以下是C語言實(shí)現(xiàn)無損壓縮算法的代碼：
#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[256] = {0};
unsigned int data_num;
unsigned int code_size;
unsigned int last_bit;
void FrequencyCount(unsigned char*);//頻率統(tǒng)計(jì)
void HuffSelect(HuffNode*, int, int*, int*); //從結(jié)點(diǎn)中選出權(quán)最小的兩個節(jié)點(diǎn)
void HuffmanCodeTable(HuffNode*, HuffCode*); //構(gòu)造huffman樹，生成huffman編碼表
void HuffmanCompress(unsigned char*, unsigned char *, HuffCode*); //壓縮數(shù)據(jù)
void BitPrint(unsigned char*);//按位打印結(jié)果，用于調(diào)試
void main()
{
int i, j, loop;//variable for loop
HuffNode hfdata[2*DNUM] = {{0, 0, 0, 0, 0}}; //Huffman node
HuffCode code_table[256] = {{0, 0}};//code table will be searched by subscript
unsigned char hfcode[2*DNUM];//output code
time_t time1, time2;
/* unsigned char pixel[DNUM] = {
1,2,3,4, 1,2,3,4, 1,2,3,4, 1,1,1,1};
*/
/* unsigned char pixel[DNUM] = {
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[DNUM] = { //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[DNUM] = {
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[i]) {
hfdata[j].weight = fCount[i];
hfdata[j++].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[j].data=0;
hfdata[j].lchild=0;
hfdata[j].parent=0;
hfdata[j].rchild=0;
hfdata[j].weight=0;
}
}
time2 = time(NULL);
//conclude
printf("n哈夫曼編碼壓縮圖塊，壓縮報(bào)告n華中科技大學(xué)力學(xué)系：李美之n");
printf("n◎源數(shù)據(jù)（%d字節(jié)）:n ", DNUM);
for (i=0; i<DNUM; i++) {
printf(i%8==7 ? "%02Xn " : "%02X ", pixel[i]);
}
printf("n◎壓縮數(shù)據(jù)（%d字節(jié)）:n ", code_size);
for (i=0; i<code_size; i++) {
printf(i%8==7 ? "%02Xn " : "%02X ", hfcode[i]);
}
//打印碼表
printf("nn◎碼表－編碼字典（%d項(xiàng)）n", data_num);
for (i=0; i<256; i++) {
if (code_table[i].codelength) {
printf("%3d|%02X: ", i, i);
for (j=0; j<code_table[i].codelength; j++) {
printf("%d", ((code_table[i].code << j)&0x80)>>7);
}
printf("t");
}
}
printf("nn◎壓縮率：%2.0f%% t壓縮時間：%.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[i];
for (j=0; j<8; j++) {
printf("%d", ((thebyte<<j)&0x80)>>7);
}
}
if (last_bit == 7) {
endbit = -1;
}
thebyte = hfcode[i];
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[i];
curcode = (code_table[value]).code;
curlength = (code_table[value]).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[ptbyte++] = thebyte;
thebyte = 0;
curbit = 7;
bytenum ++;
}
}
}
//think about which bit is the end
if (curbit != 7) {
hfcode[ptbyte] = 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[min1].parent = i+1;
hfdata[min2].parent = i+1;
hfdata[i+1].lchild = min1;
hfdata[i+1].rchild = min2;
hfdata[i+1].weight = hfdata[min1].weight + hfdata[min2].weight;
}
//generate huffman code
//i present the i th code, j present from leaf to root in huffman tree
//hfdata[i].data (0:255) is a byte number
//編碼從葉讀到根，按位從高往低壓入一個字節(jié)，讀編碼從左向右
for (i=1; i<=data_num; i++) {
curcode = 0;
curlength = 0;
for (j=i, p=hfdata[j].parent; p!=0; j=p, p=hfdata[j].parent) {
curlength ++;
if (j==hfdata[p].lchild) curcode >>= 1;
else curcode = (curcode >> 1) | 0x80; //0x80 = 128 = B1000 0000
}
code_table[hfdata[i].data].code = curcode;
code_table[hfdata[i].data].codelength = curlength;
}
}
void HuffSelect(HuffNode *hfdata, int end, int *min1, int *min2)
{
int i; //variable for loop
int s1, s2;
HuffNode wath[30];
for (i=0; i<30; i++) {
wath[i] = hfdata[i];
}
s1 = s2 = 1;
while (hfdata[s1].parent) {
s1++;
}
for (i=2; i<=end; i++) {
if (hfdata[i].parent == 0 && hfdata[i].weight < hfdata[s1].weight) {
s1 = i;
}
}
while (hfdata[s2].parent || s1 == s2) {
s2++;
}
for (i=1; i<=end; i++) {
if (hfdata[i].parent ==0 && hfdata[i].weight < hfdata[s2].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)] ++;
}
}
來源:向明天進(jìn)軍0次
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