<pre><b>size_t ZSTD_compress( void* dst, size_t dstCapacity,
const void* src, size_t srcSize,
int compressionLevel);
-</b><p> Compresses `src` content as a single zstd compressed frame into already allocated `dst`.
- Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
- @return : compressed size written into `dst` (<= `dstCapacity),
- or an error code if it fails (which can be tested using ZSTD_isError()).
+</b><p> Compresses `src` content as a single zstd compressed frame into already allocated `dst`.
+ Hint : compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
+ @return : compressed size written into `dst` (<= `dstCapacity),
+ or an error code if it fails (which can be tested using ZSTD_isError()).
</p></pre><BR>
<pre><b>size_t ZSTD_decompress( void* dst, size_t dstCapacity,
const void* src, size_t compressedSize);
-</b><p> `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames.
- `dstCapacity` is an upper bound of originalSize.
- If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data.
- @return : the number of bytes decompressed into `dst` (<= `dstCapacity`),
- or an errorCode if it fails (which can be tested using ZSTD_isError()).
+</b><p> `compressedSize` : must be the _exact_ size of some number of compressed and/or skippable frames.
+ `dstCapacity` is an upper bound of originalSize.
+ If user cannot imply a maximum upper bound, it's better to use streaming mode to decompress data.
+ @return : the number of bytes decompressed into `dst` (<= `dstCapacity`),
+ or an errorCode if it fails (which can be tested using ZSTD_isError()).
</p></pre><BR>
<pre><b>unsigned long long ZSTD_getDecompressedSize(const void* src, size_t srcSize);
-</b><p> NOTE: This function is planned to be obsolete, in favour of ZSTD_getFrameContentSize.
- ZSTD_getFrameContentSize functions the same way, returning the decompressed size of a single
- frame, but distinguishes empty frames from frames with an unknown size, or errors.
-
- Additionally, ZSTD_findDecompressedSize can be used instead. It can handle multiple
- concatenated frames in one buffer, and so is more general.
- As a result however, it requires more computation and entire frames to be passed to it,
- as opposed to ZSTD_getFrameContentSize which requires only a single frame's header.
-
- 'src' is the start of a zstd compressed frame.
- @return : content size to be decompressed, as a 64-bits value _if known_, 0 otherwise.
- note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode.
- When `return==0`, data to decompress could be any size.
- In which case, it's necessary to use streaming mode to decompress data.
- Optionally, application can still use ZSTD_decompress() while relying on implied limits.
- (For example, data may be necessarily cut into blocks <= 16 KB).
- note 2 : decompressed size is always present when compression is done with ZSTD_compress()
- note 3 : decompressed size can be very large (64-bits value),
- potentially larger than what local system can handle as a single memory segment.
- In which case, it's necessary to use streaming mode to decompress data.
- note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified.
- Always ensure result fits within application's authorized limits.
- Each application can set its own limits.
- note 5 : when `return==0`, if precise failure cause is needed, use ZSTD_getFrameParams() to know more.
+</b><p> NOTE: This function is planned to be obsolete, in favour of ZSTD_getFrameContentSize.
+ ZSTD_getFrameContentSize functions the same way, returning the decompressed size of a single
+ frame, but distinguishes empty frames from frames with an unknown size, or errors.
+
+ Additionally, ZSTD_findDecompressedSize can be used instead. It can handle multiple
+ concatenated frames in one buffer, and so is more general.
+ As a result however, it requires more computation and entire frames to be passed to it,
+ as opposed to ZSTD_getFrameContentSize which requires only a single frame's header.
+
+ 'src' is the start of a zstd compressed frame.
+ @return : content size to be decompressed, as a 64-bits value _if known_, 0 otherwise.
+ note 1 : decompressed size is an optional field, that may not be present, especially in streaming mode.
+ When `return==0`, data to decompress could be any size.
+ In which case, it's necessary to use streaming mode to decompress data.
+ Optionally, application can still use ZSTD_decompress() while relying on implied limits.
+ (For example, data may be necessarily cut into blocks <= 16 KB).
+ note 2 : decompressed size is always present when compression is done with ZSTD_compress()
+ note 3 : decompressed size can be very large (64-bits value),
+ potentially larger than what local system can handle as a single memory segment.
+ In which case, it's necessary to use streaming mode to decompress data.
+ note 4 : If source is untrusted, decompressed size could be wrong or intentionally modified.
+ Always ensure result fits within application's authorized limits.
+ Each application can set its own limits.
+ note 5 : when `return==0`, if precise failure cause is needed, use ZSTD_getFrameParams() to know more.
</p></pre><BR>
<h3>Helper functions</h3><pre></pre><b><pre>int ZSTD_maxCLevel(void); </b>/*!< maximum compression level available */<b>
</pre></b><BR>
<a name="Chapter4"></a><h2>Explicit memory management</h2><pre></pre>
-<h3>Compression context</h3><pre> When compressing many times,
- it is recommended to allocate a context just once, and re-use it for each successive compression operation.
- This will make workload friendlier for system's memory.
- Use one context per thread for parallel execution in multi-threaded environments.
+<h3>Compression context</h3><pre> When compressing many times,
+ it is recommended to allocate a context just once, and re-use it for each successive compression operation.
+ This will make workload friendlier for system's memory.
+ Use one context per thread for parallel execution in multi-threaded environments.
</pre><b><pre>typedef struct ZSTD_CCtx_s ZSTD_CCtx;
ZSTD_CCtx* ZSTD_createCCtx(void);
size_t ZSTD_freeCCtx(ZSTD_CCtx* cctx);
</pre></b><BR>
<pre><b>size_t ZSTD_compressCCtx(ZSTD_CCtx* ctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize, int compressionLevel);
-</b><p> Same as ZSTD_compress(), requires an allocated ZSTD_CCtx (see ZSTD_createCCtx()).
+</b><p> Same as ZSTD_compress(), requires an allocated ZSTD_CCtx (see ZSTD_createCCtx()).
</p></pre><BR>
-<h3>Decompression context</h3><pre> When decompressing many times,
- it is recommended to allocate a context just once, and re-use it for each successive compression operation.
- This will make workload friendlier for system's memory.
- Use one context per thread for parallel execution in multi-threaded environments.
+<h3>Decompression context</h3><pre> When decompressing many times,
+ it is recommended to allocate a context just once, and re-use it for each successive compression operation.
+ This will make workload friendlier for system's memory.
+ Use one context per thread for parallel execution in multi-threaded environments.
</pre><b><pre>typedef struct ZSTD_DCtx_s ZSTD_DCtx;
ZSTD_DCtx* ZSTD_createDCtx(void);
size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx);
</pre></b><BR>
<pre><b>size_t ZSTD_decompressDCtx(ZSTD_DCtx* ctx, void* dst, size_t dstCapacity, const void* src, size_t srcSize);
-</b><p> Same as ZSTD_decompress(), requires an allocated ZSTD_DCtx (see ZSTD_createDCtx()).
+</b><p> Same as ZSTD_decompress(), requires an allocated ZSTD_DCtx (see ZSTD_createDCtx()).
</p></pre><BR>
<a name="Chapter5"></a><h2>Simple dictionary API</h2><pre></pre>
/* entropy tables always have same size */
static size_t const hufCTable_size = HUF_CTABLE_SIZE(255);
-static size_t const litlengthCTable_size = FSE_CTABLE_SIZE_U32(LLFSELog, MaxLL) * sizeof(FSE_CTable);
-static size_t const offcodeCTable_size = FSE_CTABLE_SIZE_U32(OffFSELog, MaxOff) * sizeof(FSE_CTable);
-static size_t const matchlengthCTable_size = FSE_CTABLE_SIZE_U32(MLFSELog, MaxML) * sizeof(FSE_CTable);
+static size_t const litlengthCTable_size = FSE_CTABLE_SIZE(LLFSELog, MaxLL);
+static size_t const offcodeCTable_size = FSE_CTABLE_SIZE(OffFSELog, MaxOff);
+static size_t const matchlengthCTable_size = FSE_CTABLE_SIZE(MLFSELog, MaxML);
static size_t const entropyScratchSpace_size = HUF_WORKSPACE_SIZE;
FSE_CTable* offcodeCTable;
FSE_CTable* matchlengthCTable;
FSE_CTable* litlengthCTable;
- unsigned* tmpCounters;
+ unsigned* entropyScratchSpace;
};
ZSTD_CCtx* ZSTD_createCCtx(void)
zc->litlengthCTable = (FSE_CTable*) ptr;
ptr = (char*)ptr + litlengthCTable_size;
assert(((size_t)ptr & 3) == 0); /* ensure correct alignment */
- zc->tmpCounters = (unsigned*) ptr;
+ zc->entropyScratchSpace = (unsigned*) ptr;
} }
/* init params */
assert((char*)zc->offcodeCTable == (char*)zc->hufCTable + hufCTable_size);
assert((char*)zc->matchlengthCTable == (char*)zc->offcodeCTable + offcodeCTable_size);
assert((char*)zc->litlengthCTable == (char*)zc->matchlengthCTable + matchlengthCTable_size);
- assert((char*)zc->tmpCounters == (char*)zc->litlengthCTable + litlengthCTable_size);
- ptr = (char*)zc->tmpCounters + entropyScratchSpace_size;
+ assert((char*)zc->entropyScratchSpace == (char*)zc->litlengthCTable + litlengthCTable_size);
+ ptr = (char*)zc->entropyScratchSpace + entropyScratchSpace_size;
/* opt parser space */
if ((params.cParams.strategy == ZSTD_btopt) || (params.cParams.strategy == ZSTD_btopt2)) {
int const preferRepeat = zc->params.cParams.strategy < ZSTD_lazy ? srcSize <= 1024 : 0;
if (repeat == HUF_repeat_valid && lhSize == 3) singleStream = 1;
cLitSize = singleStream ? HUF_compress1X_repeat(ostart+lhSize, dstCapacity-lhSize, src, srcSize, 255, 11,
- zc->tmpCounters, entropyScratchSpace_size, zc->hufCTable, &repeat, preferRepeat)
+ zc->entropyScratchSpace, entropyScratchSpace_size, zc->hufCTable, &repeat, preferRepeat)
: HUF_compress4X_repeat(ostart+lhSize, dstCapacity-lhSize, src, srcSize, 255, 11,
- zc->tmpCounters, entropyScratchSpace_size, zc->hufCTable, &repeat, preferRepeat);
+ zc->entropyScratchSpace, entropyScratchSpace_size, zc->hufCTable, &repeat, preferRepeat);
if (repeat != HUF_repeat_none) { hType = set_repeat; } /* reused the existing table */
else { zc->hufCTable_repeatMode = HUF_repeat_check; } /* now have a table to reuse */
}
/* CTable for Literal Lengths */
{ U32 max = MaxLL;
- size_t const mostFrequent = FSE_countFast_wksp(count, &max, llCodeTable, nbSeq, zc->tmpCounters);
+ size_t const mostFrequent = FSE_countFast_wksp(count, &max, llCodeTable, nbSeq, zc->entropyScratchSpace);
if ((mostFrequent == nbSeq) && (nbSeq > 2)) {
*op++ = llCodeTable[0];
FSE_buildCTable_rle(CTable_LitLength, (BYTE)max);
/* CTable for Offsets */
{ U32 max = MaxOff;
- size_t const mostFrequent = FSE_countFast_wksp(count, &max, ofCodeTable, nbSeq, zc->tmpCounters);
+ size_t const mostFrequent = FSE_countFast_wksp(count, &max, ofCodeTable, nbSeq, zc->entropyScratchSpace);
if ((mostFrequent == nbSeq) && (nbSeq > 2)) {
*op++ = ofCodeTable[0];
FSE_buildCTable_rle(CTable_OffsetBits, (BYTE)max);
/* CTable for MatchLengths */
{ U32 max = MaxML;
- size_t const mostFrequent = FSE_countFast_wksp(count, &max, mlCodeTable, nbSeq, zc->tmpCounters);
+ size_t const mostFrequent = FSE_countFast_wksp(count, &max, mlCodeTable, nbSeq, zc->entropyScratchSpace);
if ((mostFrequent == nbSeq) && (nbSeq > 2)) {
*op++ = *mlCodeTable;
FSE_buildCTable_rle(CTable_MatchLength, (BYTE)max);
if ( (((U32)((dictLimit-1) - repIndex2) >= 3) & (repIndex2 > lowestIndex)) /* intentional overflow */
&& (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
const BYTE* const repEnd2 = repIndex2 < dictLimit ? dictEnd : iend;
- size_t const repLength2 = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch2+EQUAL_READ32, iend, repEnd2, lowPrefixPtr) + EQUAL_READ32;
+ size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, lowPrefixPtr) + 4;
U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, repLength2-MINMATCH);
hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = current2;
const U32 current = (U32)(ip-base);
const U32 minChain = current > chainSize ? current - chainSize : 0;
int nbAttempts=maxNbAttempts;
- size_t ml=EQUAL_READ32-1;
+ size_t ml=4-1;
/* HC4 match finder */
U32 matchIndex = ZSTD_insertAndFindFirstIndex (zc, ip, mls);
} else {
match = dictBase + matchIndex;
if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
- currentMl = ZSTD_count_2segments(ip+EQUAL_READ32, match+EQUAL_READ32, iLimit, dictEnd, prefixStart) + EQUAL_READ32;
+ currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4;
}
/* save best solution */
/* check repCode */
if ((offset_1>0) & (MEM_read32(ip+1) == MEM_read32(ip+1 - offset_1))) {
/* repcode : we take it */
- matchLength = ZSTD_count(ip+1+EQUAL_READ32, ip+1+EQUAL_READ32-offset_1, iend) + EQUAL_READ32;
+ matchLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
if (depth==0) goto _storeSequence;
}
matchLength = ml2, start = ip, offset=offsetFound;
}
- if (matchLength < EQUAL_READ32) {
+ if (matchLength < 4) {
ip += ((ip-anchor) >> g_searchStrength) + 1; /* jump faster over incompressible sections */
continue;
}
while (ip<ilimit) {
ip ++;
if ((offset) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
- size_t const mlRep = ZSTD_count(ip+EQUAL_READ32, ip+EQUAL_READ32-offset_1, iend) + EQUAL_READ32;
+ size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4;
int const gain2 = (int)(mlRep * 3);
int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offset+1) + 1);
- if ((mlRep >= EQUAL_READ32) && (gain2 > gain1))
+ if ((mlRep >= 4) && (gain2 > gain1))
matchLength = mlRep, offset = 0, start = ip;
}
{ size_t offset2=99999999;
size_t const ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1)); /* raw approx */
int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 4);
- if ((ml2 >= EQUAL_READ32) && (gain2 > gain1)) {
+ if ((ml2 >= 4) && (gain2 > gain1)) {
matchLength = ml2, offset = offset2, start = ip;
continue; /* search a better one */
} }
if ((depth==2) && (ip<ilimit)) {
ip ++;
if ((offset) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
- size_t const ml2 = ZSTD_count(ip+EQUAL_READ32, ip+EQUAL_READ32-offset_1, iend) + EQUAL_READ32;
+ size_t const ml2 = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4;
int const gain2 = (int)(ml2 * 4);
int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 1);
- if ((ml2 >= EQUAL_READ32) && (gain2 > gain1))
+ if ((ml2 >= 4) && (gain2 > gain1))
matchLength = ml2, offset = 0, start = ip;
}
{ size_t offset2=99999999;
size_t const ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1)); /* raw approx */
int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 7);
- if ((ml2 >= EQUAL_READ32) && (gain2 > gain1)) {
+ if ((ml2 >= 4) && (gain2 > gain1)) {
matchLength = ml2, offset = offset2, start = ip;
continue;
} } }
&& ((offset_2>0)
& (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {
/* store sequence */
- matchLength = ZSTD_count(ip+EQUAL_READ32, ip+EQUAL_READ32-offset_2, iend) + EQUAL_READ32;
+ matchLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset; /* swap repcodes */
ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, matchLength-MINMATCH);
ip += matchLength;
if (MEM_read32(ip+1) == MEM_read32(repMatch)) {
/* repcode detected we should take it */
const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
- matchLength = ZSTD_count_2segments(ip+1+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repEnd, prefixStart) + EQUAL_READ32;
+ matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repEnd, prefixStart) + 4;
if (depth==0) goto _storeSequence;
} }
matchLength = ml2, start = ip, offset=offsetFound;
}
- if (matchLength < EQUAL_READ32) {
+ if (matchLength < 4) {
ip += ((ip-anchor) >> g_searchStrength) + 1; /* jump faster over incompressible sections */
continue;
}
if (MEM_read32(ip) == MEM_read32(repMatch)) {
/* repcode detected */
const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
- size_t const repLength = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repEnd, prefixStart) + EQUAL_READ32;
+ size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
int const gain2 = (int)(repLength * 3);
int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offset+1) + 1);
- if ((repLength >= EQUAL_READ32) && (gain2 > gain1))
+ if ((repLength >= 4) && (gain2 > gain1))
matchLength = repLength, offset = 0, start = ip;
} }
size_t const ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1)); /* raw approx */
int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 4);
- if ((ml2 >= EQUAL_READ32) && (gain2 > gain1)) {
+ if ((ml2 >= 4) && (gain2 > gain1)) {
matchLength = ml2, offset = offset2, start = ip;
continue; /* search a better one */
} }
if (MEM_read32(ip) == MEM_read32(repMatch)) {
/* repcode detected */
const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
- size_t const repLength = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repEnd, prefixStart) + EQUAL_READ32;
+ size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
int const gain2 = (int)(repLength * 4);
int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 1);
- if ((repLength >= EQUAL_READ32) && (gain2 > gain1))
+ if ((repLength >= 4) && (gain2 > gain1))
matchLength = repLength, offset = 0, start = ip;
} }
size_t const ml2 = searchMax(ctx, ip, iend, &offset2, maxSearches, mls);
int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)offset2+1)); /* raw approx */
int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offset+1) + 7);
- if ((ml2 >= EQUAL_READ32) && (gain2 > gain1)) {
+ if ((ml2 >= 4) && (gain2 > gain1)) {
matchLength = ml2, offset = offset2, start = ip;
continue;
} } }
if (MEM_read32(ip) == MEM_read32(repMatch)) {
/* repcode detected we should take it */
const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
- matchLength = ZSTD_count_2segments(ip+EQUAL_READ32, repMatch+EQUAL_READ32, iend, repEnd, prefixStart) + EQUAL_READ32;
+ matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
offset = offset_2; offset_2 = offset_1; offset_1 = (U32)offset; /* swap offset history */
ZSTD_storeSeq(seqStorePtr, 0, anchor, 0, matchLength-MINMATCH);
ip += matchLength;
projects / thirdparty / zstd.git / commitdiff
