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author | W. Felix Handte <w@felixhandte.com> | 2018-05-03 03:29:07 (GMT) |
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committer | W. Felix Handte <w@felixhandte.com> | 2018-05-03 04:03:20 (GMT) |
commit | 5406c2e479f5bb2b594a43e74e28719f4640450f (patch) | |
tree | 7f35d59a31636f14a4c26c41675acbb33890ebbd /lib/lz4.h | |
parent | c32e0319a5a8319599f0f3d1a510431bdaafbdb1 (diff) | |
download | lz4-5406c2e479f5bb2b594a43e74e28719f4640450f.zip lz4-5406c2e479f5bb2b594a43e74e28719f4640450f.tar.gz lz4-5406c2e479f5bb2b594a43e74e28719f4640450f.tar.bz2 |
Only Reset the LZ4 Stream when Init'ing a Streaming Block
Diffstat (limited to 'lib/lz4.h')
-rw-r--r-- | lib/lz4.h | 24 |
1 files changed, 19 insertions, 5 deletions
@@ -358,6 +358,15 @@ LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* src, char* dst, int or #ifdef LZ4_STATIC_LINKING_ONLY /*! LZ4_resetStream_fast() : + * Use this, like LZ4_resetStream(), to prepare a context for a new chain of + * calls to a streaming API (e.g., LZ4_compress_fast_continue()). + * + * Note: + * Using this in advance of a non- streaming-compression function is redundant, + * and potentially bad for performance, since they all perform their own custom + * reset internally. + * + * Differences from LZ4_resetStream(): * When an LZ4_stream_t is known to be in a internally coherent state, * it can often be prepared for a new compression with almost no work, only * sometimes falling back to the full, expensive reset that is always required @@ -367,13 +376,17 @@ LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* src, char* dst, int or * LZ4_streams are guaranteed to be in a valid state when: * - returned from LZ4_createStream() * - reset by LZ4_resetStream() - * - memset(stream, 0, sizeof(LZ4_stream_t)) + * - memset(stream, 0, sizeof(LZ4_stream_t)), though this is discouraged * - the stream was in a valid state and was reset by LZ4_resetStream_fast() * - the stream was in a valid state and was then used in any compression call * that returned success * - the stream was in an indeterminate state and was used in a compression - * call that fully reset the state (LZ4_compress_fast_extState()) and that - * returned success + * call that fully reset the state (e.g., LZ4_compress_fast_extState()) and + * that returned success + * + * When a stream isn't known to be in a valid state, it is not safe to pass to + * any fastReset or streaming function. It must first be cleansed by the full + * LZ4_resetStream(). */ LZ4LIB_API void LZ4_resetStream_fast (LZ4_stream_t* streamPtr); @@ -384,8 +397,9 @@ LZ4LIB_API void LZ4_resetStream_fast (LZ4_stream_t* streamPtr); * to call if the state buffer is known to be correctly initialized already * (see above comment on LZ4_resetStream_fast() for a definition of "correctly * initialized"). From a high level, the difference is that this function - * initializes the provided state with a call to LZ4_resetStream_fast() while - * LZ4_compress_fast_extState() starts with a call to LZ4_resetStream(). + * initializes the provided state with a call to something like + * LZ4_resetStream_fast() while LZ4_compress_fast_extState() starts with a + * call to LZ4_resetStream(). */ LZ4LIB_API int LZ4_compress_fast_extState_fastReset (void* state, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration); |