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added ZSTD_DCtx_reset()

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This commit is contained in:
Yann Collet 2017-09-25 16:21:17 -07:00
parent f2a913862c
commit 52a1d1c6dc
4 changed files with 47 additions and 13 deletions
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11
doc/zstd_manual.html
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@ -649,7 +649,7 @@ size_t ZSTD_initCStream_usingCDict_advanced(ZSTD_CStream* zcs, const ZSTD_CDict*
<h3>Advanced Streaming decompression functions</h3><pre></pre><b><pre>ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem);
ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); </b>/**< same as ZSTD_initStaticDCtx() */<b>
typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e;
size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue);
size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue); </b>/* obsolete : this API will be removed in a future version */<b>
size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); </b>/**< note: no dictionary will be used if dict == NULL or dictSize < 8 */<b>
size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); </b>/**< note : ddict is referenced, it must outlive decompression session */<b>
size_t ZSTD_resetDStream(ZSTD_DStream* zds); </b>/**< re-use decompression parameters from previous init; saves dictionary loading */<b>
@ -1154,6 +1154,15 @@ size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx, const void* prefix, size_t
</p></pre><BR>
<pre><b>void ZSTD_DCtx_reset(ZSTD_DCtx* dctx); </b>/* Not ready yet ! */<b>
</b><p> Return a DCtx to clean state.
If a decompression was ongoing, any internal data not yet flushed is cancelled.
All parameters are back to default values, including sticky ones.
Dictionary (if any) is dropped.
Parameters can be modified again after a reset.
</p></pre><BR>
<a name="Chapter21"></a><h2>Block level API</h2><pre></pre>
<pre><b></b><p> Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes).

11
lib/decompress/zstd_decompress.c
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@ -2262,13 +2262,15 @@ size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t di
return ZSTD_frameHeaderSize_prefix;
}
/* note : this variant can't fail */
size_t ZSTD_initDStream(ZSTD_DStream* zds)
{
return ZSTD_initDStream_usingDict(zds, NULL, 0);
}
/* ZSTD_initDStream_usingDDict() :
* ddict will just be referenced, and must outlive decompression session */
* ddict will just be referenced, and must outlive decompression session
* this function cannot fail */
size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict)
{
size_t const initResult = ZSTD_initDStream(zds);
@ -2613,3 +2615,10 @@ size_t ZSTD_decompress_generic_simpleArgs (
*srcPos = input.pos;
return cErr;
}
void ZSTD_DCtx_reset(ZSTD_DCtx* dctx)
{
(void)ZSTD_initDStream(dctx);
dctx->format = ZSTD_f_zstd1;
dctx->maxWindowSize = ZSTD_MAXWINDOWSIZE_DEFAULT;
}

34
lib/zstd.h
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@ -750,7 +750,7 @@ ZSTDLIB_API size_t ZSTD_resetCStream(ZSTD_CStream* zcs, unsigned long long pledg
ZSTDLIB_API ZSTD_DStream* ZSTD_createDStream_advanced(ZSTD_customMem customMem);
ZSTDLIB_API ZSTD_DStream* ZSTD_initStaticDStream(void* workspace, size_t workspaceSize); /**< same as ZSTD_initStaticDCtx() */
typedef enum { DStream_p_maxWindowSize } ZSTD_DStreamParameter_e;
ZSTDLIB_API size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue);
ZSTDLIB_API size_t ZSTD_setDStreamParameter(ZSTD_DStream* zds, ZSTD_DStreamParameter_e paramType, unsigned paramValue); /* obsolete : this API will be removed in a future version */
ZSTDLIB_API size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t dictSize); /**< note: no dictionary will be used if dict == NULL or dictSize < 8 */
ZSTDLIB_API size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); /**< note : ddict is referenced, it must outlive decompression session */
ZSTDLIB_API size_t ZSTD_resetDStream(ZSTD_DStream* zds); /**< re-use decompression parameters from previous init; saves dictionary loading */
@ -920,7 +920,7 @@ ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx);
* This API is intended to replace all others experimental API.
* It can basically do all other use cases, and even new ones.
* In constrast with _advanced() variants, it stands a reasonable chance to become "stable",
* after a testing period.
* after a good testing period.
*/
/* note on naming convention :
@ -930,22 +930,34 @@ ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx);
* It feels clearer in light of potential variants :
* ZSTD_CDict_setParameter() (rather than ZSTD_setCDictParameter())
* ZSTD_CCtxParams_setParameter() (rather than ZSTD_setCCtxParamsParameter() )
* etc...
*/
/* note on enum design :
* All enum will be manually set to explicit values before reaching "stable API" status */
* All enum will be pinned to explicit values before reaching "stable API" status */
typedef enum {
/* should we have a ZSTD_f_auto ?
* for the time being, it would mean exactly the same as ZSTD_f_zstd1.
* But, in the future, if several formats are supported,
* on the compression side, it would mean "default format",
* and on the decompression side, it would mean "multi format"
* while ZSTD_f_zstd1 could be reserved to mean "accept only zstd frames".
* Another option could be to define different enums for compression and decompression.
* This question could also be kept for later, but there is also the question of pinning the enum value,
* and pinning the value `0` is especially important */
ZSTD_f_zstd1 = 0, /* Normal zstd frame format, specified in zstd_compression_format.md (default) */
ZSTD_f_zstd1_magicless, /* Variant of zstd frame format, without initial 4-bytes magic number.
* Useful to save 4 bytes per generated frame.
* Decoder will not be able to recognise this format, requiring instructions. */
ZSTD_f_zstd1_headerless, /* Variant of zstd frame format, without any frame header;
ZSTD_f_zstd1_headerless, /* Not Implemented Yet ! Complex decoder setting ! Might be removed before release */
/* Variant of zstd frame format, without any frame header;
* Other metadata, like block size or frame checksum, are still generated.
* Useful to save between 6 and ZSTD_frameHeaderSize_max bytes per generated frame.
* However, required decoding parameters will have to be saved or known by some mechanism.
* Decoder will not be able to recognise this format, requiring instructions and parameters. */
ZSTD_f_zstd1_block /* Generate a zstd compressed block, without any metadata.
ZSTD_f_zstd1_block /* Not Implemented Yet ! Might be removed before release */
/* Generate a zstd compressed block, without any metadata.
* Note that size of block content must be <= ZSTD_getBlockSize() <= ZSTD_BLOCKSIZE_MAX == 128 KB.
* See ZSTD_compressBlock() for more details.
* Resulting compressed block can be decoded with ZSTD_decompressBlock(). */
@ -1325,11 +1337,15 @@ ZSTDLIB_API size_t ZSTD_decompress_generic_simpleArgs (
const void* src, size_t srcSize, size_t* srcPos);
/*
* Also : to re-init a decoding context, use ZSTD_initDStream().
* Here for a similar API logic, we could create ZSTD_DCtx_reset().
* It would behave the same.
/*! ZSTD_DCtx_reset() :
* Return a DCtx to clean state.
* If a decompression was ongoing, any internal data not yet flushed is cancelled.
* All parameters are back to default values, including sticky ones.
* Dictionary (if any) is dropped.
* Parameters can be modified again after a reset.
*/
ZSTDLIB_API void ZSTD_DCtx_reset(ZSTD_DCtx* dctx);
/* ============================ */

4
tests/fuzzer.c
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@ -941,11 +941,11 @@ static int basicUnitTests(U32 seed, double compressibility)
}
DISPLAYLEVEL(4, "test%3i : decompress with magic-less instruction : ", testNb++);
CHECK( ZSTD_initDStream(dctx) );
ZSTD_DCtx_reset(dctx);
CHECK( ZSTD_DCtx_setFormat(dctx, ZSTD_f_zstd1_magicless) );
{ ZSTD_inBuffer in = { compressedBuffer, cSize, 0 };
ZSTD_outBuffer out = { decodedBuffer, CNBuffSize, 0 };
size_t const result = ZSTD_decompressStream(dctx, &out, &in);
size_t const result = ZSTD_decompress_generic(dctx, &out, &in);
if (result != 0) goto _output_error;
if (in.pos != in.size) goto _output_error;
if (out.pos != inputSize) goto _output_error;