diff options
Diffstat (limited to 'lib/lz4frame.c')
-rw-r--r-- | lib/lz4frame.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/lib/lz4frame.c b/lib/lz4frame.c index 3c2b788..626ac98 100644 --- a/lib/lz4frame.c +++ b/lib/lz4frame.c @@ -158,7 +158,7 @@ static void LZ4F_writeLE64 (void* dst, U64 value64) #define LZ4F_BLOCKSIZEID_DEFAULT LZ4F_max64KB static const size_t minFHSize = 7; -static const size_t maxFHSize = 15; /* max Frame Header Size */ +static const size_t maxFHSize = LZ4F_HEADER_SIZE_MAX; /* 15 */ static const size_t BHSize = 4; @@ -254,20 +254,27 @@ static LZ4F_blockSizeID_t LZ4F_optimalBSID(const LZ4F_blockSizeID_t requestedBSI return requestedBSID; } +/* LZ4F_compressBound() : + * Provides dstCapacity given a srcSize to guarantee operation success in worst case situations. + * prefsPtr is optional : you can provide NULL as argument, preferences will be set to cover worst case scenario. + * Result is always the same for a srcSize and prefsPtr, so it can be trusted to size reusable buffers. + * When srcSize==0, LZ4F_compressBound() provides an upper bound for LZ4F_flush() and LZ4F_compressEnd() operations. + */ static size_t LZ4F_compressBound_internal(size_t srcSize, const LZ4F_preferences_t* preferencesPtr, size_t alreadyBuffered) { LZ4F_preferences_t prefsNull; memset(&prefsNull, 0, sizeof(prefsNull)); prefsNull.frameInfo.contentChecksumFlag = LZ4F_contentChecksumEnabled; /* worst case */ { const LZ4F_preferences_t* const prefsPtr = (preferencesPtr==NULL) ? &prefsNull : preferencesPtr; + U32 const flush = prefsPtr->autoFlush | (srcSize==0); LZ4F_blockSizeID_t const bid = prefsPtr->frameInfo.blockSizeID; size_t const blockSize = LZ4F_getBlockSize(bid); size_t const maxBuffered = blockSize - 1; size_t const bufferedSize = MIN(alreadyBuffered, maxBuffered); size_t const maxSrcSize = srcSize + bufferedSize; unsigned const nbFullBlocks = (unsigned)(maxSrcSize / blockSize); - size_t const partialBlockSize = srcSize & (blockSize-1); - size_t const lastBlockSize = prefsPtr->autoFlush ? partialBlockSize : 0; + size_t const partialBlockSize = (srcSize - (srcSize==0)) & (blockSize-1); /* 0 => -1 == MAX => blockSize-1 */ + size_t const lastBlockSize = flush ? partialBlockSize : 0; unsigned const nbBlocks = nbFullBlocks + (lastBlockSize>0); size_t const blockHeaderSize = 4; /* default, without block CRC option (which cannot be generated with current API) */ @@ -398,7 +405,7 @@ LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_compressionContext_t LZ4F_comp /*! LZ4F_compressBegin() : * will write the frame header into dstBuffer. - * dstBuffer must be large enough to accommodate a header (dstCapacity). Maximum header size is LZ4F_MAXHEADERFRAME_SIZE bytes. + * dstBuffer must be large enough to accommodate a header (dstCapacity). Maximum header size is LZ4F_HEADER_SIZE_MAX bytes. * @return : number of bytes written into dstBuffer for the header * or an error code (can be tested using LZ4F_isError()) */ |