diff options
Diffstat (limited to 'lib/lz4frame.h')
-rw-r--r-- | lib/lz4frame.h | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/lib/lz4frame.h b/lib/lz4frame.h index 3104d2e..a4a4ce6 100644 --- a/lib/lz4frame.h +++ b/lib/lz4frame.h @@ -206,10 +206,11 @@ LZ4FLIB_API LZ4F_errorCode_t LZ4F_freeCompressionContext(LZ4F_cctx* cctx); /* Compression */ +#define LZ4F_HEADER_SIZE_MAX 15 LZ4FLIB_API size_t LZ4F_compressBegin(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const LZ4F_preferences_t* prefsPtr); /* LZ4F_compressBegin() : * will write the frame header into dstBuffer. - * dstBuffer must be large enough to accommodate a header. Maximum header size is 15 bytes. + * dstCapacity must be large enough to store the header. Maximum header size is LZ4F_HEADER_SIZE_MAX bytes. * `prefsPtr` is optional : you can provide NULL as argument, all preferences will then be set to default. * @return : number of bytes written into dstBuffer for the header * or an error code (which can be tested using LZ4F_isError()) @@ -217,20 +218,20 @@ LZ4FLIB_API size_t LZ4F_compressBegin(LZ4F_cctx* cctx, void* dstBuffer, size_t d LZ4FLIB_API size_t LZ4F_compressBound(size_t srcSize, const LZ4F_preferences_t* prefsPtr); /* LZ4F_compressBound() : - * Provides the minimum size of Dst buffer given srcSize to handle worst case situations. - * Different preferences can produce different results. - * prefsPtr is optional : you can provide NULL as argument, all preferences will then be set to cover worst case. - * This function includes frame termination cost (4 bytes, or 8 if frame checksum is enabled) + * 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. */ LZ4FLIB_API size_t LZ4F_compressUpdate(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const void* srcBuffer, size_t srcSize, const LZ4F_compressOptions_t* cOptPtr); /* LZ4F_compressUpdate() : * LZ4F_compressUpdate() can be called repetitively to compress as much data as necessary. - * An important rule is that dstBuffer MUST be large enough (dstCapacity) to ensure compression completion even in worst case. - * This value is provided by using LZ4F_compressBound(). + * An important rule is that dstCapacity MUST be large enough to ensure operation success even in worst case situations. + * This value is provided by LZ4F_compressBound(). * If this condition is not respected, LZ4F_compress() will fail (result is an errorCode). * LZ4F_compressUpdate() doesn't guarantee error recovery. When an error occurs, compression context must be freed or resized. - * `cOptPtr` is optional : it's possible to provide NULL, all options will be set to default. + * `cOptPtr` is optional : NULL can be provided, in which case all options are set to default. * @return : number of bytes written into `dstBuffer` (it can be zero, meaning input data was just buffered). * or an error code if it fails (which can be tested using LZ4F_isError()) */ @@ -245,12 +246,12 @@ LZ4FLIB_API size_t LZ4F_flush(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapaci * or an error code if it fails (which can be tested using LZ4F_isError()) */ -LZ4FLIB_API size_t LZ4F_compressEnd(LZ4F_cctx* cctx, void* dstBuffer, size_t dstMaxSize, const LZ4F_compressOptions_t* cOptPtr); +LZ4FLIB_API size_t LZ4F_compressEnd(LZ4F_cctx* cctx, void* dstBuffer, size_t dstCapacity, const LZ4F_compressOptions_t* cOptPtr); /* LZ4F_compressEnd() : - * To properly finish the compressed frame, invoke LZ4F_compressEnd(). + * To properly finish an LZ4 frame, invoke LZ4F_compressEnd(). * It will flush whatever data remained within `cctx` (like LZ4_flush()) * and properly finalize the frame, with an endMark and a checksum. - * `cOptPtr` is optional : it's possible to provide NULL, all options will be set to default. + * `cOptPtr` is optional : NULL can be provided, in which case all options will be set to default. * @return : number of bytes written into dstBuffer (necessarily >= 4 (endMark), or 8 if optional frame checksum is enabled) * or an error code if it fails (which can be tested using LZ4F_isError()) * A successful call to LZ4F_compressEnd() makes `cctx` available again for another compression task. |