[数据结构和算法]LZ77压缩算法三部曲——3.解压算法(C语言)

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压缩算法后面有需要再补写，先记录一下解压算法吧。
压缩算法用Java写的，压缩的是字节流。（测试原数据1024bytes–压缩后为201bytes）

直接上菜吧

#include <stdio.h>
#include <stdlib.h>
#include <string.h>#define BUFFER_LEN	128
#define SLIDE_LEN	512
#define MAX_STRING_LEN 2000typedef struct ENCODE{short off;unsigned char len;unsigned char ch;
}ENCODE_TypeDef;typedef struct unzip{int strLen;	//解压字符偏移值 unsigned char str[MAX_STRING_LEN];	//原字符串 unsigned char slide[SLIDE_LEN];	//滑动窗口大小unsigned char buf[BUFFER_LEN];	//前向缓冲区 
}unzip_TypeDef;const unsigned char table[] = {0x00,0x00,0x00,0x00,0x00,0x03,0x00,0x00,0x80,0x00,0x00,0x38,0x00,0x00,0x30,0x00,0x00,0xE0,0x00,0x00,0xC0,0xF9,0x03,0x00,0xFE,0x05,0x00,0xFB,0x0B,0x00,0xF5,0x17,0x00,0xE9,0x2F,0x00,0xFD,0x07,0x07,0xC8,0x03,0x70,0x00,0x00,0xE3,0xF7,0x0B,0x3F,0xFE,0x03,0x38,0xF6,0x03,0x0C,0xBA,0x03,0x0E,0x00,0x00,0x06,0xF6,0x05,0x70,0xFD,0x05,0xE0,0xB0,0x73,0x06,0xFE,0x03,0xF0,0xB0,0x03,0x80,0xF7,0x09,0x7C,0x00,0x00,0x7F,0x00,0x00,0xFF,0x00,0x00,0xF8,0x00,0x00,0x18,0xA2,0x03,0x0E,0xFF,0x03,0x00,0xB0,0x0D,0xF3,0xEB,0x03,0x3F,0xF0,0x03,0xFF,0xB0,0x67,0x00,0x00,0x00,0x01,0xCB,0x03,0xFF,0xB0,0x0B,0x30,0x00,0x00,0x20,0xFC,0x05,0x18,0x00,0x00,0x1C,0x00,0x00,0x0F,0xFF,0x03,0x00,0xB0,0x0D,0x3F,0x60,0x05,0x00,0xFF,0x03,0xC0,0xB0,0x67,0x03,0xC7,0x03,0x7F,0xF8,0x0B,0x20,0xAC,0x09,0x70,0x5F,0x03,0xFE,0xB0,0x0F,0x0F,0x01,0x05,0x00,0xB0,0x6B,0x0C,0xF4,0x17,0x60,0xBF,0x0B,0x60,0xB7,0x09,0x04,0xA3,0x05,0x00,0xFF,0x03,0x80,0xB0,0x67,0x00,0xCC,0x69,0x00,0x97,0xD3,0x00,0x81,0xFF,0x00,0x81,0xFF,0x00,0x81,0xFF,0x00,0xEB,0x2B,0x00
};unzip_TypeDef unzip;
ENCODE_TypeDef encode_str[MAX_STRUCT_LEN]; void new_pic(uint16_t type_len, const unsigned char *pic){for(uint16_t i=0;i<type_len/3;i++){encode_str[i].off = ((pic[i*3+1]&0x01)<<8 | pic[i*3])&0x1ff;encode_str[i].len = (pic[i*3+1]>>1)&0x7f;encode_str[i].ch = pic[i*3+2];}
}void update_slide(int strLen, unsigned char *slide){memset(unzip.slide, 0, SLIDE_LEN);	//清除缓存 for(int i=0;i<SLIDE_LEN;i++){	//更新滑动窗口 if(strLen-i >= 0) unzip.slide[SLIDE_LEN-i] = unzip.str[strLen-i]; }
}void decode(uint16_t type_len, const unsigned char *pic){int i,j;int struct_len = 0;unzip.strLen = 0;new_pic(type_len, pic);memset(unzip.str, 0, MAX_STRING_LEN);struct_len = type_len/3;//sizeof(encode_str)/sizeof(encode_str[0]);	//计算多少组压缩数据 for(i=0;i<struct_len;i++){			//循环解析压缩的数据 update_slide(unzip.strLen, unzip.slide);	//更新滑动窗口 for(j=0;j<encode_str[i].len;j++){//根据字典解析出压缩的字符unzip.str[unzip.strLen++] = unzip.slide[encode_str[i].off+j];//根据字典、len、offset解析原字符 }unzip.str[unzip.strLen++] = encode_str[i].ch;		//压缩数据后面的字符 }
}int main(void){uint16_t i;decode(sizeof(table)/sizeof(table[0]), table);printf("zip %d bytes\n",sizeof(table)/sizeof(table[0]));for( i=0;i<param.strLen;i++)printf("%02x ",param.str[i]);printf("\nunzip: %d bytes\n",param.strLen);
}

运行结果

也可以拿其他压缩数据试试

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