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First Repcode Check

dev
W. Felix Handte 2018-05-23 15:06:24 -04:00
parent f74c2cd673
commit a2a24bebec
1 changed files with 24 additions and 1 deletions
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25
lib/compress/zstd_lazy.c
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@ -493,7 +493,9 @@ size_t ZSTD_compressBlock_lazy_generic(
const BYTE* anchor = istart;
const BYTE* const iend = istart + srcSize;
const BYTE* const ilimit = iend - 8;
const BYTE* const prefixLowest = ms->window.base + ms->window.dictLimit;
const BYTE* const base = ms->window.base;
const U32 prefixLowestIndex = ms->window.dictLimit;
const BYTE* const prefixLowest = base + prefixLowestIndex;
typedef size_t (*searchMax_f)(
ZSTD_matchState_t* ms, ZSTD_compressionParameters const* cParams,
@ -512,6 +514,9 @@ size_t ZSTD_compressBlock_lazy_generic(
dictBase + dictLowestIndex : NULL;
const BYTE* const dictEnd = dictMode == ZSTD_dictMatchState ?
dms->window.nextSrc : NULL;
const U32 dictIndexDelta = dictMode == ZSTD_dictMatchState ?
prefixLowestIndex - (U32)(dictEnd - dictBase) :
0;
const U32 dictAndPrefixLength = (U32)(ip - prefixLowest + dictEnd - dictLowest);
(void)dictMode;
@ -537,6 +542,12 @@ size_t ZSTD_compressBlock_lazy_generic(
size_t offset=0;
const BYTE* start=ip+1;
const U32 repIndex = (U32)(ip - base) + 1 - offset_1;
const BYTE* repMatch = (dictMode == ZSTD_dictMatchState
&& repIndex < prefixLowestIndex) ?
dictBase + (repIndex - dictIndexDelta) :
base + repIndex;
/* check repCode */
if ((offset_1>0) & (MEM_read32(ip+1) == MEM_read32(ip+1 - offset_1))) {
/* repcode : we take it */
@ -544,6 +555,18 @@ size_t ZSTD_compressBlock_lazy_generic(
if (depth==0) goto _storeSequence;
}
if (dictMode == ZSTD_dictMatchState
&& ((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */)
&& (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, istart) + 4;
if (depth==0) goto _storeSequence;
} else if ( dictMode == ZSTD_noDict
&& ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) {
matchLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
if (depth==0) goto _storeSequence;
}
/* first search (depth 0) */
{ size_t offsetFound = 99999999;
size_t const ml2 = searchMax(ms, cParams, ip, iend, &offsetFound);