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[zstd] Add note about empty ZSTD_CDict

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Nick Terrell
2018-08-23 17:48:06 -07:00
committed by Nick Terrell
parent 924944e471
commit 5ee5e71be3
1 changed files with 5 additions and 2 deletions
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lib/zstd.h
+5 -2
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@@ -211,7 +211,8 @@ typedef struct ZSTD_CDict_s ZSTD_CDict;
* When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once. * When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
* ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay. * ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
* ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only. * ZSTD_CDict can be created once and shared by multiple threads concurrently, since its usage is read-only.
* `dictBuffer` can be released after ZSTD_CDict creation, since its content is copied within CDict */ * `dictBuffer` can be released after ZSTD_CDict creation, since its content is copied within CDict
* Note : A ZSTD_CDict can be created with an empty dictionary, but it is inefficient for small data. */
ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize, ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize,
int compressionLevel); int compressionLevel);
@@ -223,7 +224,9 @@ ZSTDLIB_API size_t ZSTD_freeCDict(ZSTD_CDict* CDict);
* Compression using a digested Dictionary. * Compression using a digested Dictionary.
* Faster startup than ZSTD_compress_usingDict(), recommended when same dictionary is used multiple times. * Faster startup than ZSTD_compress_usingDict(), recommended when same dictionary is used multiple times.
* Note that compression level is decided during dictionary creation. * Note that compression level is decided during dictionary creation.
* Frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no) */ * Frame parameters are hardcoded (dictID=yes, contentSize=yes, checksum=no)
* Note : ZSTD_compress_usingCDict() can be used with a ZSTD_CDict created from an empty dictionary.
* But it is inefficient for small data, and it is recommended to use ZSTD_compressCCtx(). */
ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx, ZSTDLIB_API size_t ZSTD_compress_usingCDict(ZSTD_CCtx* cctx,
void* dst, size_t dstCapacity, void* dst, size_t dstCapacity,
const void* src, size_t srcSize, const void* src, size_t srcSize,