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author | Yann Collet <Cyan4973@users.noreply.github.com> | 2017-04-11 21:43:11 (GMT) |
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committer | GitHub <noreply@github.com> | 2017-04-11 21:43:11 (GMT) |
commit | 31e9ed612bfafade0a8589fb71b6f1f43bd439c2 (patch) | |
tree | c713ab373bca1e02a55036432a90fe8782e31197 /lib | |
parent | e2827775ee80d2ef985858727575df31fc60f1f3 (diff) | |
parent | e2c9b19122a19fa8a46a253e4ce556a5b75fa8b1 (diff) | |
download | lz4-31e9ed612bfafade0a8589fb71b6f1f43bd439c2.zip lz4-31e9ed612bfafade0a8589fb71b6f1f43bd439c2.tar.gz lz4-31e9ed612bfafade0a8589fb71b6f1f43bd439c2.tar.bz2 |
Merge pull request #347 from lz4/negativeCLevels
Negative Compression levels
Diffstat (limited to 'lib')
-rw-r--r-- | lib/lz4.h | 14 | ||||
-rw-r--r-- | lib/lz4frame.c | 28 | ||||
-rw-r--r-- | lib/lz4frame.h | 2 |
3 files changed, 23 insertions, 21 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 e04fe83..356be8a 100644 --- a/lib/lz4frame.c +++ b/lib/lz4frame.c @@ -316,11 +316,11 @@ size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBu BYTE* dstPtr = dstStart; BYTE* const dstEnd = dstStart + dstCapacity; - memset(&cctxI, 0, sizeof(cctxI)); /* works because no allocation */ + memset(&cctxI, 0, sizeof(cctxI)); memset(&options, 0, sizeof(options)); cctxI.version = LZ4F_VERSION; - cctxI.maxBufferSize = 5 MB; /* mess with real buffer size to prevent allocation; works because autoflush==1 & stableSrc==1 */ + cctxI.maxBufferSize = 5 MB; /* mess with real buffer size to prevent dynamic allocation; works because autoflush==1 & stableSrc==1 */ if (preferencesPtr!=NULL) prefs = *preferencesPtr; @@ -332,7 +332,7 @@ size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBu if (prefs.compressionLevel < LZ4HC_CLEVEL_MIN) { cctxI.lz4CtxPtr = &lz4ctx; cctxI.lz4CtxLevel = 1; - } + } /* otherwise : will be created within LZ4F_compressBegin */ prefs.frameInfo.blockSizeID = LZ4F_optimalBSID(prefs.frameInfo.blockSizeID, srcSize); prefs.autoFlush = 1; @@ -341,7 +341,7 @@ size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBu options.stableSrc = 1; - if (dstCapacity < LZ4F_compressFrameBound(srcSize, &prefs)) + if (dstCapacity < LZ4F_compressFrameBound(srcSize, &prefs)) /* condition to guarantee success */ return err0r(LZ4F_ERROR_dstMaxSize_tooSmall); { size_t const headerSize = LZ4F_compressBegin(&cctxI, dstBuffer, dstCapacity, &prefs); /* write header */ @@ -356,7 +356,7 @@ size_t LZ4F_compressFrame(void* dstBuffer, size_t dstCapacity, const void* srcBu if (LZ4F_isError(tailSize)) return tailSize; dstPtr += tailSize; } - if (prefs.compressionLevel >= LZ4HC_CLEVEL_MIN) /* no allocation done with lz4 fast */ + if (prefs.compressionLevel >= LZ4HC_CLEVEL_MIN) /* Ctx allocation only for lz4hc */ FREEMEM(cctxI.lz4CtxPtr); return (dstPtr - dstStart); @@ -423,7 +423,7 @@ size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacit if (preferencesPtr == NULL) preferencesPtr = &prefNull; cctxPtr->prefs = *preferencesPtr; - /* ctx Management */ + /* Ctx Management */ { U32 const tableID = (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) ? 1 : 2; /* 0:nothing ; 1:LZ4 table ; 2:HC tables */ if (cctxPtr->lz4CtxLevel < tableID) { FREEMEM(cctxPtr->lz4CtxPtr); @@ -431,6 +431,7 @@ size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacit cctxPtr->lz4CtxPtr = (void*)LZ4_createStream(); else cctxPtr->lz4CtxPtr = (void*)LZ4_createStreamHC(); + if (cctxPtr->lz4CtxPtr == NULL) return err0r(LZ4F_ERROR_allocation_failed); cctxPtr->lz4CtxLevel = tableID; } } @@ -444,10 +445,11 @@ size_t LZ4F_compressBegin(LZ4F_cctx* cctxPtr, void* dstBuffer, size_t dstCapacit requiredBuffSize = (cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) * 64 KB; /* just needs dict */ if (cctxPtr->maxBufferSize < requiredBuffSize) { - cctxPtr->maxBufferSize = requiredBuffSize; + cctxPtr->maxBufferSize = 0; FREEMEM(cctxPtr->tmpBuff); cctxPtr->tmpBuff = (BYTE*)ALLOCATOR(requiredBuffSize); if (cctxPtr->tmpBuff == NULL) return err0r(LZ4F_ERROR_allocation_failed); + cctxPtr->maxBufferSize = requiredBuffSize; } cctxPtr->tmpIn = cctxPtr->tmpBuff; cctxPtr->tmpInSize = 0; @@ -515,14 +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) @@ -617,7 +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; } @@ -627,7 +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; |