zstd/examples/dictionary_compression.c
2019-04-05 21:02:07 -07:00

98 lines
3.2 KiB
C

/*
* 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 <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;
}