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shortened repcode match finder implementation

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This commit is contained in:
Yann Collet 2017-11-15 14:37:40 -08:00
parent d7e9805028
commit 61c2d70c86
1 changed files with 28 additions and 51 deletions
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79
lib/compress/zstd_opt.c
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@ -265,59 +265,36 @@ FORCE_INLINE_TEMPLATE
size_t bestLength = minMatchLen-1;
/* check repCode */
#if 1
if (!extDict) /*static*/ {
U32 const lastR = ZSTD_REP_NUM + ll0;
{ U32 const lastR = ZSTD_REP_NUM + ll0;
U32 repCode;
for (repCode = ll0; repCode < lastR; repCode++) {
S32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
if ( (repOffset > 0)
&& (repOffset < (S32)(ip-prefixStart)) /* within current mem segment */
&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch))) {
U32 const repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch;
/* save longer solution */
if (repLen > bestLength) {
DEBUGLOG(8, "current %u : found rep%u match of size%3u",
current, repCode - ll0, repLen);
bestLength = repLen;
matches[mnum].off = repCode - ll0;
matches[mnum].len = (U32)repLen;
mnum++;
if ( (repLen > ZSTD_OPT_NUM)
| (ip+repLen == iLimit) ) { /* best possible */
return mnum;
} } } }
} else { /* extDict */
U32 const lastR = ZSTD_REP_NUM + ll0;
U32 repCode;
for (repCode=ll0; repCode<lastR; repCode++) {
const S32 repCur = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
const U32 repIndex = (U32)(current - repCur);
const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
const BYTE* const repMatch = repBase + repIndex;
if ( (repCur > 0 && repCur <= (S32)current)
&& (((U32)((dictLimit-1) - repIndex) >= 3) & (repIndex>windowLow)) /* intentional overflow */
&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) {
/* repcode detected we should take it */
const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iLimit;
U32 const repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, repEnd, prefixStart) + minMatch;
/* save longer solution */
if (repLen > bestLength) {
DEBUGLOG(8, "current %u : found rep%u match of size%3u",
current, repCode - ll0, repLen);
bestLength = repLen;
matches[mnum].off = repCode - ll0;
matches[mnum].len = (U32)repLen;
mnum++;
if ( (repLen > ZSTD_OPT_NUM)
| (ip+repLen == iLimit) ) { /* best possible */
return mnum;
} } } }
}
#else
(void)ll0; (void)rep; (void)minMatch;
#endif
U32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode];
U32 const repIndex = current - repOffset;
U32 repLen = 0;
assert(repOffset <= current);
assert(current >= dictLimit);
if (!extDict /*static*/ || (repIndex>=dictLimit)) {
if ( (repOffset-1 /* intentional overflow, discards 0 and -1 */ < current-dictLimit) /* within current mem segment */
&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch))) {
repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch;
}
} else { /* extDict */
const BYTE* const repMatch = dictBase + repIndex;
if ( ((repOffset-1) /*intentional overflow*/ < current)
& (((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow */ & (repIndex > windowLow))
&& (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) {
repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch;
} }
/* save longer solution */
if (repLen > bestLength) {
bestLength = repLen;
matches[mnum].off = repCode - ll0;
matches[mnum].len = (U32)repLen;
mnum++;
if ( (repLen > ZSTD_OPT_NUM)
| (ip+repLen == iLimit) ) { /* best possible */
return mnum;
} } } }
/* HC3 match finder */
if ((mls == 3) /*static*/ && (bestLength < mls)) {