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minor refactoring

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This commit is contained in:
Yann Collet 2016-01-01 07:47:58 +01:00
parent 1358f91ec4
commit 2cc12cb3cb
1 changed files with 47 additions and 119 deletions
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166
lib/zstd_compress.c
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@ -1093,79 +1093,6 @@ static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, co
}
FORCE_INLINE /* inlining is important to hardwire a hot branch (template emulation) */
size_t ZSTD_insertBtAndFindBestMatch (
ZSTD_CCtx* zc,
const BYTE* const ip, const BYTE* const iend,
size_t* offsetPtr,
U32 nbCompares, const U32 mls)
{
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 U32 current = (U32)(ip-base);
const U32 btLow = btMask >= current ? 0 : current - btMask;
const U32 windowLow = zc->lowLimit;
U32* smallerPtr = bt + 2*(current&btMask);
U32* largerPtr = bt + 2*(current&btMask) + 1;
size_t bestLength = 0;
U32 matchEndIdx = current+8;
U32 dummy32; /* to be nullified at the end */
hashTable[h] = current; /* Update Hash Table */
while (nbCompares-- && (matchIndex > windowLow))
{
U32* nextPtr = bt + 2*(matchIndex & btMask);
const BYTE* match = base + matchIndex;
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
if (match[matchLength] == ip[matchLength])
matchLength += ZSTD_count(ip+matchLength+1, match+matchLength+1, iend) +1;
if (matchLength > bestLength)
{
if (matchLength > matchEndIdx - matchIndex)
matchEndIdx = matchIndex + (U32)matchLength;
if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit(current-matchIndex+1) - ZSTD_highbit((U32)offsetPtr[0]+1)) )
bestLength = matchLength, *offsetPtr = current - matchIndex;
if (ip+matchLength == iend) /* equal : no way to know if inf or sup */
break; /* drop, to guarantee consistency (miss a little bit of compression) */
}
if (match[matchLength] < ip[matchLength])
{
/* 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;
zc->nextToUpdate = (matchEndIdx > current + 8) ? matchEndIdx - 8 : current+1;
return bestLength;
}
static void ZSTD_updateTree(ZSTD_CCtx* zc, const BYTE* const ip, const BYTE* const iend, const U32 nbCompares, const U32 mls)
{
const BYTE* const base = zc->base;
@ -1176,54 +1103,13 @@ static void ZSTD_updateTree(ZSTD_CCtx* zc, const BYTE* const ip, const BYTE* con
idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 0);
}
/** Tree updater, providing best match */
FORCE_INLINE /* inlining is important to hardwire a hot branch (template emulation) */
size_t ZSTD_BtFindBestMatch (
ZSTD_CCtx* zc,
const BYTE* const ip, const BYTE* const iLimit,
size_t* offsetPtr,
const U32 maxNbAttempts, const U32 mls)
{
if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */
ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls);
return ZSTD_insertBtAndFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, mls);
}
FORCE_INLINE size_t ZSTD_BtFindBestMatch_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_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4);
case 5 : return ZSTD_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5);
case 6 : return ZSTD_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6);
}
}
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;
const U32 target = (U32)(ip - base);
U32 idx = zc->nextToUpdate;
for( ; idx < target ; )
idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 1);
}
FORCE_INLINE /* inlining is important to hardwire a hot branch (template emulation) */
size_t ZSTD_insertBtAndFindBestMatch_extDict (
size_t ZSTD_insertBtAndFindBestMatch (
ZSTD_CCtx* zc,
const BYTE* const ip, const BYTE* const iend,
size_t* offsetPtr,
U32 nbCompares, const U32 mls)
U32 nbCompares, const U32 mls,
U32 extDict)
{
U32* const hashTable = zc->hashTable;
const U32 hashLog = zc->params.hashLog;
@ -1255,7 +1141,7 @@ size_t ZSTD_insertBtAndFindBestMatch_extDict (
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
const BYTE* match;
if (matchIndex+matchLength >= dictLimit)
if ((!extDict) || (matchIndex+matchLength >= dictLimit))
{
match = base + matchIndex;
if (match[matchLength] == ip[matchLength])
@ -1305,6 +1191,48 @@ size_t ZSTD_insertBtAndFindBestMatch_extDict (
return bestLength;
}
/** Tree updater, providing best match */
FORCE_INLINE /* inlining is important to hardwire a hot branch (template emulation) */
size_t ZSTD_BtFindBestMatch (
ZSTD_CCtx* zc,
const BYTE* const ip, const BYTE* const iLimit,
size_t* offsetPtr,
const U32 maxNbAttempts, const U32 mls)
{
if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */
ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls);
return ZSTD_insertBtAndFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, mls, 0);
}
FORCE_INLINE size_t ZSTD_BtFindBestMatch_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_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 4);
case 5 : return ZSTD_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 5);
case 6 : return ZSTD_BtFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, 6);
}
}
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;
const U32 target = (U32)(ip - base);
U32 idx = zc->nextToUpdate;
for( ; idx < target ; )
idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 1);
}
/** Tree updater, providing best match */
FORCE_INLINE /* inlining is important to hardwire a hot branch (template emulation) */
size_t ZSTD_BtFindBestMatch_extDict (
@ -1315,7 +1243,7 @@ size_t ZSTD_BtFindBestMatch_extDict (
{
if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */
ZSTD_updateTree_extDict(zc, ip, iLimit, maxNbAttempts, mls);
return ZSTD_insertBtAndFindBestMatch_extDict(zc, ip, iLimit, offsetPtr, maxNbAttempts, mls);
return ZSTD_insertBtAndFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, mls, 1);
}