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refactored fix to be more generic and applicable to both btlazy2 and btopt

dev
Yann Collet 2016-02-15 17:06:29 +01:00
parent b37e0a9241
commit b8a6f6824b
2 changed files with 28 additions and 19 deletions
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43
lib/zstd_compress.c
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@ -1172,6 +1172,7 @@ static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, co
U32 dummy32; /* to be nullified at the end */
const U32 windowLow = zc->lowLimit;
U32 matchEndIdx = current+8;
size_t bestLength = 8;
U32 predictedSmall = *(bt + 2*((current-1)&btMask) + 0);
U32 predictedLarge = *(bt + 2*((current-1)&btMask) + 1);
predictedSmall += (predictedSmall>0);
@ -1213,8 +1214,11 @@ static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, co
match = base + matchIndex; /* to prepare for next usage of match[matchLength] */
}
if (matchLength > matchEndIdx - matchIndex)
matchEndIdx = matchIndex + (U32)matchLength;
if (matchLength > bestLength) {
bestLength = 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 */
@ -1236,7 +1240,9 @@ static U32 ZSTD_insertBt1(ZSTD_CCtx* zc, const BYTE* const ip, const U32 mls, co
} }
*smallerPtr = *largerPtr = 0;
return (matchEndIdx > current + 8) ? (matchEndIdx - current) - 8 : 1;
if (bestLength > 384) return MIN(192, (U32)(bestLength - 384));
if (matchEndIdx > current + 8) return matchEndIdx - current - 8;
return 1;
}
@ -1319,20 +1325,14 @@ static size_t ZSTD_insertBtAndFindBestMatch (
}
#define BT_MAXREF_1 16
#define BT_MAXREF_2 128
#define BT_MAXREF (BT_MAXREF_1 + BT_MAXREF_2)
static void ZSTD_updateTree(ZSTD_CCtx* zc, const BYTE* const ip, const BYTE* const iend, const U32 nbCompares, const U32 mls, U32 extDict, U32 noSkip)
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;
const U32 target = (U32)(ip - base);
U32 idx = zc->nextToUpdate;
if ((!noSkip) && (idx + BT_MAXREF < target)) {
U32 t2 = idx + BT_MAXREF_1;
while(idx < t2) idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, extDict);
idx = target - BT_MAXREF_2;
}
while(idx < target) idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, extDict);
while(idx < target)
idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 0);
}
/** Tree updater, providing best match */
@ -1343,7 +1343,7 @@ static size_t ZSTD_BtFindBestMatch (
const U32 maxNbAttempts, const U32 mls)
{
if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */
ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls, 0, 0);
ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls);
return ZSTD_insertBtAndFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, mls, 0);
}
@ -1364,6 +1364,15 @@ static size_t ZSTD_BtFindBestMatch_selectMLS (
}
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;
while (idx < target) idx += ZSTD_insertBt1(zc, base+idx, mls, iend, nbCompares, 1);
}
/** Tree updater, providing best match */
static size_t ZSTD_BtFindBestMatch_extDict (
@ -1373,7 +1382,7 @@ static size_t ZSTD_BtFindBestMatch_extDict (
const U32 maxNbAttempts, const U32 mls)
{
if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */
ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls, 1, 0);
ZSTD_updateTree_extDict(zc, ip, iLimit, maxNbAttempts, mls);
return ZSTD_insertBtAndFindBestMatch(zc, ip, iLimit, offsetPtr, maxNbAttempts, mls, 1);
}
@ -2054,7 +2063,7 @@ static size_t ZSTD_loadDictionaryContent(ZSTD_CCtx* zc, const void* src, size_t
case ZSTD_btlazy2:
case ZSTD_btopt:
ZSTD_updateTree(zc, iend-8, iend, 1 << zc->params.searchLog, zc->params.searchLength, 0, 1);
ZSTD_updateTree(zc, iend-8, iend, 1 << zc->params.searchLog, zc->params.searchLength);
break;
default:
@ -2327,7 +2336,7 @@ static const ZSTD_parameters ZSTD_defaultParameters[4][ZSTD_MAX_CLEVEL+1] = {
{ 0, 17, 17, 16, 6, 4, 4, ZSTD_lazy2 }, /* level 10 */
{ 0, 17, 17, 17, 7, 4, 4, ZSTD_lazy2 }, /* level 11 */
{ 0, 17, 17, 17, 8, 4, 4, ZSTD_lazy2 }, /* level 12 */
{ 0, 17, 18, 17, 5, 4, 4, ZSTD_btlazy2 }, /* level 13 */
{ 0, 17, 17, 17, 9, 4, 4, ZSTD_lazy2 }, /* level 13 */
{ 0, 17, 18, 16, 5, 4, 20, ZSTD_btopt }, /* level 14 */
{ 0, 17, 18, 16, 9, 4, 48, ZSTD_btopt }, /* level 15 */
{ 0, 17, 18, 17, 7, 4,128, ZSTD_btopt }, /* level 16 */

4
lib/zstd_opt.h
View File

@ -264,7 +264,7 @@ U32 ZSTD_BtGetAllMatches (
const U32 maxNbAttempts, const U32 mls, ZSTD_match_t* matches, U32 minml)
{
if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */
ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls, 0, 0);
ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls);
return ZSTD_insertBtAndGetAllMatches(zc, ip, iLimit, maxNbAttempts, mls, 0, matches, minml);
}
@ -292,7 +292,7 @@ U32 ZSTD_BtGetAllMatches_extDict (
const U32 maxNbAttempts, const U32 mls, ZSTD_match_t* matches, U32 minml)
{
if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */
ZSTD_updateTree(zc, ip, iLimit, maxNbAttempts, mls, 1, 0);
ZSTD_updateTree_extDict(zc, ip, iLimit, maxNbAttempts, mls);
return ZSTD_insertBtAndGetAllMatches(zc, ip, iLimit, maxNbAttempts, mls, 1, matches, minml);
}