#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;
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) */
/*! 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())
*/
/* 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())
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())
*/
* 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.
FUZ_fillCompressibleNoiseBuffer(CNBuffer, COMPRESSIBLE_NOISE_LENGTH, compressibility, &randState);
crcOrig = XXH64(CNBuffer, COMPRESSIBLE_NOISE_LENGTH, 1);
+ /* LZ4F_compressBound() : special case : srcSize == 0 */
+ DISPLAYLEVEL(3, "LZ4F_compressBound(0) = ");
+ { size_t const cBound = LZ4F_compressBound(0, NULL);
+ if (cBound < 64 KB) goto _output_error;
+ DISPLAYLEVEL(3, " %u \n", (U32)cBound);
+ }
+
/* Special case : null-content frame */
testSize = 0;
DISPLAYLEVEL(3, "LZ4F_compressFrame, compress null content : \n");