用C语言编写程序实现Zip或者Rar无损压缩算法
用C语言编写程序实现Zip或者Rar无损压缩算法2008-09-20 18:41本文详细介绍用C语言编写程序实现Zip或者Rar无损压缩算法 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ** *
*HUFF.C Huffman encode for multimedia application 8*8 pixel Ver 3 *
* *
*Ver 1: Complied in Borland Turbo C++ 3.0 *
*Ver 2: Complied in Microsoft Visual C++ 6.0 *
*Ver 3: Complied in Microsoft Visual C++ 6.0 *
* add code to print code table of the compression *
* print output message in Chinese *
* *
*by Lee Meitz, Solid Mechanics, Huazhong Univ of Sci and Tech *
*2001.11.15 - 2001.12.27 *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define DNUM 64 //define data number 8*8
#define LOOP 10000 //times of compression
typedef struct
{
unsigned short weight, data;
unsigned short parent, lchild, rchild;
} HuffNode;
typedef struct
{
unsigned char code;
unsigned short codelength;
} HuffCode;
unsigned int fCount = {0};
unsigned int data_num;
unsigned int code_size;
unsigned int last_bit;
void FrequencyCount(unsigned char*); //频率统计
void HuffSelect(HuffNode*, int, int*, int*); //从结点中选出权最小的两个节点
void HuffmanCodeTable(HuffNode*, HuffCode*); //构造huffman树，生成huffman编码表
void HuffmanCompress(unsigned char*, unsigned char *, HuffCode*); //压缩数据
void BitPrint(unsigned char*); //按位打印结果，用于调试
void main()
{
int i, j, loop; //variable for loop
HuffNode hfdata = {{0, 0, 0, 0, 0}}; //Huffman node
HuffCode code_table = {{0, 0}}; //code table will be searched by subscript
unsigned char hfcode; //output code
time_t time1, time2;
/* unsigned char pixel = {
1,2,3,4, 1,2,3,4, 1,2,3,4, 1,1,1,1};
*/
/* unsigned char pixel = {
139,144,149,153,155,155,155,155,
144,151,153,156,159,156,156,156,
150,155,160,163,158,156,156,156,
159,161,162,160,160,159,159,159,
159,160,161,162,162,155,155,155,
161,161,161,161,160,157,157,157,
162,162,161,163,162,157,157,157,
162,162,161,161,163,158,158,158};
*/
unsigned char pixel = { //random data
141, 101, 126, 111, 163, 112, 133, 156,
103, 144, 111, 176, 117, 120, 188, 187,
175, 164, 190, 156, 112, 179, 142, 119,
140, 111, 127, 186, 196, 190, 189, 127,
185, 103, 185, 110, 192, 139, 159, 104,
151, 193, 178, 198, 114, 170, 179, 149,
124, 149, 165, 108, 141, 176, 113, 164,
101, 140, 120, 126, 173, 189, 158, 184};
/* unsigned char pixel = {
202, 221, 159, 183, 41, 136, 247, 66,
146, 29, 101, 108, 45, 61, 210, 236,
90, 130, 54, 66, 132, 206, 119, 232,
184, 135, 96, 78, 120, 41, 231, 203,
150, 94, 172, 142, 122, 180, 150, 204,
232, 121, 180, 221, 3, 207, 115, 147,
72, 149, 169, 121, 76, 208, 235, 43,
107, 58, 0, 237, 197, 7, 210, 89};
*/
FrequencyCount(pixel);
time1 = time(NULL);
for (loop=0; loop<LOOP; loop++) {
//set huffman nodes data and weight, i=0:255, j=1:64
for (i=0, j=1, data_num=0; i<256; i++) {
if (fCount) {
hfdata.weight = fCount;
hfdata.data = i;
data_num ++;
}
}
//build huffman tree and generate huffman code table
HuffmanCodeTable(hfdata, code_table);
//compress source data to huffman code using code table
HuffmanCompress(pixel, hfcode, code_table);
//initial hfdata and code_table
for (j=0; j<2*DNUM; j++) {
hfdata.data=0;
hfdata.lchild=0;
hfdata.parent=0;
hfdata.rchild=0;
hfdata.weight=0;
}
}
time2 = time(NULL);
//conclude
printf("n哈夫曼编码压缩图块，压缩报告n华中科技大学力学系：李美之n");
printf("n◎源数据（%d字节）:n ", DNUM);
for (i=0; i<DNUM; i++) {
printf(i%8==7 ? "%02Xn " : "%02X ", pixel);
}
printf("n◎压缩数据（%d字节）:n ", code_size);
for (i=0; i<code_size; i++) {
printf(i%8==7 ? "%02Xn " : "%02X ", hfcode);
}
//打印码表
printf("nn◎码表－编码字典（%d项）n", data_num);
for (i=0; i<256; i++) {
if (code_table.codelength) {
printf("%3d|%02X: ", i, i);
for (j=0; j<code_table.codelength; j++) {
printf("%d", ((code_table.code << j)&0x80)>>7);
}
printf("t");
}
}
printf("nn◎压缩率：%2.0f%% t压缩时间：%.3f毫秒n",(float)code_size/DNUM * 100, 1E3*(time2-time1)/LOOP);
}
void BitPrint(unsigned char *hfcode)
{
int i, j;
int endbit = last_bit;
unsigned char thebyte;
for (i=0; i < code_size-1; i++) {
thebyte = hfcode;
for (j=0; j<8; j++) {
printf("%d", ((thebyte<<j)&0x80)>>7);
}
}
if (last_bit == 7) {
endbit = -1;
}
thebyte = hfcode;
for (j=7; j>endbit; j--) {
printf("%d", ((thebyte<<(7-j))&0x80)>>7);
}
}
void HuffmanCompress(unsigned char *pixel, unsigned char *hfcode, HuffCode * code_table)
{
int i, j;
int curbit=7; //current bit in _thebyte_
unsigned int bytenum=0; //number of destination code can also be position of byte processed in destination
unsigned int ptbyte=0; //position of byte processed in destination
unsigned int curlength; //code's length of _curcode_
unsigned char curcode; //current byte's huffman code
unsigned char thebyte=0; //destination byte write
unsigned char value; //current byte's value (pixel[])
//process every byte
for (i=0; i<DNUM; i++) {
value = pixel;
curcode = (code_table).code;
curlength = (code_table).codelength;
//move out every bit from curcode to destination
for (j=0;j<=curlength;j++) {
if ((curcode<<j)&0x80) {
thebyte |= (unsigned char)(0x01<<curbit);
}
curbit --;
if (curbit < 0) {
hfcode = thebyte;
thebyte = 0;
curbit = 7;
bytenum ++;
}
}
}
//think about which bit is the end
if (curbit != 7) {
hfcode = thebyte;
bytenum ++;
}
code_size = bytenum;
last_bit = curbit;
}
void HuffmanCodeTable(HuffNode *hfdata, HuffCode *code_table)
{
int i, j; //variable for loop
int tree_num = 2*data_num - 1; //node of huffman tree
int min1, min2; //two minimum weight
int p; //the id of parent node
unsigned char curcode; //current code being processing
int curlength; //current code's length
//build huffman tree
for (i=data_num; i<tree_num; i++) {
HuffSelect(hfdata, i, &min1, &min2);
hfdata.parent = i+1;
hfdata.parent = i+1;
hfdata.lchild = min1;
hfdata.rchild = min2;
hfdata.weight = hfdata.weight + hfdata.weight;
}
//generate huffman code
//i present the i th code, j present from leaf to root in huffman tree
//hfdata.data (0:255) is a byte number
//编码从叶读到根，按位从高往低压入一个字节，读编码从左向右
for (i=1; i<=data_num; i++) {
curcode = 0;
curlength = 0;
for (j=i, p=hfdata.parent; p!=0; j=p, p=hfdata.parent) {
curlength ++;
if (j==hfdata.lchild) curcode >>= 1;
else curcode = (curcode >> 1) | 0x80; //0x80 = 128 = B1000 0000
}
code_table.data].code = curcode;
code_table.data].codelength = curlength;
}
}
void HuffSelect(HuffNode *hfdata, int end, int *min1, int *min2)
{
int i; //variable for loop
int s1, s2;
HuffNode wath;
for (i=0; i<30; i++) {
wath = hfdata;
}
s1 = s2 = 1;
while (hfdata.parent) {
s1++;
}
for (i=2; i<=end; i++) {
if (hfdata.parent == 0 && hfdata.weight < hfdata.weight) {
s1 = i;
}
}
while (hfdata.parent || s1 == s2) {
s2++;
}
for (i=1; i<=end; i++) {
if (hfdata.parent ==0 && hfdata.weight < hfdata.weight && (i - s1)) {
s2 = i;
}
}
*min1 = s1;
*min2 = s2;
}
void FrequencyCount(unsigned char *chs)
{
int i;
for (i=0; i<DNUM; i++) {
fCount[*(chs+i)] ++;
}
} mark 太晚了，标记，明天再细看。 jh 看看 mark mark mark mark 记号 能先讲下原理吗，这样看着头大哦。 mark 传闻中的哈夫曼编码…… MARK mark
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