added dictionary_compression.c example

examples/.gitignore

@@ -1,6 +1,7 @@
 #build
 simple_compression
 simple_decompression
+dictionary_compression
 dictionary_decompression
 
 #test artefact

examples/Makefile

@@ -30,7 +30,8 @@ LDFLAGS+= -lzstd
 
 default: all
 
-all: simple_compression simple_decompression dictionary_decompression
+all: simple_compression simple_decompression \
+	dictionary_compression dictionary_decompression
 
 simple_compression : simple_compression.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
@@ -38,12 +39,16 @@ simple_compression : simple_compression.c
 simple_decompression : simple_decompression.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
 
+dictionary_compression : dictionary_compression.c
+	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+
 dictionary_decompression : dictionary_decompression.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
 
 clean:
 	@rm -f core *.o tmp* result* *.zst \
-        simple_compression simple_decompression dictionary_decompression
+        simple_compression simple_decompression \
+		dictionary_compression dictionary_decompression
 	@echo Cleaning completed
 
 test: all

examples/dictionary_compression.c

@@ -0,0 +1,163 @@
+/*
+  Dictionary decompression
+  Educational program using zstd library
+  Copyright (C) Yann Collet 2016
+
+  GPL v2 License
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along
+  with this program; if not, write to the Free Software Foundation, Inc.,
+  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+  You can contact the author at :
+  - zstd homepage : http://www.zstd.net/
+*/
+
+#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_X(const char *filename)
+{
+    struct stat st;
+    if (stat(filename, &st) == 0) return st.st_size;
+    /* error */
+    perror(filename);
+    exit(1);
+}
+
+static FILE* fopen_X(const char *filename, const char *instruction)
+{
+    FILE* const inFile = fopen(filename, instruction);
+    if (inFile) return inFile;
+    /* error */
+    perror(filename);
+    exit(2);
+}
+
+static void* malloc_X(size_t size)
+{
+    void* const buff = malloc(size);
+    if (buff) return buff;
+    /* error */
+    perror(NULL);
+    exit(3);
+}
+
+static void* loadFile_X(const char* fileName, size_t* size)
+{
+    off_t const buffSize = fsize_X(fileName);
+    FILE* const inFile = fopen_X(fileName, "rb");
+    void* const buffer = malloc_X(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_X(const char* fileName, const void* buff, size_t buffSize)
+{
+    FILE* const oFile = fopen_X(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 const ZSTD_CDict* createDict(const char* dictFileName)
+{
+    size_t dictSize;
+    printf("loading dictionary %s \n", dictFileName);
+    void* const dictBuffer = loadFile_X(dictFileName, &dictSize);
+    const ZSTD_CDict* const ddict = ZSTD_createCDict(dictBuffer, dictSize, 3);
+    free(dictBuffer);
+    return ddict;
+}
+
+
+static void compress(const char* fname, const char* oname, const ZSTD_CDict* cdict)
+{
+    size_t fSize;
+    void* const fBuff = loadFile_X(fname, &fSize);
+    size_t const cBuffSize = ZSTD_compressBound(fSize);
+    void* const cBuff = malloc_X(cBuffSize);
+
+    ZSTD_CCtx* const cctx = ZSTD_createCCtx();
+    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_X(oname, cBuff, cSize);
+
+    /* success */
+    printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
+
+    ZSTD_freeCCtx(cctx);
+    free(fBuff);
+    free(cBuff);
+}
+
+
+static char* createOutFilename(const char* filename)
+{
+    size_t const inL = strlen(filename);
+    size_t const outL = inL + 5;
+    void* outSpace = malloc_X(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];
+
+    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];
+    const ZSTD_CDict* const dictPtr = createDict(dictName);
+
+    int u;
+    for (u=1; u<argc-1; u++) {
+        const char* inFilename = argv[u];
+        char* const outFilename = createOutFilename(inFilename);
+        compress(inFilename, outFilename, dictPtr);
+        free(outFilename);
+    }
+
+    printf("All %u files compressed. \n", argc-2);
+}

examples/dictionary_decompression.c

@@ -132,5 +132,5 @@ int main(int argc, const char** argv)
     int u;
     for (u=1; u<argc-1; u++) decompress(argv[u], dictPtr);
 
-    printf("All %u files decoded. \n", argc-2);
+    printf("All %u files correctly decoded (in memory) \n", argc-2);
 }