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author | Yann Collet <cyan@fb.com> | 2017-04-09 08:41:36 (GMT) |
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committer | Yann Collet <cyan@fb.com> | 2017-04-09 08:41:36 (GMT) |
commit | e2c9b19122a19fa8a46a253e4ce556a5b75fa8b1 (patch) | |
tree | c713ab373bca1e02a55036432a90fe8782e31197 /lib | |
parent | 7eecd32c079cdf1afda8c00bba83dd3a1fee3f62 (diff) | |
download | lz4-e2c9b19122a19fa8a46a253e4ce556a5b75fa8b1.zip lz4-e2c9b19122a19fa8a46a253e4ce556a5b75fa8b1.tar.gz lz4-e2c9b19122a19fa8a46a253e4ce556a5b75fa8b1.tar.bz2 |
lz4frame : Added negative compression levels
Diffstat (limited to 'lib')
-rw-r--r-- | lib/lz4.h | 14 | ||||
-rw-r--r-- | lib/lz4frame.c | 12 | ||||
-rw-r--r-- | lib/lz4frame.h | 2 |
3 files changed, 14 insertions, 14 deletions
@@ -256,19 +256,19 @@ LZ4LIB_API int LZ4_loadDict (LZ4_stream_t* streamPtr, const char* dictionary, in /*! LZ4_compress_fast_continue() : * Compress buffer content 'src', using data from previously compressed blocks as dictionary to improve compression ratio. - * Important : Previous data blocks are assumed to still be present and unmodified ! + * Important : Previous data blocks are assumed to remain present and unmodified ! * 'dst' buffer must be already allocated. - * If maxDstSize >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster. + * If dstCapacity >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster. * If not, and if compressed data cannot fit into 'dst' buffer size, compression stops, and function returns a zero. + * After an error, the stream status is invalid, and it can only be reset or freed. */ -LZ4LIB_API int LZ4_compress_fast_continue (LZ4_stream_t* streamPtr, const char* src, char* dst, int srcSize, int maxDstSize, int acceleration); +LZ4LIB_API int LZ4_compress_fast_continue (LZ4_stream_t* streamPtr, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration); /*! LZ4_saveDict() : - * If previously compressed data block is not guaranteed to remain available at its memory location, + * If previously compressed data block is not guaranteed to remain available at its current memory location, * save it into a safer place (char* safeBuffer). - * Note : you don't need to call LZ4_loadDict() afterwards, - * dictionary is immediately usable, you can therefore call LZ4_compress_fast_continue(). - * Return : saved dictionary size in bytes (necessarily <= dictSize), or 0 if error. + * Note : it's not necessary to call LZ4_loadDict() after LZ4_saveDict(), dictionary is immediately usable. + * @return : saved dictionary size in bytes (necessarily <= dictSize), or 0 if error. */ LZ4LIB_API int LZ4_saveDict (LZ4_stream_t* streamPtr, char* safeBuffer, int dictSize); diff --git a/lib/lz4frame.c b/lib/lz4frame.c index fc0c7b5..356be8a 100644 --- a/lib/lz4frame.c +++ b/lib/lz4frame.c @@ -517,14 +517,14 @@ static size_t LZ4F_compressBlock(void* dst, const void* src, size_t srcSize, com static int LZ4F_localLZ4_compress_limitedOutput_withState(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level) { - (void) level; - return LZ4_compress_fast_extState(ctx, src, dst, srcSize, dstCapacity, 1); + int const acceleration = (level < -1) ? -level : 1; + return LZ4_compress_fast_extState(ctx, src, dst, srcSize, dstCapacity, acceleration); } static int LZ4F_localLZ4_compress_limitedOutput_continue(void* ctx, const char* src, char* dst, int srcSize, int dstCapacity, int level) { - (void) level; - return LZ4_compress_fast_continue((LZ4_stream_t*)ctx, src, dst, srcSize, dstCapacity, 1); + int const acceleration = (level < -1) ? -level : 1; + return LZ4_compress_fast_continue((LZ4_stream_t*)ctx, src, dst, srcSize, dstCapacity, acceleration); } static int LZ4F_localLZ4_compressHC_limitedOutput_continue(void* ctx, const char* src, char* dst, int srcSize, int dstSize, int level) @@ -619,7 +619,7 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci if (compressOptionsPtr->stableSrc) { cctxPtr->tmpIn = cctxPtr->tmpBuff; } else { - int realDictSize = LZ4F_localSaveDict(cctxPtr); + int const realDictSize = LZ4F_localSaveDict(cctxPtr); if (realDictSize==0) return err0r(LZ4F_ERROR_GENERIC); cctxPtr->tmpIn = cctxPtr->tmpBuff + realDictSize; } @@ -629,7 +629,7 @@ size_t LZ4F_compressUpdate(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapaci if ((cctxPtr->tmpIn + blockSize) > (cctxPtr->tmpBuff + cctxPtr->maxBufferSize) /* necessarily LZ4F_blockLinked && lastBlockCompressed==fromTmpBuffer */ && !(cctxPtr->prefs.autoFlush)) { - int realDictSize = LZ4F_localSaveDict(cctxPtr); + int const realDictSize = LZ4F_localSaveDict(cctxPtr); cctxPtr->tmpIn = cctxPtr->tmpBuff + realDictSize; } diff --git a/lib/lz4frame.h b/lib/lz4frame.h index 76b4e69..1b3e498 100644 --- a/lib/lz4frame.h +++ b/lib/lz4frame.h @@ -167,7 +167,7 @@ typedef struct { * All reserved fields must be set to zero. */ typedef struct { LZ4F_frameInfo_t frameInfo; - int compressionLevel; /* 0 == default (fast mode); values above LZ4HC_CLEVEL_MAX count as LZ4HC_CLEVEL_MAX; values below 0 count as 0 */ + int compressionLevel; /* 0 == default (fast mode); values above LZ4HC_CLEVEL_MAX count as LZ4HC_CLEVEL_MAX; values below 0 trigger "fast acceleration", proportional to value */ unsigned autoFlush; /* 1 == always flush (reduce usage of tmp buffer) */ unsigned reserved[4]; /* must be zero for forward compatibility */ } LZ4F_preferences_t; |