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Improved code comments for block functions

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Yann Collet
2017-04-18 03:17:44 -07:00
parent 4f818182b8
commit af4f45b682
1 changed files with 10 additions and 9 deletions
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lib/zstd.h
+10 -9
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@@ -754,19 +754,20 @@ ZSTDLIB_API ZSTD_nextInputType_e ZSTD_nextInputType(ZSTD_DCtx* dctx);
- Compressing and decompressing require a context structure - Compressing and decompressing require a context structure
+ Use ZSTD_createCCtx() and ZSTD_createDCtx() + Use ZSTD_createCCtx() and ZSTD_createDCtx()
- It is necessary to init context before starting - It is necessary to init context before starting
+ compression : ZSTD_compressBegin() + compression : any ZSTD_compressBegin*() variant, including with dictionary
+ decompression : ZSTD_decompressBegin() + decompression : any ZSTD_decompressBegin*() variant, including with dictionary
+ variants _usingDict() are also allowed + copyCCtx() and copyDCtx() can be used too
+ copyCCtx() and copyDCtx() work too - Block size is limited, it must be <= ZSTD_getBlockSizeMax() <= ZSTD_BLOCKSIZE_ABSOLUTEMAX
- Block size is limited, it must be <= ZSTD_getBlockSizeMax() + If input is larger than a block size, it's necessary to split input data into multiple blocks
+ If you need to compress more, cut data into multiple blocks + For inputs larger than a single block size, consider using the regular ZSTD_compress() instead.
+ Consider using the regular ZSTD_compress() instead, as frame metadata costs become negligible when source size is large. Frame metadata is not that costly, and quickly becomes negligible as source size grows larger.
- When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero. - When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero.
In which case, nothing is produced into `dst`. In which case, nothing is produced into `dst`.
+ User must test for such outcome and deal directly with uncompressed data + User must test for such outcome and deal directly with uncompressed data
+ ZSTD_decompressBlock() doesn't accept uncompressed data as input !!! + ZSTD_decompressBlock() doesn't accept uncompressed data as input !!!
+ In case of multiple successive blocks, decoder must be informed of uncompressed block existence to follow proper history. + In case of multiple successive blocks, should some of them be uncompressed,
Use ZSTD_insertBlock() in such a case. decoder must be informed of their existence in order to follow proper history.
Use ZSTD_insertBlock() for such a case.
*/ */
#define ZSTD_BLOCKSIZE_ABSOLUTEMAX (128 * 1024) /* define, for static allocation */ #define ZSTD_BLOCKSIZE_ABSOLUTEMAX (128 * 1024) /* define, for static allocation */