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fixed doc typo

dev
Yann Collet 2016-08-02 14:26:00 +02:00
parent de4c04f6c2
commit 346efccc35
3 changed files with 41 additions and 35 deletions
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4
NEWS
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@ -1,3 +1,7 @@
v0.8.1
Changed : -i# now selects benchmark time in second
Fixed : ZSTD_compress* can now compress > 4 GB in a single pass, reported by Nick Terrell
v0.8.0
Improved : better speed on clang and gcc -O2, thanks to Eric Biggers
New : Build on FreeBSD and DragonFly, thanks to JrMarino

70
lib/compress/zstd_compress.c
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@ -2244,6 +2244,21 @@ static size_t ZSTD_compress_generic (ZSTD_CCtx* cctx,
if (dstCapacity < ZSTD_blockHeaderSize + MIN_CBLOCK_SIZE) return ERROR(dstSize_tooSmall); /* not enough space to store compressed block */
if (remaining < blockSize) blockSize = remaining;
/* preemptive overflow correction */
if (cctx->lowLimit > (1<<30)) {
U32 const btplus = (cctx->params.cParams.strategy == ZSTD_btlazy2) | (cctx->params.cParams.strategy == ZSTD_btopt);
U32 const chainMask = (1 << (cctx->params.cParams.chainLog - btplus)) - 1;
U32 const newLowLimit = cctx->lowLimit & chainMask; /* preserve position % chainSize */
U32 const correction = cctx->lowLimit - newLowLimit;
ZSTD_reduceIndex(cctx, correction);
cctx->base += correction;
cctx->dictBase += correction;
cctx->lowLimit = newLowLimit;
cctx->dictLimit -= correction;
if (cctx->nextToUpdate < correction) cctx->nextToUpdate = 0;
else cctx->nextToUpdate -= correction;
}
if ((U32)(ip+blockSize - cctx->base) > cctx->loadedDictEnd + maxDist) {
/* enforce maxDist */
U32 const newLowLimit = (U32)(ip+blockSize - cctx->base) - maxDist;
@ -2317,7 +2332,7 @@ static size_t ZSTD_writeFrameHeader(void* dst, size_t dstCapacity,
}
static size_t ZSTD_compressContinue_internal (ZSTD_CCtx* zc,
static size_t ZSTD_compressContinue_internal (ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
U32 frame, U32 lastFrameChunk)
@ -2325,53 +2340,40 @@ static size_t ZSTD_compressContinue_internal (ZSTD_CCtx* zc,
const BYTE* const ip = (const BYTE*) src;
size_t fhSize = 0;
if (zc->stage==ZSTDcs_created) return ERROR(stage_wrong); /* missing init (ZSTD_compressBegin) */
if (cctx->stage==ZSTDcs_created) return ERROR(stage_wrong); /* missing init (ZSTD_compressBegin) */
if (frame && (zc->stage==ZSTDcs_init)) {
fhSize = ZSTD_writeFrameHeader(dst, dstCapacity, zc->params, zc->frameContentSize, zc->dictID);
if (frame && (cctx->stage==ZSTDcs_init)) {
fhSize = ZSTD_writeFrameHeader(dst, dstCapacity, cctx->params, cctx->frameContentSize, cctx->dictID);
if (ZSTD_isError(fhSize)) return fhSize;
dstCapacity -= fhSize;
dst = (char*)dst + fhSize;
zc->stage = ZSTDcs_ongoing;
cctx->stage = ZSTDcs_ongoing;
}
/* Check if blocks follow each other */
if (src != zc->nextSrc) {
if (src != cctx->nextSrc) {
/* not contiguous */
ptrdiff_t const delta = zc->nextSrc - ip;
zc->lowLimit = zc->dictLimit;
zc->dictLimit = (U32)(zc->nextSrc - zc->base);
zc->dictBase = zc->base;
zc->base -= delta;
zc->nextToUpdate = zc->dictLimit;
if (zc->dictLimit - zc->lowLimit < HASH_READ_SIZE) zc->lowLimit = zc->dictLimit; /* too small extDict */
ptrdiff_t const delta = cctx->nextSrc - ip;
cctx->lowLimit = cctx->dictLimit;
cctx->dictLimit = (U32)(cctx->nextSrc - cctx->base);
cctx->dictBase = cctx->base;
cctx->base -= delta;
cctx->nextToUpdate = cctx->dictLimit;
if (cctx->dictLimit - cctx->lowLimit < HASH_READ_SIZE) cctx->lowLimit = cctx->dictLimit; /* too small extDict */
}
/* preemptive overflow correction */
if (zc->lowLimit > (1<<30)) {
U32 const btplus = (zc->params.cParams.strategy == ZSTD_btlazy2) | (zc->params.cParams.strategy == ZSTD_btopt);
U32 const chainMask = (1 << (zc->params.cParams.chainLog - btplus)) - 1;
U32 const newLowLimit = zc->lowLimit & chainMask; /* preserve position % chainSize */
U32 const correction = zc->lowLimit - newLowLimit;
ZSTD_reduceIndex(zc, correction);
zc->base += correction;
zc->dictBase += correction;
zc->lowLimit = newLowLimit;
zc->dictLimit -= correction;
if (zc->nextToUpdate < correction) zc->nextToUpdate = 0;
else zc->nextToUpdate -= correction;
/* if input and dictionary overlap : reduce dictionary (area presumed modified by input) */
if ((ip+srcSize > cctx->dictBase + cctx->lowLimit) & (ip < cctx->dictBase + cctx->dictLimit)) {
ptrdiff_t const highInputIdx = (ip + srcSize) - cctx->dictBase;
U32 const lowLimitMax = (highInputIdx > (ptrdiff_t)cctx->dictLimit) ? cctx->dictLimit : (U32)highInputIdx;
cctx->lowLimit = lowLimitMax;
}
/* if input and dictionary overlap : reduce dictionary (presumed modified by input) */
if ((ip+srcSize > zc->dictBase + zc->lowLimit) && (ip < zc->dictBase + zc->dictLimit)) {
zc->lowLimit = (U32)(ip + srcSize - zc->dictBase);
if (zc->lowLimit > zc->dictLimit) zc->lowLimit = zc->dictLimit;
}
cctx->nextSrc = ip + srcSize;
zc->nextSrc = ip + srcSize;
{ size_t const cSize = frame ?
ZSTD_compress_generic (zc, dst, dstCapacity, src, srcSize, lastFrameChunk) :
ZSTD_compressBlock_internal (zc, dst, dstCapacity, src, srcSize);
ZSTD_compress_generic (cctx, dst, dstCapacity, src, srcSize, lastFrameChunk) :
ZSTD_compressBlock_internal (cctx, dst, dstCapacity, src, srcSize);
if (ZSTD_isError(cSize)) return cSize;
return cSize + fhSize;
}

2
zstd_compression_format.md
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@ -503,7 +503,7 @@ Compressed and regenerated size fields follow little-endian convention.
#### Huffman Tree description
This section is only present when literals block type is `Compressed` (`0`).
This section is only present when literals block type is `Compressed` (`2`).
Prefix coding represents symbols from an a priori known alphabet
by bit sequences (codewords), one codeword for each symbol,