block-level API

lib/zstd_static.h

@@ -144,7 +144,7 @@ ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t maxDstSiz
   Note that dictionary presence is a "hidden" information,
   the decoder needs to be aware that it is required for proper decoding, or decoding will fail.
 
-  If you want to compress multiple messages using same dictionary,
+  If you want to compress a lot of messages using same dictionary,
   it can be beneficial to duplicate compression context rather than reloading dictionary each time.
   In such case, use ZSTD_duplicateCCtx(), which will need an already created ZSTD_CCtx,
   in order to duplicate compression context into it.
@@ -157,7 +157,7 @@ ZSTDLIB_API size_t ZSTD_compressEnd(ZSTD_CCtx* cctx, void* dst, size_t maxDstSiz
   Finish a frame with ZSTD_compressEnd(), which will write the epilogue.
   Without it, the frame will be considered incomplete by decoders.
 
-  You can then reuse ZSTD_CCtx to compress new frames.
+  You can then reuse ZSTD_CCtx to compress some new frame.
 */
 
 
@@ -196,9 +196,36 @@ ZSTDLIB_API size_t ZSTD_decompressContinue(ZSTD_DCtx* dctx, void* dst, size_t ma
   It can be zero, which is not an error; it just means ZSTD_decompressContinue() has decoded some header.
 
   A frame is fully decoded when ZSTD_nextSrcSizeToDecompress() returns zero.
+  Context can then be reset to start a new decompression.
 */
 
 
+/* **************************************
+*  Block functions
+****************************************/
+
+/*!Block functions produce and decode raw zstd blocks, without frame metadata.
+   It saves associated header sizes.
+   But user will have to save and regenerate fields required to regenerate data, such as block sizes.
+
+   A few rules to respect :
+   - Uncompressed block size must be <= 128 KB
+   - Compressing or decompressing require a context structure
+     + Use ZSTD_createXCtx() to create them
+   - It is necessary to init context before starting
+     + compression : ZSTD_compressBegin(), which allows selection of compression level or parameters
+     + decompression : ZSTD_resetDCtx()
+     + If you compress multiple blocks without resetting, next blocks will create references to previous ones
+   - Dictionary can optionally be inserted, using ZSTD_de/compress_insertDictionary()
+   - When a block is considered not compressible enough, ZSTD_compressBlock() result will be zero.
+     + User must test for such outcome and be able to deal with uncompressed data
+     + ZSTD_decompressBlock() doesn't accept uncompressed data as input
+*/
+
+size_t ZSTD_compressBlock  (ZSTD_CCtx* cctx, void* dst, size_t maxDstSize, const void* src, size_t srcSize);
+size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, const void* src, size_t srcSize);
+
+
 /* *************************************
 *  Pre-defined compression levels
 ***************************************/