1 files changed, 97 insertions, 0 deletions
diff --git a/src/zstd/examples/dictionary_compression.c b/src/zstd/examples/dictionary_compression.c
new file mode 100644
index 000000000..d9aad45a7
--- /dev/null
+++ b/src/zstd/examples/dictionary_compression.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2016-2020 Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+#include <stdio.h>     // printf
+#include <stdlib.h>    // free
+#include <string.h>    // memset, strcat
+#include <zstd.h>      // presumes zstd library is installed
+#include "common.h"    // Helper functions, CHECK(), and CHECK_ZSTD()
+
+/* createDict() :
+   `dictFileName` is supposed to have been created using `zstd --train` */
+static ZSTD_CDict* createCDict_orDie(const char* dictFileName, int cLevel)
+{
+    size_t dictSize;
+    printf("loading dictionary %s \n", dictFileName);
+    void* const dictBuffer = mallocAndLoadFile_orDie(dictFileName, &dictSize);
+    ZSTD_CDict* const cdict = ZSTD_createCDict(dictBuffer, dictSize, cLevel);
+    CHECK(cdict != NULL, "ZSTD_createCDict() failed!");
+    free(dictBuffer);
+    return cdict;
+}
+
+
+static void compress(const char* fname, const char* oname, const ZSTD_CDict* cdict)
+{
+    size_t fSize;
+    void* const fBuff = mallocAndLoadFile_orDie(fname, &fSize);
+    size_t const cBuffSize = ZSTD_compressBound(fSize);
+    void* const cBuff = malloc_orDie(cBuffSize);
+
+    /* Compress using the dictionary.
+     * This function writes the dictionary id, and content size into the header.
+     * But, it doesn't use a checksum. You can control these options using the
+     * advanced API: ZSTD_CCtx_setParameter(), ZSTD_CCtx_refCDict(),
+     * and ZSTD_compress2().
+     */
+    ZSTD_CCtx* const cctx = ZSTD_createCCtx();
+    CHECK(cctx != NULL, "ZSTD_createCCtx() failed!");
+    size_t const cSize = ZSTD_compress_usingCDict(cctx, cBuff, cBuffSize, fBuff, fSize, cdict);
+    CHECK_ZSTD(cSize);
+
+    saveFile_orDie(oname, cBuff, cSize);
+
+    /* success */
+    printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
+
+    ZSTD_freeCCtx(cctx);   /* never fails */
+    free(fBuff);
+    free(cBuff);
+}
+
+
+static char* createOutFilename_orDie(const char* filename)
+{
+    size_t const inL = strlen(filename);
+    size_t const outL = inL + 5;
+    void* outSpace = malloc_orDie(outL);
+    memset(outSpace, 0, outL);
+    strcat(outSpace, filename);
+    strcat(outSpace, ".zst");
+    return (char*)outSpace;
+}
+
+int main(int argc, const char** argv)
+{
+    const char* const exeName = argv[0];
+    int const cLevel = 3;
+
+    if (argc<3) {
+        fprintf(stderr, "wrong arguments\n");
+        fprintf(stderr, "usage:\n");
+        fprintf(stderr, "%s [FILES] dictionary\n", exeName);
+        return 1;
+    }
+
+    /* load dictionary only once */
+    const char* const dictName = argv[argc-1];
+    ZSTD_CDict* const dictPtr = createCDict_orDie(dictName, cLevel);
+
+    int u;
+    for (u=1; u<argc-1; u++) {
+        const char* inFilename = argv[u];
+        char* const outFilename = createOutFilename_orDie(inFilename);
+        compress(inFilename, outFilename, dictPtr);
+        free(outFilename);
+    }
+
+    ZSTD_freeCDict(dictPtr);
+    printf("All %u files compressed. \n", argc-2);
+    return 0;
+}