNbAttempts; int delta = (int)(ip-iLowLimit); @@ -235,37 +235,41 @@ FORCE_INLINE int LZ4HC_InsertAndGetWiderMatch ( nbAttempts--; if (matchIndex >= dictLimit) { - match = base + matchIndex; - if (*(iLowLimit + longest) == *(match - delta + longest)) - if (LZ4_read32(match) == LZ4_read32(ip)) + const BYTE* matchPtr = base + matchIndex; + if (*(iLowLimit + longest) == *(matchPtr - delta + longest)) + if (LZ4_read32(matchPtr) == LZ4_read32(ip)) { - const BYTE* startt = ip; - const BYTE* tmpMatch = match; - const BYTE* const matchEnd = ip + MINMATCH + LZ4_count(ip+MINMATCH, match+MINMATCH, iHighLimit); + int mlt = MINMATCH + LZ4_count(ip+MINMATCH, matchPtr+MINMATCH, iHighLimit); + int back = 0; + + while ((ip+back>iLowLimit) + && (matchPtr+back > lowPrefixPtr) + && (ip[back-1] == matchPtr[back-1])) + back--; - while ((startt>iLowLimit) && (tmpMatch > iLowLimit) && (startt[-1] == tmpMatch[-1])) {startt--; tmpMatch--;} + mlt -= back; - if ((matchEnd-startt) > longest) + if (mlt > longest) { - longest = (int)(matchEnd-startt); - *matchpos = tmpMatch; - *startpos = startt; + longest = (int)mlt; + *matchpos = matchPtr+back; + *startpos = ip+back; } } } else { - match = dictBase + matchIndex; - if (LZ4_read32(match) == LZ4_read32(ip)) + const BYTE* matchPtr = dictBase + matchIndex; + if (LZ4_read32(matchPtr) == LZ4_read32(ip)) { size_t mlt; int back=0; const BYTE* vLimit = ip + (dictLimit - matchIndex); if (vLimit > iHighLimit) vLimit = iHighLimit; - mlt = LZ4_count(ip+MINMATCH, match+MINMATCH, vLimit) + MINMATCH; + mlt = LZ4_count(ip+MINMATCH, matchPtr+MINMATCH, vLimit) + MINMATCH; if ((ip+mlt == vLimit) && (vLimit < iHighLimit)) mlt += LZ4_count(ip+mlt, base+dictLimit, iHighLimit); - while ((ip+back > iLowLimit) && (matchIndex+back > lowLimit) && (ip[back-1] == match[back-1])) back--; + while ((ip+back > iLowLimit) && (matchIndex+back > lowLimit) && (ip[back-1] == matchPtr[back-1])) back--; mlt -= back; if ((int)mlt > longest) { longest = (int)mlt; *matchpos = base + matchIndex + back; *startpos = ip+back; } } |