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ZSTD_estimateCStreamSize_advanced()

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This commit is contained in:
Yann Collet 2017-06-26 16:02:25 -07:00
parent 31af8290d1
commit 0c9a915a28
5 changed files with 21 additions and 9 deletions
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10
doc/zstd_manual.html
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@ -414,14 +414,18 @@ size_t ZSTD_estimateDCtxSize(void);
of a future {D,C}Ctx, before its creation.
The objective is to guide decision before allocation.
ZSTD_estimateCCtxSize() will consider src size to be arbitrarily "large".
If srcSize is known to be small, ZSTD_estimateCCtxSize_advanced() will provide a better (smaller) estimation.
If srcSize is known to be small, ZSTD_estimateCCtxSize_advanced() can provide a tighter estimation.
ZSTD_estimateCCtxSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
Note : CCtx estimation is only correct for single-threaded compression
</p></pre><BR>
<pre><b>size_t ZSTD_estimateCStreamSize(ZSTD_compressionParameters cParams);
<pre><b>size_t ZSTD_estimateCStreamSize(int compressionLevel);
size_t ZSTD_estimateCStreamSize_advanced(ZSTD_compressionParameters cParams);
size_t ZSTD_estimateDStreamSize(ZSTD_frameHeader fHeader);
</b><p> Note : if streaming is init with function ZSTD_init?Stream_usingDict(),
</b><p> ZSTD_estimateCStreamSize() will consider src size to be arbitrarily "large".
If srcSize is known to be small, ZSTD_estimateCStreamSize_advanced() can provide a tighter estimation.
ZSTD_estimateCStreamSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
Note : if streaming is init with function ZSTD_init?Stream_usingDict(),
an internal ?Dict will be created, which size is not estimated here.
In this case, get total size by adding ZSTD_estimate?DictSize
</p></pre><BR>

7
lib/compress/zstd_compress.c
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@ -564,7 +564,7 @@ size_t ZSTD_estimateCCtxSize(int compressionLevel)
return ZSTD_estimateCCtxSize_advanced(cParams);
}
size_t ZSTD_estimateCStreamSize(ZSTD_compressionParameters cParams)
size_t ZSTD_estimateCStreamSize_advanced(ZSTD_compressionParameters cParams)
{
size_t const CCtxSize = ZSTD_estimateCCtxSize_advanced(cParams);
size_t const blockSize = MIN(ZSTD_BLOCKSIZE_MAX, (size_t)1 << cParams.windowLog);
@ -575,6 +575,11 @@ size_t ZSTD_estimateCStreamSize(ZSTD_compressionParameters cParams)
return CCtxSize + streamingSize;
}
size_t ZSTD_estimateCStreamSize(int compressionLevel) {
ZSTD_compressionParameters const cParams = ZSTD_getCParams(compressionLevel, 0, 0);
return ZSTD_estimateCStreamSize_advanced(cParams);
}
static U32 ZSTD_equivalentParams(ZSTD_compressionParameters cParams1,
ZSTD_compressionParameters cParams2)

8
lib/zstd.h
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@ -498,7 +498,7 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
* of a future {D,C}Ctx, before its creation.
* The objective is to guide decision before allocation.
* ZSTD_estimateCCtxSize() will consider src size to be arbitrarily "large".
* If srcSize is known to be small, ZSTD_estimateCCtxSize_advanced() will provide a better (smaller) estimation.
* If srcSize is known to be small, ZSTD_estimateCCtxSize_advanced() can provide a tighter estimation.
* ZSTD_estimateCCtxSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
* Note : CCtx estimation is only correct for single-threaded compression */
ZSTDLIB_API size_t ZSTD_estimateCCtxSize(int compressionLevel);
@ -506,10 +506,14 @@ ZSTDLIB_API size_t ZSTD_estimateCCtxSize_advanced(ZSTD_compressionParameters cPa
ZSTDLIB_API size_t ZSTD_estimateDCtxSize(void);
/*! ZSTD_estimate?StreamSize() :
* ZSTD_estimateCStreamSize() will consider src size to be arbitrarily "large".
* If srcSize is known to be small, ZSTD_estimateCStreamSize_advanced() can provide a tighter estimation.
* ZSTD_estimateCStreamSize_advanced() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel.
* Note : if streaming is init with function ZSTD_init?Stream_usingDict(),
* an internal ?Dict will be created, which size is not estimated here.
* In this case, get total size by adding ZSTD_estimate?DictSize */
ZSTDLIB_API size_t ZSTD_estimateCStreamSize(ZSTD_compressionParameters cParams);
ZSTDLIB_API size_t ZSTD_estimateCStreamSize(int compressionLevel);
ZSTDLIB_API size_t ZSTD_estimateCStreamSize_advanced(ZSTD_compressionParameters cParams);
ZSTDLIB_API size_t ZSTD_estimateDStreamSize(ZSTD_frameHeader fHeader);
/*! ZSTD_estimate?DictSize() :

3
tests/fuzzer.c
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@ -193,8 +193,7 @@ static int basicUnitTests(U32 seed, double compressibility)
/* Static CCtx tests */
#define STATIC_CCTX_LEVEL 3
DISPLAYLEVEL(4, "test%3i : create static CCtx for level %u :", testNb++, STATIC_CCTX_LEVEL);
{ ZSTD_compressionParameters const cParams = ZSTD_getCParams(STATIC_CCTX_LEVEL, 0, 0);
size_t const staticCCtxSize = ZSTD_estimateCStreamSize(cParams);
{ size_t const staticCCtxSize = ZSTD_estimateCStreamSize(STATIC_CCTX_LEVEL);
void* const staticCCtxBuffer = malloc(staticCCtxSize);
size_t const staticDCtxSize = ZSTD_estimateDCtxSize();
void* const staticDCtxBuffer = malloc(staticDCtxSize);

2
tests/zstreamtest.c
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@ -210,7 +210,7 @@ static int basicUnitTests(U32 seed, double compressibility, ZSTD_customMem custo
/* context size functions */
DISPLAYLEVEL(3, "test%3i : estimate CStream size : ", testNb++);
{ ZSTD_compressionParameters const cParams = ZSTD_getCParams(1, CNBufferSize, dictSize);
size_t const s = ZSTD_estimateCStreamSize(cParams)
size_t const s = ZSTD_estimateCStreamSize_advanced(cParams)
/* uses ZSTD_initCStream_usingDict() */
+ ZSTD_estimateCDictSize(cParams, dictSize, 0);
if (ZSTD_isError(s)) goto _output_error;