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minor refactoring

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This commit is contained in:
Yann Collet 2016-01-01 07:29:39 +01:00
parent 72e84cfd0f
commit 1358f91ec4
1 changed files with 24 additions and 88 deletions
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112
lib/zstd_compress.c
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@ -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);
}