extended static dictionary to buffered mode

lib/zstd_buffered.c

@@ -160,6 +160,12 @@ size_t ZBUFF_compressInit(ZBUFF_CCtx* zbc, int compressionLevel)
 }
 
 
+ZSTDLIB_API size_t ZBUFF_compressWithDictionary(ZBUFF_CCtx* zbc, const void* src, size_t srcSize)
+{
+    ZSTD_compress_insertDictionary(zbc->zc, src, srcSize);
+    return 0;
+}
+
 
 /* *** Compression *** */
 
@@ -327,6 +333,8 @@ struct ZBUFF_DCtx_s {
     size_t outStart;
     size_t outEnd;
     size_t hPos;
+    const char* dict;
+    size_t dictSize;
     ZBUFF_dStage stage;
     unsigned char headerBuffer[ZSTD_frameHeaderSize_max];
 };   /* typedef'd to ZBUFF_DCtx within "zstd_buffered.h" */
@@ -353,17 +361,23 @@ size_t ZBUFF_freeDCtx(ZBUFF_DCtx* zbc)
 }
 
 
-
 /* *** Initialization *** */
 
 size_t ZBUFF_decompressInit(ZBUFF_DCtx* zbc)
 {
     zbc->stage = ZBUFFds_readHeader;
-    zbc->hPos = zbc->inPos = zbc->outStart = zbc->outEnd = 0;
+    zbc->hPos = zbc->inPos = zbc->outStart = zbc->outEnd = zbc->dictSize = 0;
     return ZSTD_resetDCtx(zbc->zc);
 }
 
 
+size_t ZBUFF_decompressWithDictionary(ZBUFF_DCtx* zbc, const void* src, size_t srcSize)
+{
+    zbc->dict = src;
+    zbc->dictSize = srcSize;
+    return 0;
+}
+
 
 /* *** Decompression *** */
 
@@ -442,6 +456,8 @@ size_t ZBUFF_decompressContinue(ZBUFF_DCtx* zbc, void* dst, size_t* maxDstSizePt
                         if (zbc->outBuff == NULL) return ERROR(memory_allocation);
                     }
                 }
+                if (zbc->dictSize)
+                    ZSTD_decompress_insertDictionary(zbc->zc, zbc->dict, zbc->dictSize);
                 if (zbc->hPos)
                 {
                     /* some data already loaded into headerBuffer : transfer into inBuff */

lib/zstd_buffered.h

@@ -69,6 +69,7 @@ ZSTDLIB_API ZBUFF_CCtx* ZBUFF_createCCtx(void);
 ZSTDLIB_API size_t      ZBUFF_freeCCtx(ZBUFF_CCtx* cctx);
 
 ZSTDLIB_API size_t ZBUFF_compressInit(ZBUFF_CCtx* cctx, int compressionLevel);
+ZSTDLIB_API size_t ZBUFF_compressWithDictionary(ZBUFF_CCtx* cctx, const void* src, size_t srcSize);
 ZSTDLIB_API size_t ZBUFF_compressContinue(ZBUFF_CCtx* cctx, void* dst, size_t* maxDstSizePtr, const void* src, size_t* srcSizePtr);
 ZSTDLIB_API size_t ZBUFF_compressFlush(ZBUFF_CCtx* cctx, void* dst, size_t* maxDstSizePtr);
 ZSTDLIB_API size_t ZBUFF_compressEnd(ZBUFF_CCtx* cctx, void* dst, size_t* maxDstSizePtr);
@@ -81,6 +82,9 @@ ZSTDLIB_API size_t ZBUFF_compressEnd(ZBUFF_CCtx* cctx, void* dst, size_t* maxDst
 *  Use ZBUFF_compressInit() to start a new compression operation.
 *  ZBUFF_CCtx objects can be reused multiple times.
 *
+*  Optionally, a reference to a static dictionary can be created with ZBUFF_compressWithDictionary()
+*  Note that the dictionary content must remain accessible during the compression process.
+*
 *  Use ZBUFF_compressContinue() repetitively to consume input stream.
 *  *srcSizePtr and *maxDstSizePtr can be any size.
 *  The function will report how many bytes were read or written within *srcSizePtr and *maxDstSizePtr.
@@ -115,6 +119,8 @@ ZSTDLIB_API ZBUFF_DCtx* ZBUFF_createDCtx(void);
 ZSTDLIB_API size_t      ZBUFF_freeDCtx(ZBUFF_DCtx* dctx);
 
 ZSTDLIB_API size_t ZBUFF_decompressInit(ZBUFF_DCtx* dctx);
+ZSTDLIB_API size_t ZBUFF_decompressWithDictionary(ZBUFF_DCtx* dctx, const void* src, size_t srcSize);
+
 ZSTDLIB_API size_t ZBUFF_decompressContinue(ZBUFF_DCtx* dctx, void* dst, size_t* maxDstSizePtr, const void* src, size_t* srcSizePtr);
 
 /** ************************************************
@@ -125,6 +131,10 @@ ZSTDLIB_API size_t ZBUFF_decompressContinue(ZBUFF_DCtx* dctx, void* dst, size_t*
 *  Use ZBUFF_decompressInit() to start a new decompression operation.
 *  ZBUFF_DCtx objects can be reused multiple times.
 *
+*  Optionally, a reference to a static dictionary can be set, using ZBUFF_decompressWithDictionary()
+*  It must be the same content as the one set during compression phase.
+*  Dictionary content must remain accessible during the decompression process.
+*
 *  Use ZBUFF_decompressContinue() repetitively to consume your input.
 *  *srcSizePtr and *maxDstSizePtr can be any size.
 *  The function will report how many bytes were read or written by modifying *srcSizePtr and *maxDstSizePtr.