added : ZSTD_createCDict_byReference()

Makefile

@@ -30,6 +30,8 @@ all:
 	$(MAKE) -C $(ZSTDDIR) $@
 	$(MAKE) -C $(PRGDIR) $@ zstd32
 	$(MAKE) -C $(TESTDIR) $@ all32
+	$(MAKE) -C $(ZWRAPDIR) $@
+	CPPFLAGS=-I../lib LDFLAGS=-L../lib $(MAKE) -C examples/ $@
 
 .PHONY: lib
 lib:
@@ -54,6 +56,7 @@ clean:
 	@$(MAKE) -C $(PRGDIR) $@ > $(VOID)
 	@$(MAKE) -C $(TESTDIR) $@ > $(VOID)
 	@$(MAKE) -C $(ZWRAPDIR) $@ > $(VOID)
+	@$(MAKE) -C examples/ $@ > $(VOID)
 	@$(RM) zstd$(EXT) tmp*
 	@echo Cleaning completed
 

lib/compress/zstd_compress.c

@@ -2733,8 +2733,10 @@ size_t ZSTD_compress(void* dst, size_t dstCapacity, const void* src, size_t srcS
 /* =====  Dictionary API  ===== */
 
 struct ZSTD_CDict_s {
-    void* dictContent;
+    void* dictBuffer;
+    const void* dictContent;
     size_t dictContentSize;
+    unsigned byReference;
     ZSTD_CCtx* refContext;
 };  /* typedef'd tp ZSTD_CDict within "zstd.h" */
 
@@ -2744,36 +2746,44 @@ size_t ZSTD_sizeof_CDict(const ZSTD_CDict* cdict)
     return ZSTD_sizeof_CCtx(cdict->refContext) + cdict->dictContentSize;
 }
 
-ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, ZSTD_parameters params, ZSTD_customMem customMem)
+ZSTD_CDict* ZSTD_createCDict_advanced(const void* dictBuffer, size_t dictSize, unsigned byReference,
+                                      ZSTD_parameters params, ZSTD_customMem customMem)
 {
     if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem;
     if (!customMem.customAlloc || !customMem.customFree) return NULL;
 
     {   ZSTD_CDict* const cdict = (ZSTD_CDict*) ZSTD_malloc(sizeof(ZSTD_CDict), customMem);
-        void* const dictContent = ZSTD_malloc(dictSize, customMem);
         ZSTD_CCtx* const cctx = ZSTD_createCCtx_advanced(customMem);
 
-        if (!dictContent || !cdict || !cctx) {
+        if (!cdict || !cctx) {
-            ZSTD_free(dictContent, customMem);
             ZSTD_free(cdict, customMem);
             ZSTD_free(cctx, customMem);
             return NULL;
         }
 
-        if (dictSize) {
+        if ((byReference) || (!dictBuffer) || (!dictSize)) {
-            memcpy(dictContent, dict, dictSize);
+            cdict->dictBuffer = NULL;
+            cdict->dictContent = dictBuffer;
+            cdict->byReference = 1;
+        } else {
+            void* const internalBuffer = ZSTD_malloc(dictSize, customMem);
+            if (!internalBuffer) return NULL;
+            memcpy(internalBuffer, dictBuffer, dictSize);
+            cdict->dictBuffer = internalBuffer;
+            cdict->dictContent = internalBuffer;
+            cdict->byReference = 0;
         }
-        {   size_t const errorCode = ZSTD_compressBegin_advanced(cctx, dictContent, dictSize, params, 0);
+
+        {   size_t const errorCode = ZSTD_compressBegin_advanced(cctx, cdict->dictContent, dictSize, params, 0);
             if (ZSTD_isError(errorCode)) {
-                ZSTD_free(dictContent, customMem);
+                ZSTD_free(cdict->dictBuffer, customMem);
-                ZSTD_free(cdict, customMem);
                 ZSTD_free(cctx, customMem);
+                ZSTD_free(cdict, customMem);
                 return NULL;
         }   }
 
-        cdict->dictContent = dictContent;
-        cdict->dictContentSize = dictSize;
         cdict->refContext = cctx;
+        cdict->dictContentSize = dictSize;
         return cdict;
     }
 }
@@ -2783,7 +2793,15 @@ ZSTD_CDict* ZSTD_createCDict(const void* dict, size_t dictSize, int compressionL
     ZSTD_customMem const allocator = { NULL, NULL, NULL };
     ZSTD_parameters params = ZSTD_getParams(compressionLevel, 0, dictSize);
     params.fParams.contentSizeFlag = 1;
-    return ZSTD_createCDict_advanced(dict, dictSize, params, allocator);
+    return ZSTD_createCDict_advanced(dict, dictSize, 0, params, allocator);
+}
+
+ZSTD_CDict* ZSTD_createCDict_byReference(const void* dict, size_t dictSize, int compressionLevel)
+{
+    ZSTD_customMem const allocator = { NULL, NULL, NULL };
+    ZSTD_parameters params = ZSTD_getParams(compressionLevel, 0, dictSize);
+    params.fParams.contentSizeFlag = 1;
+    return ZSTD_createCDict_advanced(dict, dictSize, 1, params, allocator);
 }
 
 size_t ZSTD_freeCDict(ZSTD_CDict* cdict)
@@ -2791,7 +2809,7 @@ size_t ZSTD_freeCDict(ZSTD_CDict* cdict)
     if (cdict==NULL) return 0;   /* support free on NULL */
     {   ZSTD_customMem const cMem = cdict->refContext->customMem;
         ZSTD_freeCCtx(cdict->refContext);
-        ZSTD_free(cdict->dictContent, cMem);
+        if (!cdict->byReference) ZSTD_free(cdict->dictBuffer, cMem);
         ZSTD_free(cdict, cMem);
         return 0;
     }
@@ -2939,7 +2957,7 @@ size_t ZSTD_initCStream_advanced(ZSTD_CStream* zcs,
 
     if (dict) {
         ZSTD_freeCDict(zcs->cdictLocal);
-        zcs->cdictLocal = ZSTD_createCDict_advanced(dict, dictSize, params, zcs->customMem);
+        zcs->cdictLocal = ZSTD_createCDict_advanced(dict, dictSize, 0, params, zcs->customMem);
         if (zcs->cdictLocal == NULL) return ERROR(memory_allocation);
         zcs->cdict = zcs->cdictLocal;
     } else zcs->cdict = NULL;

lib/zstd.h

@@ -173,8 +173,8 @@ typedef struct ZSTD_CDict_s ZSTD_CDict;
 *   When compressing multiple messages / blocks with the same dictionary, it's recommended to load it just once.
 *   ZSTD_createCDict() will create a digested dictionary, ready to start future compression operations without startup delay.
 *   ZSTD_CDict can be created once and used by multiple threads concurrently, as its usage is read-only.
-*   `dict` can be released after ZSTD_CDict creation. */
+*   `dictBuffer` can be released after ZSTD_CDict creation, as its content is copied within CDict */
-ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dict, size_t dictSize, int compressionLevel);
+ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict(const void* dictBuffer, size_t dictSize, int compressionLevel);
 
 /*! ZSTD_freeCDict() :
 *   Function frees memory allocated by ZSTD_createCDict(). */
@@ -400,9 +400,15 @@ ZSTDLIB_API ZSTD_CCtx* ZSTD_createCCtx_advanced(ZSTD_customMem customMem);
  *  Gives the amount of memory used by a given ZSTD_CCtx */
 ZSTDLIB_API size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);
 
+/*! ZSTD_createCDict_byReference() :
+ *  Create a digested dictionary for compression
+ *  Dictionary content is simply referenced, and therefore stays in dictBuffer.
+ *  It is important that dictBuffer outlives CDict, it must remain read accessible throughout the lifetime of CDict */
+ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel);
+
 /*! ZSTD_createCDict_advanced() :
  *  Create a ZSTD_CDict using external alloc and free, and customized compression parameters */
-ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize,
+ZSTDLIB_API ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, unsigned byReference,
                                                   ZSTD_parameters params, ZSTD_customMem customMem);
 
 /*! ZSTD_sizeof_CDict() :

programs/bench.c

@@ -236,7 +236,7 @@ static int BMK_benchMem(const void* srcBuffer, size_t srcSize,
                     ZSTD_customMem const cmem = { NULL, NULL, NULL };
                     U64 clockLoop = g_nbSeconds ? TIMELOOP_MICROSEC : 1;
                     U32 nbLoops = 0;
-                    ZSTD_CDict* const cdict = ZSTD_createCDict_advanced(dictBuffer, dictBufferSize, zparams, cmem);
+                    ZSTD_CDict* const cdict = ZSTD_createCDict_advanced(dictBuffer, dictBufferSize, 1, zparams, cmem);
                     if (cdict==NULL) EXM_THROW(1, "ZSTD_createCDict_advanced() allocation failure");
                     if (comprParams->windowLog) zparams.cParams.windowLog = comprParams->windowLog;
                     if (comprParams->chainLog) zparams.cParams.chainLog = comprParams->chainLog;

zlibWrapper/examples/zwrapbench.c

@@ -234,7 +234,7 @@ static int BMK_benchMem(z_const void* srcBuffer, size_t srcSize,
                 if (compressor == BMK_ZSTD) {
                     ZSTD_parameters const zparams = ZSTD_getParams(cLevel, avgSize, dictBufferSize);
                     ZSTD_customMem const cmem = { NULL, NULL, NULL };
-                    ZSTD_CDict* cdict = ZSTD_createCDict_advanced(dictBuffer, dictBufferSize, zparams, cmem);
+                    ZSTD_CDict* cdict = ZSTD_createCDict_advanced(dictBuffer, dictBufferSize, 1, zparams, cmem);
                     if (cdict==NULL) EXM_THROW(1, "ZSTD_createCDict_advanced() allocation failure");
 
                     do {