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modified streaming decompression API

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This commit is contained in:
Yann Collet
2016-01-26 15:58:49 +01:00
parent b923f65076
commit 7b51a2948f
9 changed files with 193 additions and 171 deletions
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lib/zstd_buffered.c
+5 -12
View File
@@ -335,8 +335,6 @@ struct ZBUFF_DCtx_s {
size_t outStart;
size_t outEnd;
size_t hPos;
const char* dict;
size_t dictSize;
ZBUFF_dStage stage;
unsigned char headerBuffer[ZSTD_frameHeaderSize_max];
}; /* typedef'd to ZBUFF_DCtx within "zstd_buffered.h" */
@@ -365,19 +363,16 @@ size_t ZBUFF_freeDCtx(ZBUFF_DCtx* zbc)
/* *** Initialization *** */
size_t ZBUFF_decompressInit(ZBUFF_DCtx* zbc)
size_t ZBUFF_decompressInitDictionary(ZBUFF_DCtx* zbc, const void* dict, size_t dictSize)
{
zbc->stage = ZBUFFds_readHeader;
zbc->hPos = zbc->inPos = zbc->outStart = zbc->outEnd = zbc->dictSize = 0;
return ZSTD_resetDCtx(zbc->zc);
zbc->hPos = zbc->inPos = zbc->outStart = zbc->outEnd = 0;
return ZSTD_decompressBegin_usingDict(zbc->zc, dict, dictSize);
}
size_t ZBUFF_decompressWithDictionary(ZBUFF_DCtx* zbc, const void* src, size_t srcSize)
size_t ZBUFF_decompressInit(ZBUFF_DCtx* zbc)
{
zbc->dict = (const char*)src;
zbc->dictSize = srcSize;
return 0;
return ZBUFF_decompressInitDictionary(zbc, NULL, 0);
}
@@ -458,8 +453,6 @@ size_t ZBUFF_decompressContinue(ZBUFF_DCtx* zbc, void* dst, size_t* maxDstSizePt
if (zbc->outBuff == NULL) return ERROR(memory_allocation);
}
}
if (zbc->dictSize)
ZSTD_decompress_insertDictionary(zbc->zc, zbc->dict, zbc->dictSize);
if (zbc->hPos)
{
/* some data already loaded into headerBuffer : transfer into inBuff */
lib/zstd_buffered.h
+8 -11
View File
@@ -48,7 +48,7 @@ extern "C" {
/* ***************************************************************
* Tuning parameters
* Compiler specifics
*****************************************************************/
/*!
* ZSTD_DLL_EXPORT :
@@ -69,7 +69,7 @@ ZSTDLIB_API ZBUFF_CCtx* ZBUFF_createCCtx(void);
ZSTDLIB_API size_t ZBUFF_freeCCtx(ZBUFF_CCtx* cctx);
ZSTDLIB_API size_t ZBUFF_compressInit(ZBUFF_CCtx* cctx, int compressionLevel);
ZSTDLIB_API size_t ZBUFF_compressWithDictionary(ZBUFF_CCtx* cctx, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZBUFF_compressWithDictionary(ZBUFF_CCtx* cctx, const void* dict, size_t dictSize);
ZSTDLIB_API size_t ZBUFF_compressContinue(ZBUFF_CCtx* cctx, void* dst, size_t* maxDstSizePtr, const void* src, size_t* srcSizePtr);
ZSTDLIB_API size_t ZBUFF_compressFlush(ZBUFF_CCtx* cctx, void* dst, size_t* maxDstSizePtr);
ZSTDLIB_API size_t ZBUFF_compressEnd(ZBUFF_CCtx* cctx, void* dst, size_t* maxDstSizePtr);
@@ -119,7 +119,7 @@ ZSTDLIB_API ZBUFF_DCtx* ZBUFF_createDCtx(void);
ZSTDLIB_API size_t ZBUFF_freeDCtx(ZBUFF_DCtx* dctx);
ZSTDLIB_API size_t ZBUFF_decompressInit(ZBUFF_DCtx* dctx);
ZSTDLIB_API size_t ZBUFF_decompressWithDictionary(ZBUFF_DCtx* dctx, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZBUFF_decompressInitDictionary(ZBUFF_DCtx* dctx, const void* dict, size_t dictSize);
ZSTDLIB_API size_t ZBUFF_decompressContinue(ZBUFF_DCtx* dctx, void* dst, size_t* maxDstSizePtr, const void* src, size_t* srcSizePtr);
@@ -128,19 +128,16 @@ ZSTDLIB_API size_t ZBUFF_decompressContinue(ZBUFF_DCtx* dctx, void* dst, size_t*
*
* A ZBUFF_DCtx object is required to track streaming operation.
* Use ZBUFF_createDCtx() and ZBUFF_freeDCtx() to create/release resources.
* Use ZBUFF_decompressInit() to start a new decompression operation.
* ZBUFF_DCtx objects can be reused multiple times.
*
* Optionally, a reference to a static dictionary can be set, using ZBUFF_decompressWithDictionary()
* It must be the same content as the one set during compression phase.
* Dictionary content must remain accessible during the decompression process.
* Use ZBUFF_decompressInit() to start a new decompression operation,
* or ZBUFF_decompressInitDictionary() if decompression requires a dictionary.
* Note that ZBUFF_DCtx objects can be reused multiple times.
*
* Use ZBUFF_decompressContinue() repetitively to consume your input.
* *srcSizePtr and *maxDstSizePtr can be any size.
* The function will report how many bytes were read or written by modifying *srcSizePtr and *maxDstSizePtr.
* Note that it may not consume the entire input, in which case it's up to the caller to present remaining input again.
* The content of dst will be overwritten (up to *maxDstSizePtr) at each function call, so save its content if it matters or change dst.
* @return : a hint to preferred nb of bytes to use as input for next function call (it's only a hint, to improve latency)
* @return : a hint to preferred nb of bytes to use as input for next function call (it's only a hint, to help latency)
* or 0 when a frame is completely decoded
* or an error code, which can be tested using ZBUFF_isError().
*
@@ -157,7 +154,7 @@ ZSTDLIB_API unsigned ZBUFF_isError(size_t errorCode);
ZSTDLIB_API const char* ZBUFF_getErrorName(size_t errorCode);
/** The below functions provide recommended buffer sizes for Compression or Decompression operations.
* These sizes are not compulsory, they just tend to offer better latency */
* These sizes are just hints, and tend to offer better latency */
ZSTDLIB_API size_t ZBUFF_recommendedCInSize(void);
ZSTDLIB_API size_t ZBUFF_recommendedCOutSize(void);
ZSTDLIB_API size_t ZBUFF_recommendedDInSize(void);
lib/zstd_compress.c
+46 -42
View File
@@ -225,6 +225,42 @@ static size_t ZSTD_resetCCtx_advanced (ZSTD_CCtx* zc,
}
/*! ZSTD_copyCCtx
* Duplicate an existing context @srcCCtx into another one @dstCCtx.
* Only works during stage 0 (i.e. before first call to ZSTD_compressContinue())
* @return : 0, or an error code */
size_t ZSTD_copyCCtx(ZSTD_CCtx* dstCCtx, const ZSTD_CCtx* srcCCtx)
{
const U32 contentLog = (srcCCtx->params.strategy == ZSTD_fast) ? 1 : srcCCtx->params.contentLog;
const size_t tableSpace = ((1 << contentLog) + (1 << srcCCtx->params.hashLog)) * sizeof(U32);
if (srcCCtx->stage!=0) return ERROR(stage_wrong);
ZSTD_resetCCtx_advanced(dstCCtx, srcCCtx->params);
/* copy tables */
memcpy(dstCCtx->hashTable, srcCCtx->hashTable, tableSpace);
/* copy frame header */
dstCCtx->hbSize = srcCCtx->hbSize;
memcpy(dstCCtx->headerBuffer , srcCCtx->headerBuffer, srcCCtx->hbSize);
/* copy dictionary pointers */
dstCCtx->nextToUpdate= srcCCtx->nextToUpdate;
dstCCtx->nextSrc = srcCCtx->nextSrc;
dstCCtx->base = srcCCtx->base;
dstCCtx->dictBase = srcCCtx->dictBase;
dstCCtx->dictLimit = srcCCtx->dictLimit;
dstCCtx->lowLimit = srcCCtx->lowLimit;
dstCCtx->flagHufTable = srcCCtx->flagHufTable;
if (dstCCtx->flagHufTable)
memcpy(dstCCtx->hufTable, srcCCtx->hufTable, 256*4);
return 0;
}
/** ZSTD_reduceIndex
* rescale indexes to avoid future overflow (indexes are U32) */
static void ZSTD_reduceIndex (ZSTD_CCtx* zc,
@@ -2133,49 +2169,17 @@ static size_t ZSTD_loadDictEntropyStats(ZSTD_CCtx* zc, const void* dict, size_t
size_t ZSTD_compress_insertDictionary(ZSTD_CCtx* zc, const void* dict, size_t dictSize)
{
U32 magic = MEM_readLE32(dict);
U32 eSize;
if (magic != ZSTD_DICT_MAGIC)
return ZSTD_loadDictionaryContent(zc, dict, dictSize);
eSize = ZSTD_loadDictEntropyStats(zc, (const char*)dict+4, dictSize-4) + 4;
if (ZSTD_isError(eSize)) return eSize;
return ZSTD_loadDictionaryContent(zc, (const char*)dict+eSize, dictSize-eSize);
}
/*! ZSTD_duplicateCCtx
* Duplicate an existing context @srcCCtx into another one @dstCCtx.
* Only works during stage 0 (i.e. before first call to ZSTD_compressContinue())
* @return : 0, or an error code */
size_t ZSTD_duplicateCCtx(ZSTD_CCtx* dstCCtx, const ZSTD_CCtx* srcCCtx)
{
const U32 contentLog = (srcCCtx->params.strategy == ZSTD_fast) ? 1 : srcCCtx->params.contentLog;
const size_t tableSpace = ((1 << contentLog) + (1 << srcCCtx->params.hashLog)) * sizeof(U32);
if (srcCCtx->stage!=0) return ERROR(stage_wrong);
ZSTD_resetCCtx_advanced(dstCCtx, srcCCtx->params);
/* copy tables */
memcpy(dstCCtx->hashTable, srcCCtx->hashTable, tableSpace);
/* copy frame header */
dstCCtx->hbSize = srcCCtx->hbSize;
memcpy(dstCCtx->headerBuffer , srcCCtx->headerBuffer, srcCCtx->hbSize);
/* copy dictionary pointers */
dstCCtx->nextToUpdate= srcCCtx->nextToUpdate;
dstCCtx->nextSrc = srcCCtx->nextSrc;
dstCCtx->base = srcCCtx->base;
dstCCtx->dictBase = srcCCtx->dictBase;
dstCCtx->dictLimit = srcCCtx->dictLimit;
dstCCtx->lowLimit = srcCCtx->lowLimit;
dstCCtx->flagHufTable = srcCCtx->flagHufTable;
if (dstCCtx->flagHufTable)
memcpy(dstCCtx->hufTable, srcCCtx->hufTable, 256*4);
if (dict && dictSize)
{
U32 magic = MEM_readLE32(dict);
size_t eSize;
if (magic != ZSTD_DICT_MAGIC)
return ZSTD_loadDictionaryContent(zc, dict, dictSize);
eSize = ZSTD_loadDictEntropyStats(zc, (const char*)dict+4, dictSize-4) + 4;
if (ZSTD_isError(eSize)) return eSize;
return ZSTD_loadDictionaryContent(zc, (const char*)dict+eSize, dictSize-eSize);
}
return 0;
}
lib/zstd_decompress.c
+67 -47
View File
@@ -136,6 +136,7 @@ struct ZSTD_DCtx_s
ZSTD_parameters params;
blockType_t bType;
ZSTD_dStage stage;
U32 flagHufTable;
const BYTE* litPtr;
size_t litBufSize;
size_t litSize;
@@ -143,7 +144,7 @@ struct ZSTD_DCtx_s
BYTE headerBuffer[ZSTD_frameHeaderSize_max];
}; /* typedef'd to ZSTD_DCtx within "zstd_static.h" */
size_t ZSTD_resetDCtx(ZSTD_DCtx* dctx)
size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx)
{
dctx->expected = ZSTD_frameHeaderSize_min;
dctx->stage = ZSTDds_getFrameHeaderSize;
@@ -152,6 +153,7 @@ size_t ZSTD_resetDCtx(ZSTD_DCtx* dctx)
dctx->vBase = NULL;
dctx->dictEnd = NULL;
dctx->hufTableX4[0] = HufLog;
dctx->flagHufTable = 0;
return 0;
}
@@ -159,7 +161,7 @@ ZSTD_DCtx* ZSTD_createDCtx(void)
{
ZSTD_DCtx* dctx = (ZSTD_DCtx*)malloc(sizeof(ZSTD_DCtx));
if (dctx==NULL) return NULL;
ZSTD_resetDCtx(dctx);
ZSTD_decompressBegin(dctx);
return dctx;
}
@@ -169,6 +171,12 @@ size_t ZSTD_freeDCtx(ZSTD_DCtx* dctx)
return 0;
}
void ZSTD_copyDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx)
{
memcpy(dstDCtx, srcDCtx,
sizeof(ZSTD_DCtx) - (BLOCKSIZE+WILDCOPY_OVERLENGTH + ZSTD_frameHeaderSize_max)); /* no need to copy workspace */
}
/* *************************************************************
* Decompression section
@@ -342,6 +350,8 @@ size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
U32 lhSize = ((istart[0]) >> 4) & 3;
if (lhSize != 1) /* only case supported for now : small litSize, single stream */
return ERROR(corruption_detected);
if (!dctx->flagHufTable)
return ERROR(dictionary_corrupted);
/* 2 - 2 - 10 - 10 */
lhSize=3;
@@ -631,14 +641,12 @@ FORCE_INLINE size_t ZSTD_execSequence(BYTE* op,
*litPtr = litEnd; /* update for next sequence */
/* copy Match */
if (sequence.offset > (size_t)(oLitEnd - base))
{
if (sequence.offset > (size_t)(oLitEnd - base)) {
/* offset beyond prefix */
if (sequence.offset > (size_t)(oLitEnd - vBase))
return ERROR(corruption_detected);
match = dictEnd - (base-match);
if (match + sequence.matchLength <= dictEnd)
{
if (match + sequence.matchLength <= dictEnd) {
memmove(oLitEnd, match, sequence.matchLength);
return sequenceLength;
}
@@ -653,8 +661,7 @@ FORCE_INLINE size_t ZSTD_execSequence(BYTE* op,
}
/* match within prefix */
if (sequence.offset < 8)
{
if (sequence.offset < 8) {
/* close range match, overlap */
const int sub2 = dec64table[sequence.offset];
op[0] = match[0];
@@ -665,24 +672,20 @@ FORCE_INLINE size_t ZSTD_execSequence(BYTE* op,
ZSTD_copy4(op+4, match);
match -= sub2;
}
else
{
else {
ZSTD_copy8(op, match);
}
op += 8; match += 8;
if (oMatchEnd > oend-12)
{
if (op < oend_8)
{
if (oMatchEnd > oend-12) {
if (op < oend_8) {
ZSTD_wildcopy(op, match, oend_8 - op);
match += oend_8 - op;
op = oend_8;
}
while (op < oMatchEnd) *op++ = *match++;
}
else
{
else {
ZSTD_wildcopy(op, match, sequence.matchLength-8); /* works even if matchLength < 8 */
}
return sequenceLength;
@@ -735,8 +738,7 @@ static size_t ZSTD_decompressSequences(
FSE_initDState(&(seqState.stateOffb), &(seqState.DStream), DTableOffb);
FSE_initDState(&(seqState.stateML), &(seqState.DStream), DTableML);
for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; )
{
for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; ) {
size_t oneSeqSize;
nbSeq--;
ZSTD_decodeSequence(&sequence, &seqState);
@@ -764,8 +766,7 @@ static size_t ZSTD_decompressSequences(
static void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst)
{
if (dst != dctx->previousDstEnd) /* not contiguous */
{
if (dst != dctx->previousDstEnd) { /* not contiguous */
dctx->dictEnd = dctx->previousDstEnd;
dctx->vBase = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->base));
dctx->base = dst;
@@ -800,10 +801,11 @@ size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx,
}
size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
/*! ZSTD_decompress_continueDCtx
* dctx must have been properly initialized */
static size_t ZSTD_decompress_continueDCtx(ZSTD_DCtx* dctx,
void* dst, size_t maxDstSize,
const void* src, size_t srcSize,
const void* dict, size_t dictSize)
const void* src, size_t srcSize)
{
const BYTE* ip = (const BYTE*)src;
const BYTE* iend = ip + srcSize;
@@ -813,21 +815,6 @@ size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
size_t remainingSize = srcSize;
blockProperties_t blockProperties;
/* init */
ZSTD_resetDCtx(dctx);
if (dict)
{
size_t errorCode = ZSTD_decompress_insertDictionary(dctx, dict, dictSize);
if (ZSTD_isError(errorCode)) return ERROR(dictionary_corrupted);
dctx->dictEnd = dctx->previousDstEnd;
dctx->vBase = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->base));
dctx->base = dst;
}
else
{
dctx->vBase = dctx->base = dctx->dictEnd = dst;
}
/* Frame Header */
{
size_t frameHeaderSize;
@@ -888,6 +875,27 @@ size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
}
size_t ZSTD_decompress_usingPreparedDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* refDCtx,
void* dst, size_t maxDstSize,
const void* src, size_t srcSize)
{
ZSTD_copyDCtx(dctx, refDCtx);
ZSTD_checkContinuity(dctx, dst);
return ZSTD_decompress_continueDCtx(dctx, dst, maxDstSize, src, srcSize);
}
size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
void* dst, size_t maxDstSize,
const void* src, size_t srcSize,
const void* dict, size_t dictSize)
{
ZSTD_decompressBegin_usingDict(dctx, dict, dictSize);
ZSTD_checkContinuity(dctx, dst);
return ZSTD_decompress_continueDCtx(dctx, dst, maxDstSize, src, srcSize);
}
size_t ZSTD_decompressDCtx(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, const void* src, size_t srcSize)
{
return ZSTD_decompress_usingDict(dctx, dst, maxDstSize, src, srcSize, NULL, 0);
@@ -933,8 +941,7 @@ size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, co
dctx->headerSize = ZSTD_decodeFrameHeader_Part1(dctx, src, ZSTD_frameHeaderSize_min);
if (ZSTD_isError(dctx->headerSize)) return dctx->headerSize;
memcpy(dctx->headerBuffer, src, ZSTD_frameHeaderSize_min);
if (dctx->headerSize > ZSTD_frameHeaderSize_min)
{
if (dctx->headerSize > ZSTD_frameHeaderSize_min) {
dctx->expected = dctx->headerSize - ZSTD_frameHeaderSize_min;
dctx->stage = ZSTDds_decodeFrameHeader;
return 0;
@@ -958,13 +965,11 @@ size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, co
blockProperties_t bp;
size_t blockSize = ZSTD_getcBlockSize(src, ZSTD_blockHeaderSize, &bp);
if (ZSTD_isError(blockSize)) return blockSize;
if (bp.blockType == bt_end)
{
if (bp.blockType == bt_end) {
dctx->expected = 0;
dctx->stage = ZSTDds_getFrameHeaderSize;
}
else
{
else {
dctx->expected = blockSize;
dctx->bType = bp.blockType;
dctx->stage = ZSTDds_decompressBlock;
@@ -990,7 +995,7 @@ size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, co
rSize = 0;
break;
default:
return ERROR(GENERIC);
return ERROR(GENERIC); /* impossible */
}
dctx->stage = ZSTDds_decodeBlockHeader;
dctx->expected = ZSTD_blockHeaderSize;
@@ -1011,15 +1016,15 @@ static void ZSTD_refDictContent(ZSTD_DCtx* dctx, const void* dict, size_t dictSi
dctx->previousDstEnd = (const char*)dict + dictSize;
}
static size_t ZSTD_loadEntropy(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
{
size_t hSize = HUF_readDTableX4(dctx->hufTableX4, dict, dictSize);
if (HUF_isError(hSize)) return ERROR(dictionary_corrupted);
dctx->flagHufTable = 1;
return hSize;
}
size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
static size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
{
size_t eSize;
U32 magic = MEM_readLE32(dict);
@@ -1042,3 +1047,18 @@ size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* dctx, const void* dict, size_
return 0;
}
size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize)
{
size_t errorCode;
errorCode = ZSTD_decompressBegin(dctx);
if (ZSTD_isError(errorCode)) return errorCode;
if (dict && dictSize) {
errorCode = ZSTD_decompress_insertDictionary(dctx, dict, dictSize);
if (ZSTD_isError(errorCode)) return ERROR(dictionary_corrupted);
}
return 0;
}
lib/zstd_static.h
+35 -24
View File
@@ -92,7 +92,7 @@ ZSTDLIB_API ZSTD_parameters ZSTD_getParams(int compressionLevel, U64 srcSizeHint
ZSTDLIB_API void ZSTD_validateParams(ZSTD_parameters* params);
/** ZSTD_compress_usingDict
* Same as ZSTD_compressCCtx(), using a Dictionary content as prefix
* Same as ZSTD_compressCCtx(), loading a Dictionary content.
* Note : dict can be NULL, in which case, it's equivalent to ZSTD_compressCCtx() */
ZSTDLIB_API size_t ZSTD_compress_usingDict(ZSTD_CCtx* ctx,
void* dst, size_t maxDstSize,
@@ -108,14 +108,24 @@ ZSTDLIB_API size_t ZSTD_compress_advanced (ZSTD_CCtx* ctx,
const void* dict,size_t dictSize,
ZSTD_parameters params);
/** ZSTD_decompress_usingDict
/*! ZSTD_decompress_usingDict
* Same as ZSTD_decompressDCtx, using a Dictionary content as prefix
* Note : dict can be NULL, in which case, it's equivalent to ZSTD_decompressDCtx() */
ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* ctx,
ZSTDLIB_API size_t ZSTD_decompress_usingDict(ZSTD_DCtx* dctx,
void* dst, size_t maxDstSize,
const void* src, size_t srcSize,
const void* dict,size_t dictSize);
/*! ZSTD_decompress_usingPreparedDCtx
* Same as ZSTD_decompress_usingDict, but using a reference context preparedDCtx, where dictionary has already been loaded into.
* It avoids reloading the dictionary each time.
* preparedDCtx must have been properly initialized using ZSTD_compressBegin_usingDict().
* Requires 2 contexts : 1 for reference, which will not be modified, and 1 to run the decompression operation */
ZSTDLIB_API size_t ZSTD_decompress_usingPreparedDCtx(
ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx,
void* dst, size_t maxDstSize,
const void* src, size_t srcSize);
/* **************************************
* Streaming functions (direct mode)
@@ -127,7 +137,7 @@ ZSTDLIB_API size_t ZSTD_compressBegin_usingDict(ZSTD_CCtx* cctx, const void* dic
ZSTDLIB_API size_t ZSTD_compressBegin_advanced(ZSTD_CCtx* ctx, ZSTD_parameters params);
ZSTDLIB_API size_t ZSTD_compress_insertDictionary(ZSTD_CCtx* ctx, const void* dict, size_t dictSize);
ZSTDLIB_API size_t ZSTD_duplicateCCtx(ZSTD_CCtx* dstCCtx, const ZSTD_CCtx* srcCCtx);
ZSTDLIB_API size_t ZSTD_copyCCtx(ZSTD_CCtx* dstCCtx, const ZSTD_CCtx* srcCCtx);
ZSTDLIB_API size_t ZSTD_compressContinue(ZSTD_CCtx* cctx, void* dst, size_t maxDstSize, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t maxDstSize);
@@ -164,9 +174,11 @@ ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t maxDstSiz
*/
ZSTDLIB_API size_t ZSTD_resetDCtx(ZSTD_DCtx* dctx);
ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx);
ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
ZSTDLIB_API void ZSTD_copyDCtx(ZSTD_DCtx* dstDCtx, const ZSTD_DCtx* srcDCtx);
ZSTDLIB_API size_t ZSTD_getFrameParams(ZSTD_parameters* params, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZSTD_decompress_insertDictionary(ZSTD_DCtx* ctx, const void* src, size_t srcSize);
ZSTDLIB_API size_t ZSTD_nextSrcSizeToDecompress(ZSTD_DCtx* dctx);
ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, const void* src, size_t srcSize);
@@ -176,20 +188,19 @@ ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t ma
A ZSTD_DCtx object is required to track streaming operations.
Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it.
A ZSTD_DCtx object can be re-used multiple times. Use ZSTD_resetDCtx() to return to fresh status.
A ZSTD_DCtx object can be re-used multiple times.
First operation is to retrieve frame parameters, using ZSTD_getFrameParams().
This function doesn't consume its input. It needs enough input data to properly decode the frame header.
First typical operation is to retrieve frame parameters, using ZSTD_getFrameParams().
This operation is independent, and just needs enough input data to properly decode the frame header.
Objective is to retrieve *params.windowlog, to know minimum amount of memory required during decoding.
Result : 0 when successful, it means the ZSTD_parameters structure has been filled.
>0 : means there is not enough data into src. Provides the expected size to successfully decode header.
errorCode, which can be tested using ZSTD_isError() (For example, if it's not a ZSTD header)
errorCode, which can be tested using ZSTD_isError()
Then, you can optionally insert a dictionary.
This operation must mimic the compressor behavior, otherwise decompression will fail or be corrupted.
Start decompression, with ZSTD_decompressBegin() or ZSTD_decompressBegin_usingDict()
Alternatively, you can copy a prepared context, using ZSTD_copyDCtx()
Then it's possible to start decompression.
Use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively.
Then use ZSTD_nextSrcSizeToDecompress() and ZSTD_decompressContinue() alternatively.
ZSTD_nextSrcSizeToDecompress() tells how much bytes to provide as 'srcSize' to ZSTD_decompressContinue().
ZSTD_decompressContinue() requires this exact amount of bytes, or it will fail.
ZSTD_decompressContinue() needs previous data blocks during decompression, up to (1 << windowlog).
@@ -206,23 +217,23 @@ ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t ma
/* **************************************
* Block functions
****************************************/
/*!Block functions produce and decode raw zstd blocks, without frame metadata.
It saves associated header sizes.
But user will have to save and regenerate fields required to regenerate data, such as block sizes.
Frame headers won't be generated.
User will have to save and regenerate fields required to regenerate data, such as block sizes.
A few rules to respect :
- Uncompressed block size must be <= 128 KB
- Compressing or decompressing require a context structure
- Compressing or decompressing requires a context structure
+ Use ZSTD_createXCtx() to create them
- It is necessary to init context before starting
+ compression : ZSTD_compressBegin(), which allows selection of compression level or parameters
+ decompression : ZSTD_resetDCtx()
+ If you compress multiple blocks without resetting, next blocks will create references to previous ones
- Dictionary can optionally be inserted, using ZSTD_de/compress_insertDictionary()
+ compression : ZSTD_compressBegin()
+ decompression : ZSTD_decompressBegin()
+ variants _usingDict() are also allowed
+ copyXCtx() works too
- When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero.
+ User must test for such outcome and be able to deal with uncompressed data
+ ZSTD_decompressBlock() doesn't accept uncompressed data as input
In which case, nothing is produced into `dst`.
+ User must test for such outcome and deal directly with uncompressed data
+ ZSTD_decompressBlock() doesn't accept uncompressed data as input !!
*/
size_t ZSTD_compressBlock (ZSTD_CCtx* cctx, void* dst, size_t maxDstSize, const void* src, size_t srcSize);