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small hc speed improvement

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This commit is contained in:
Yann Collet 2015-11-22 13:24:05 +01:00
parent 428619ccd7
commit 287b7d9607
1 changed files with 67 additions and 7 deletions
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74
lib/zstd_compress.c
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@ -1206,6 +1206,66 @@ size_t ZSTD_HcFindBestMatch (
const BYTE* const ip, const BYTE* const iLimit, const BYTE* const ip, const BYTE* const iLimit,
size_t* offsetPtr, size_t* offsetPtr,
const U32 maxNbAttempts, const U32 matchLengthSearch) const U32 maxNbAttempts, const U32 matchLengthSearch)
{
const BYTE* const base = zc->base;
const U32 current = (U32)(ip-base);
U32* const chainTable = zc->contentTable;
const U32 chainSize = (1 << zc->params.contentLog);
const U32 minChain = current > chainSize ? current - chainSize : 0;
const U32 chainMask = chainSize-1;
const U32 lowLimit = zc->lowLimit;
U32 matchIndex;
const BYTE* match;
int nbAttempts=maxNbAttempts;
size_t ml=0;
/* HC4 match finder */
matchIndex = ZSTD_insertAndFindFirstIndex (zc, ip, matchLengthSearch);
while ((matchIndex>lowLimit) && (nbAttempts))
{
nbAttempts--;
match = base + matchIndex;
if (match[ml] == ip[ml]) /* potentially better */
{
const size_t mlt = ZSTD_count(ip, match, iLimit);
if (mlt > ml)
//if (((int)(4*mlt) - (int)ZSTD_highbit((U32)(ip-match)+1)) > ((int)(4*ml) - (int)ZSTD_highbit((U32)((*offsetPtr)+1))))
{
ml = mlt; *offsetPtr = ip-match;
if (ip+mlt >= iLimit) break;
}
}
if (matchIndex <= minChain) break;
matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
}
return ml;
}
FORCE_INLINE size_t ZSTD_HcFindBestMatch_selectMLS (
ZSTD_CCtx* zc, /* Index table will be updated */
const BYTE* ip, const BYTE* const iLimit,
size_t* offsetPtr,
const U32 maxNbAttempts, const U32 matchLengthSearch)
{
switch(matchLengthSearch)
{
default :
case 4 : return ZSTD_HcFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4);
case 5 : return ZSTD_HcFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5);
case 6 : return ZSTD_HcFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6);
}
}
FORCE_INLINE /* inlining is important to hardwire a hot branch (template emulation) */
size_t ZSTD_HcFindBestMatch_extDict (
ZSTD_CCtx* zc, /* Index table will be updated */
const BYTE* const ip, const BYTE* const iLimit,
size_t* offsetPtr,
const U32 maxNbAttempts, const U32 matchLengthSearch)
{ {
U32* const chainTable = zc->contentTable; U32* const chainTable = zc->contentTable;
const U32 chainSize = (1 << zc->params.contentLog); const U32 chainSize = (1 << zc->params.contentLog);
@ -1264,7 +1324,7 @@ size_t ZSTD_HcFindBestMatch (
} }
FORCE_INLINE size_t ZSTD_HcFindBestMatch_selectMLS ( FORCE_INLINE size_t ZSTD_HcFindBestMatch_extDict_selectMLS (
ZSTD_CCtx* zc, /* Index table will be updated */ ZSTD_CCtx* zc, /* Index table will be updated */
const BYTE* ip, const BYTE* const iLimit, const BYTE* ip, const BYTE* const iLimit,
size_t* offsetPtr, size_t* offsetPtr,
@ -1273,16 +1333,16 @@ FORCE_INLINE size_t ZSTD_HcFindBestMatch_selectMLS (
switch(matchLengthSearch) switch(matchLengthSearch)
{ {
default : default :
case 4 : return ZSTD_HcFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4); case 4 : return ZSTD_HcFindBestMatch_extDict(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4);
case 5 : return ZSTD_HcFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5); case 5 : return ZSTD_HcFindBestMatch_extDict(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5);
case 6 : return ZSTD_HcFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6); case 6 : return ZSTD_HcFindBestMatch_extDict(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6);
} }
} }
/* ****************************** /* *******************************
* Common parser - lazy strategy * Common parser - lazy strategy
********************************/ *********************************/
FORCE_INLINE FORCE_INLINE
size_t ZSTD_compressBlock_lazy_generic(ZSTD_CCtx* ctx, size_t ZSTD_compressBlock_lazy_generic(ZSTD_CCtx* ctx,
void* dst, size_t maxDstSize, const void* src, size_t srcSize, void* dst, size_t maxDstSize, const void* src, size_t srcSize,
@ -1478,7 +1538,7 @@ size_t ZSTD_compressBlock_lazy_extDict_generic(ZSTD_CCtx* ctx,
typedef size_t (*searchMax_f)(ZSTD_CCtx* zc, const BYTE* ip, const BYTE* iLimit, typedef size_t (*searchMax_f)(ZSTD_CCtx* zc, const BYTE* ip, const BYTE* iLimit,
size_t* offsetPtr, size_t* offsetPtr,
U32 maxNbAttempts, U32 matchLengthSearch); U32 maxNbAttempts, U32 matchLengthSearch);
searchMax_f searchMax = searchMethod ? ZSTD_BtFindBestMatch_selectMLS : ZSTD_HcFindBestMatch_selectMLS; searchMax_f searchMax = searchMethod ? ZSTD_BtFindBestMatch_selectMLS : ZSTD_HcFindBestMatch_extDict_selectMLS;
/* init */ /* init */
ZSTD_resetSeqStore(seqStorePtr); ZSTD_resetSeqStore(seqStorePtr);