From: Yann Collet Date: Fri, 1 Jan 2016 06:29:39 +0000 (+0100) Subject: minor refactoring X-Git-Tag: v0.4.6~2^2~15 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1358f91ec4a5a202158c161488d19e0f7c23925d;p=thirdparty%2Fzstd.git minor refactoring --- diff --git a/lib/zstd_compress.c b/lib/zstd_compress.c index 2efb9289b..51157306b 100644 --- a/lib/zstd_compress.c +++ b/lib/zstd_compress.c @@ -1013,10 +1013,11 @@ size_t ZSTD_compressBlock_fast_extDict(ZSTD_CCtx* ctx, /* ************************************* * Binary Tree search ***************************************/ -/*! ZSTD_insertBt1 : add one or multiple positions to tree +/** ZSTD_insertBt1 : add one or multiple positions to tree * @ip : assumed <= iend-8 * @return : nb of positions added */ -static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, const BYTE* const iend, U32 nbCompares) +static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, const BYTE* const iend, U32 nbCompares, + U32 extDict) { U32* const hashTable = zc->hashTable; const U32 hashLog = zc->params.hashLog; @@ -1027,6 +1028,10 @@ static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, co U32 matchIndex = hashTable[h]; size_t commonLengthSmaller=0, commonLengthLarger=0; const BYTE* const base = zc->base; + const BYTE* const dictBase = zc->dictBase; + const U32 dictLimit = zc->dictLimit; + const BYTE* const dictEnd = dictBase + dictLimit; + const BYTE* const prefixStart = base + dictLimit; const BYTE* match = base + matchIndex; const U32 current = (U32)(ip-base); const U32 btLow = btMask >= current ? 0 : current - btMask; @@ -1043,17 +1048,27 @@ static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, co U32* nextPtr = bt + 2*(matchIndex & btMask); size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ - match = base + matchIndex; - if (match[matchLength] == ip[matchLength]) - matchLength += ZSTD_count(ip+matchLength+1, match+matchLength+1, iend) +1; + if ((!extDict) || (matchIndex+matchLength >= dictLimit)) + { + match = base + matchIndex; + if (match[matchLength] == ip[matchLength]) + matchLength += ZSTD_count(ip+matchLength+1, match+matchLength+1, iend) +1; + } + else + { + match = dictBase + matchIndex; + matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); + if (matchIndex+matchLength >= dictLimit) + match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ + } if (matchLength > matchEndIdx - matchIndex) matchEndIdx = matchIndex + (U32)matchLength; if (ip+matchLength == iend) /* equal : no way to know if inf or sup */ - break; /* drop , to guarantee consistency ; miss a bit of compression, but required to not corrupt the tree */ + break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt the tree */ - if (match[matchLength] < ip[matchLength]) + if (match[matchLength] < ip[matchLength]) /* necessarily within correct buffer */ { /* match is smaller than current */ *smallerPtr = matchIndex; /* update smaller idx */ @@ -1158,7 +1173,7 @@ static void ZSTD_updateTree(ZSTD_CCtx* zc, const BYTE* const ip, const BYTE* con U32 idx = zc->nextToUpdate; for( ; idx < target ; ) - idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares); + idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 0); } @@ -1192,85 +1207,6 @@ FORCE_INLINE size_t ZSTD_BtFindBestMatch_selectMLS ( } -/** ZSTD_insertBt1_extDict : add one or multiple positions to tree -* @ip : assumed <= iend-8 -* @return : nb of positions added */ -static U32 ZSTD_insertBt1_extDict(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, const BYTE* const iend, U32 nbCompares) -{ - U32* const hashTable = zc->hashTable; - const U32 hashLog = zc->params.hashLog; - const size_t h = ZSTD_hashPtr(ip, hashLog, mls); - U32* const bt = zc->contentTable; - const U32 btLog = zc->params.contentLog - 1; - const U32 btMask= (1 << btLog) - 1; - U32 matchIndex = hashTable[h]; - size_t commonLengthSmaller=0, commonLengthLarger=0; - const BYTE* const base = zc->base; - const BYTE* const dictBase = zc->dictBase; - const U32 dictLimit = zc->dictLimit; - const BYTE* const dictEnd = dictBase + dictLimit; - const BYTE* const prefixStart = base + dictLimit; - const BYTE* match = base + matchIndex; - const U32 current = (U32)(ip-base); - const U32 btLow = btMask >= current ? 0 : current - btMask; - U32* smallerPtr = bt + 2*(current&btMask); - U32* largerPtr = bt + 2*(current&btMask) + 1; - U32 dummy32; /* to be nullified at the end */ - const U32 windowLow = zc->lowLimit; - U32 matchEndIdx = current+8; - - hashTable[h] = current; /* Update Hash Table */ - - while (nbCompares-- && (matchIndex > windowLow)) - { - U32* nextPtr = bt + 2*(matchIndex & btMask); - size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ - - if (matchIndex+matchLength >= dictLimit) - { - match = base + matchIndex; - if (match[matchLength] == ip[matchLength]) - matchLength += ZSTD_count(ip+matchLength+1, match+matchLength+1, iend) +1; - } - else - { - match = dictBase + matchIndex; - matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); - if (matchIndex+matchLength >= dictLimit) - match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ - } - - if (matchLength > matchEndIdx - matchIndex) - matchEndIdx = matchIndex + (U32)matchLength; - - if (ip+matchLength == iend) /* equal : no way to know if inf or sup */ - break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt the tree */ - - if (match[matchLength] < ip[matchLength]) /* necessarily within correct buffer */ - { - /* match is smaller than current */ - *smallerPtr = matchIndex; /* update smaller idx */ - commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ - if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ - smallerPtr = nextPtr+1; /* new "smaller" => larger of match */ - matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ - } - else - { - /* match is larger than current */ - *largerPtr = matchIndex; - commonLengthLarger = matchLength; - if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ - largerPtr = nextPtr; - matchIndex = nextPtr[0]; - } - } - - *smallerPtr = *largerPtr = 0; - return (matchEndIdx > current + 8) ? matchEndIdx - current - 8 : 1; -} - - static void ZSTD_updateTree_extDict(ZSTD_CCtx* zc, const BYTE* const ip, const BYTE* const iend, const U32 nbCompares, const U32 mls) { const BYTE* const base = zc->base; @@ -1278,7 +1214,7 @@ static void ZSTD_updateTree_extDict(ZSTD_CCtx* zc, const BYTE* const ip, const B U32 idx = zc->nextToUpdate; for( ; idx < target ; ) - idx += ZSTD_insertBt1_extDict(zc, base+idx, mls, iend, nbCompares); + idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 1); }