lz4/examples/dictionaryRandomAccess.c
2021-09-07 01:02:23 +09:00

281 lines
8.0 KiB
C

// LZ4 API example : Dictionary Random Access
#if defined(_MSC_VER) && (_MSC_VER <= 1800) /* Visual Studio <= 2013 */
# define _CRT_SECURE_NO_WARNINGS
# define snprintf sprintf_s
#endif
#include "lz4.h"
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#define MIN(x, y) ((x) < (y) ? (x) : (y))
enum {
BLOCK_BYTES = 1024, /* 1 KiB of uncompressed data in a block */
DICTIONARY_BYTES = 1024, /* Load a 1 KiB dictionary */
MAX_BLOCKS = 1024 /* For simplicity of implementation */
};
/**
* Magic bytes for this test case.
* This is not a great magic number because it is a common word in ASCII.
* However, it is important to have some versioning system in your format.
*/
const char kTestMagic[] = { 'T', 'E', 'S', 'T' };
void write_int(FILE* fp, int i) {
size_t written = fwrite(&i, sizeof(i), 1, fp);
if (written != 1) { exit(10); }
}
void write_bin(FILE* fp, const void* array, size_t arrayBytes) {
size_t written = fwrite(array, 1, arrayBytes, fp);
if (written != arrayBytes) { exit(11); }
}
void read_int(FILE* fp, int* i) {
size_t read = fread(i, sizeof(*i), 1, fp);
if (read != 1) { exit(12); }
}
size_t read_bin(FILE* fp, void* array, size_t arrayBytes) {
size_t read = fread(array, 1, arrayBytes, fp);
if (ferror(fp)) { exit(12); }
return read;
}
void seek_bin(FILE* fp, long offset, int origin) {
if (fseek(fp, offset, origin)) { exit(14); }
}
void test_compress(FILE* outFp, FILE* inpFp, void *dict, int dictSize)
{
LZ4_stream_t lz4Stream_body;
LZ4_stream_t* lz4Stream = &lz4Stream_body;
char inpBuf[BLOCK_BYTES];
int offsets[MAX_BLOCKS];
int *offsetsEnd = offsets;
LZ4_initStream(lz4Stream, sizeof(*lz4Stream));
/* Write header magic */
write_bin(outFp, kTestMagic, sizeof(kTestMagic));
*offsetsEnd++ = sizeof(kTestMagic);
/* Write compressed data blocks. Each block contains BLOCK_BYTES of plain
data except possibly the last. */
for(;;) {
const int inpBytes = (int) read_bin(inpFp, inpBuf, BLOCK_BYTES);
if(0 == inpBytes) {
break;
}
/* Forget previously compressed data and load the dictionary */
LZ4_loadDict(lz4Stream, (const char*) dict, dictSize);
{
char cmpBuf[LZ4_COMPRESSBOUND(BLOCK_BYTES)];
const int cmpBytes = LZ4_compress_fast_continue(
lz4Stream, inpBuf, cmpBuf, inpBytes, sizeof(cmpBuf), 1);
if(cmpBytes <= 0) { exit(1); }
write_bin(outFp, cmpBuf, (size_t)cmpBytes);
/* Keep track of the offsets */
*offsetsEnd = *(offsetsEnd - 1) + cmpBytes;
++offsetsEnd;
}
if (offsetsEnd - offsets > MAX_BLOCKS) { exit(2); }
}
/* Write the tailing jump table */
{
int *ptr = offsets;
while (ptr != offsetsEnd) {
write_int(outFp, *ptr++);
}
write_int(outFp, (int) (offsetsEnd - offsets));
}
}
void test_decompress(FILE* outFp, FILE* inpFp, void *dict, int dictSize, int offset, int length)
{
LZ4_streamDecode_t lz4StreamDecode_body;
LZ4_streamDecode_t* lz4StreamDecode = &lz4StreamDecode_body;
/* The blocks [currentBlock, endBlock) contain the data we want */
int currentBlock = offset / BLOCK_BYTES;
int endBlock = ((offset + length - 1) / BLOCK_BYTES) + 1;
char decBuf[BLOCK_BYTES];
int offsets[MAX_BLOCKS];
/* Special cases */
if (length == 0) { return; }
/* Read the magic bytes */
{
char magic[sizeof(kTestMagic)];
size_t read = read_bin(inpFp, magic, sizeof(magic));
if (read != sizeof(magic)) { exit(1); }
if (memcmp(kTestMagic, magic, sizeof(magic))) { exit(2); }
}
/* Read the offsets tail */
{
int numOffsets;
int block;
int *offsetsPtr = offsets;
seek_bin(inpFp, -4, SEEK_END);
read_int(inpFp, &numOffsets);
if (numOffsets <= endBlock) { exit(3); }
seek_bin(inpFp, -4 * (numOffsets + 1), SEEK_END);
for (block = 0; block <= endBlock; ++block) {
read_int(inpFp, offsetsPtr++);
}
}
/* Seek to the first block to read */
seek_bin(inpFp, offsets[currentBlock], SEEK_SET);
offset = offset % BLOCK_BYTES;
/* Start decoding */
for(; currentBlock < endBlock; ++currentBlock) {
char cmpBuf[LZ4_COMPRESSBOUND(BLOCK_BYTES)];
/* The difference in offsets is the size of the block */
int cmpBytes = offsets[currentBlock + 1] - offsets[currentBlock];
{
const size_t read = read_bin(inpFp, cmpBuf, (size_t)cmpBytes);
if(read != (size_t)cmpBytes) { exit(4); }
}
/* Load the dictionary */
LZ4_setStreamDecode(lz4StreamDecode, (const char*) dict, dictSize);
{
const int decBytes = LZ4_decompress_safe_continue(
lz4StreamDecode, cmpBuf, decBuf, cmpBytes, BLOCK_BYTES);
if(decBytes <= 0) { exit(5); }
{
/* Write out the part of the data we care about */
int blockLength = MIN(length, (decBytes - offset));
write_bin(outFp, decBuf + offset, (size_t)blockLength);
offset = 0;
length -= blockLength;
}
}
}
}
int compare(FILE* fp0, FILE* fp1, int length)
{
int result = 0;
while(0 == result) {
char b0[4096];
char b1[4096];
const size_t r0 = read_bin(fp0, b0, MIN(length, (int)sizeof(b0)));
const size_t r1 = read_bin(fp1, b1, MIN(length, (int)sizeof(b1)));
result = (int) r0 - (int) r1;
if(0 == r0 || 0 == r1) {
break;
}
if(0 == result) {
result = memcmp(b0, b1, r0);
}
length -= r0;
}
return result;
}
int main(int argc, char* argv[])
{
char inpFilename[256] = { 0 };
char lz4Filename[256] = { 0 };
char decFilename[256] = { 0 };
char dictFilename[256] = { 0 };
int offset;
int length;
char dict[DICTIONARY_BYTES];
int dictSize;
if(argc < 5) {
printf("Usage: %s input dictionary offset length", argv[0]);
return 0;
}
snprintf(inpFilename, 256, "%s", argv[1]);
snprintf(lz4Filename, 256, "%s.lz4s-%d", argv[1], BLOCK_BYTES);
snprintf(decFilename, 256, "%s.lz4s-%d.dec", argv[1], BLOCK_BYTES);
snprintf(dictFilename, 256, "%s", argv[2]);
offset = atoi(argv[3]);
length = atoi(argv[4]);
printf("inp = [%s]\n", inpFilename);
printf("lz4 = [%s]\n", lz4Filename);
printf("dec = [%s]\n", decFilename);
printf("dict = [%s]\n", dictFilename);
printf("offset = [%d]\n", offset);
printf("length = [%d]\n", length);
/* Load dictionary */
{
FILE* dictFp = fopen(dictFilename, "rb");
dictSize = (int)read_bin(dictFp, dict, DICTIONARY_BYTES);
fclose(dictFp);
}
/* compress */
{
FILE* inpFp = fopen(inpFilename, "rb");
FILE* outFp = fopen(lz4Filename, "wb");
printf("compress : %s -> %s\n", inpFilename, lz4Filename);
test_compress(outFp, inpFp, dict, dictSize);
printf("compress : done\n");
fclose(outFp);
fclose(inpFp);
}
/* decompress */
{
FILE* inpFp = fopen(lz4Filename, "rb");
FILE* outFp = fopen(decFilename, "wb");
printf("decompress : %s -> %s\n", lz4Filename, decFilename);
test_decompress(outFp, inpFp, dict, DICTIONARY_BYTES, offset, length);
printf("decompress : done\n");
fclose(outFp);
fclose(inpFp);
}
/* verify */
{
FILE* inpFp = fopen(inpFilename, "rb");
FILE* decFp = fopen(decFilename, "rb");
seek_bin(inpFp, offset, SEEK_SET);
printf("verify : %s <-> %s\n", inpFilename, decFilename);
const int cmp = compare(inpFp, decFp, length);
if(0 == cmp) {
printf("verify : OK\n");
} else {
printf("verify : NG\n");
}
fclose(decFp);
fclose(inpFp);
}
return 0;
}