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