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added ZSTD_initStaticCCtx()

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makes it possible to statically or externally allocate CCtx.
static CCtx will only use provided memory area,
it will never resize nor malloc.
This commit is contained in:
Yann Collet
2017-05-23 13:16:00 -07:00
parent 5ac72b417c
commit c7fe262dc9
4 changed files with 144 additions and 14 deletions
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18
doc/zstd_manual.html
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@ -423,6 +423,22 @@ size_t ZSTD_estimateDDictSize(size_t dictSize);
</b><p> Create a ZSTD compression context using external alloc and free functions
</p></pre><BR>
<pre><b>ZSTD_CCtx* ZSTD_initStaticCCtx(void* workspace, size_t workspaceSize);
</b><p> workspace: The memory area to emplace the context into.
Provided pointer must 8-bytes aligned.
It must outlive context usage.
workspaceSize: Use ZSTD_estimateCCtxSize() or ZSTD_estimateCStreamSize()
to determine how large workspace must be to support scenario.
@return : pointer to ZSTD_CCtx*, or NULL if error (size too small)
Note : zstd will never resize nor malloc() when using a static cctx.
If it needs more memory than available, it will simply error out.
Note 2 : there is no corresponding "free" function.
Since workspace was allocated externally, it must be freed externally too.
Limitation : currently not compatible with internal CDict creation, such as
ZSTD_CCtx_loadDictionary() or ZSTD_initCStream_usingDict().
</p></pre><BR>
<pre><b>typedef enum {
ZSTD_p_forceWindow, </b>/* Force back-references to remain < windowSize, even when referencing Dictionary content (default:0) */<b>
ZSTD_p_forceRawDict </b>/* Force loading dictionary in "content-only" mode (no header analysis) */<b>
@ -714,7 +730,7 @@ size_t ZSTD_CDict_loadDictionary(ZSTD_CDict* cdict, const void* dict, size_t dic
<h3>Advanced Streaming compression functions</h3><pre></pre><b><pre>ZSTD_CStream* ZSTD_createCStream_advanced(ZSTD_customMem customMem);
size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); </b>/**< pledgedSrcSize must be correct, a size of 0 means unknown. for a frame size of 0 use initCStream_advanced */<b>
size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); </b>/**< note: a dict will not be used if dict == NULL or dictSize < 8. This result in the creation of an internal CDict */<b>
size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); </b>/**< creates of an internal CDict (incompatible with static CCtx), except if dict == NULL or dictSize < 8, in which case no dict is used. */<b>
size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs, const void* dict, size_t dictSize,
ZSTD_parameters params, unsigned long long pledgedSrcSize); </b>/**< pledgedSrcSize is optional and can be 0 (meaning unknown). note: if the contentSizeFlag is set, pledgedSrcSize == 0 means the source size is actually 0 */<b>
size_t ZSTD_initCStream_usingCDict(ZSTD_CStream* zcs, const ZSTD_CDict* cdict); </b>/**< note : cdict will just be referenced, and must outlive compression session */<b>