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