1 files changed, 157 insertions, 0 deletions
diff --git a/src/zstd/examples/dictionary_compression.c b/src/zstd/examples/dictionary_compression.c
new file mode 100644
index 00000000..97bf8cb5
--- /dev/null
+++ b/src/zstd/examples/dictionary_compression.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2016-present, 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 <stdlib.h>    // malloc, exit
+#include <stdio.h>     // printf
+#include <string.h>    // strerror
+#include <errno.h>     // errno
+#include <sys/stat.h>  // stat
+#include <zstd.h>      // presumes zstd library is installed
+
+
+static off_t fsize_orDie(const char *filename)
+{
+    struct stat st;
+    if (stat(filename, &st) == 0) return st.st_size;
+    /* error */
+    perror(filename);
+    exit(1);
+}
+
+static FILE* fopen_orDie(const char *filename, const char *instruction)
+{
+    FILE* const inFile = fopen(filename, instruction);
+    if (inFile) return inFile;
+    /* error */
+    perror(filename);
+    exit(2);
+}
+
+static void* malloc_orDie(size_t size)
+{
+    void* const buff = malloc(size);
+    if (buff) return buff;
+    /* error */
+    perror("malloc");
+    exit(3);
+}
+
+static void* loadFile_orDie(const char* fileName, size_t* size)
+{
+    off_t const buffSize = fsize_orDie(fileName);
+    FILE* const inFile = fopen_orDie(fileName, "rb");
+    void* const buffer = malloc_orDie(buffSize);
+    size_t const readSize = fread(buffer, 1, buffSize, inFile);
+    if (readSize != (size_t)buffSize) {
+        fprintf(stderr, "fread: %s : %s \n", fileName, strerror(errno));
+        exit(4);
+    }
+    fclose(inFile);
+    *size = buffSize;
+    return buffer;
+}
+
+static void saveFile_orDie(const char* fileName, const void* buff, size_t buffSize)
+{
+    FILE* const oFile = fopen_orDie(fileName, "wb");
+    size_t const wSize = fwrite(buff, 1, buffSize, oFile);
+    if (wSize != (size_t)buffSize) {
+        fprintf(stderr, "fwrite: %s : %s \n", fileName, strerror(errno));
+        exit(5);
+    }
+    if (fclose(oFile)) {
+        perror(fileName);
+        exit(6);
+    }
+}
+
+/* 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 = loadFile_orDie(dictFileName, &dictSize);
+    ZSTD_CDict* const cdict = ZSTD_createCDict(dictBuffer, dictSize, cLevel);
+    if (!cdict) {
+        fprintf(stderr, "ZSTD_createCDict error \n");
+        exit(7);
+    }
+    free(dictBuffer);
+    return cdict;
+}
+
+
+static void compress(const char* fname, const char* oname, const ZSTD_CDict* cdict)
+{
+    size_t fSize;
+    void* const fBuff = loadFile_orDie(fname, &fSize);
+    size_t const cBuffSize = ZSTD_compressBound(fSize);
+    void* const cBuff = malloc_orDie(cBuffSize);
+
+    ZSTD_CCtx* const cctx = ZSTD_createCCtx();
+    if (cctx==NULL) { fprintf(stderr, "ZSTD_createCCtx() error \n"); exit(10); }
+    size_t const cSize = ZSTD_compress_usingCDict(cctx, cBuff, cBuffSize, fBuff, fSize, cdict);
+    if (ZSTD_isError(cSize)) {
+        fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
+        exit(7);
+    }
+
+    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;
+}