用c++实现 DEFLATE 算法的示例代码
时间: 2023-02-06 10:40:25 浏览: 136
DEFLATE 算法是一种常用的数据压缩算法,它通过使用 LZ77 算法和 Huffman 编码来实现压缩。下面是用 C 语言实现 DEFLATE 算法的一个简单示例:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define WINDOW_SIZE 4096
#define MIN_MATCH_LENGTH 3
int deflate(FILE *in, FILE *out) {
unsigned char window[WINDOW_SIZE];
unsigned char buffer[WINDOW_SIZE];
int window_pos = 0;
int buffer_pos = 0;
while (1) {
int best_match_length = 0;
int best_match_distance = 0;
// 查找最佳匹配
for (int i = 0; i < WINDOW_SIZE; i++) {
int match_length = 0;
while (match_length < WINDOW_SIZE &&
buffer[buffer_pos + match_length] == window[(window_pos - i + match_length) % WINDOW_SIZE]) {
match_length++;
}
if (match_length > best_match_length) {
best_match_length = match_length;
best_match_distance = i;
}
}
// 如果找到了最佳匹配,则将匹配长度和距离写入输出文件
if (best_match_length >= MIN_MATCH_LENGTH) {
fputc((best_match_length - MIN_MATCH_LENGTH) & 0xff, out);
fputc(((best_match_length - MIN_MATCH_LENGTH) >> 8) & 0xff, out);
fputc(best_match_distance & 0xff, out);
fputc((best_match_distance >> 8) & 0xff, out);
// 更新窗口位置和缓冲区位置
window_pos = (window_pos + best_match_length) % WINDOW_SIZE;
buffer_pos += best_match_length;
} else {
// 否则,将单个字节写入输出文件
fputc(buffer[buffer_pos], out);
// 更新窗口位置和缓冲区位置
window[window_pos] = buffer[buffer_pos];
window_pos = (window_pos + 1) % WINDOW_