哈夫曼算法（haffman）实现压缩和解压缩-C语言实现

/*
* =====================================================================================
*
* Filename: haffman.c
*
* Description: huffman coder decoder
*
* Version: 1.0
* Created:
* Revision: none
* Compiler: gcc
*
*
* =====================================================================================
*/

#include <unistd.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

#define N 256
#define Maxsize 80
#define SOME 1
#define Empty 0
#define FULL -1

typedef unsigned long int WeightType;
typedef unsigned char MyType;
typedef struct    //哈夫曼树
{
MyType ch;    //存字符
WeightType weight;    /* 用来存放各个结点的权值 */
int parent, LChild, RChild;    /*指向双亲、孩子结点的指针 */
} HTNode;

typedef struct    //队列
{
int tag;
int front;
int rear;
MyType length;
char elem[Maxsize];
} SeqQueue;

void writeFile();
void printHFM(HTNode * ht, int n);
void code(char **hc, int n, unsigned char *ch);

int InitQueue(SeqQueue * Q)
{
if (!Q)
return 1;
Q->tag = Empty;
Q->front = Q->rear = 0;
Q->length = 0;

return 0;
}

int In_seqQueue(SeqQueue * Q, char x)
{
if (Q->front == Q->rear && Q->tag == SOME)
return FULL;    //full

Q->elem[Q->rear] = x;    // printf("in = %c",x);
Q->rear = (Q->rear + 1) % Maxsize;
Q->length++;
Q->tag = SOME;
return SOME;
}

int Out_Queue(SeqQueue * Q, char *x)
{
if (Q->tag == Empty)
return Empty;

*x = Q->elem[Q->front];
Q->length--;
Q->front = (Q->front + 1) % Maxsize;

if (Q->front == Q->rear)
Q->tag = Empty;

return SOME;
}

/* ------------------以上是队列的操作------------------------- */

void SelectMinTree(HTNode * ht, int n, int *k)
{
int i, temp;
WeightType min;

// printf(" Selecting……n= %d",n);
for (i = 0; i <= n; i++) {
if (0 == ht[i].parent) {
min = ht[i].weight;    //init min
temp = i;
break;
}
}
for (i++; i <= n; i++) {
if (0 == ht[i].parent && ht[i].weight < min) {
min = ht[i].weight;
temp = i;
}
}
*k = temp;
}

// 对哈夫曼树排序，并统计叶子数量
int SortTree(HTNode * ht)
{
short i, j;
HTNode tmp;

for (i = N - 1; i >= 0; i--) {
for (j = 0; j < i; j++)
if (ht[j].weight < ht[j + 1].weight) {
tmp = ht[j];
ht[j] = ht[j + 1];
ht[j + 1] = tmp;
}
}
for (i = 0; i < N; i++)
if (0 == ht[i].weight)
return i;
return i;    //返回叶子个数
}

//求哈夫曼0-1字符编码表
char **CrtHuffmanCode(HTNode * ht, short LeafNum)
/*从叶子结点到根，逆向求每个叶子结点对应的哈夫曼编码*/
{
char *cd, **hc;    //容器
int i, start, p, last;

hc = (char **)malloc((LeafNum) * sizeof(char *));    /*分配n个编码的头指针 */

if (1 == LeafNum)    //只有一个叶子节点时
{
hc[0] = (char *)malloc((LeafNum + 1) * sizeof(char));
strcpy(hc[0], "0");
return hc;
}

cd = (char *)malloc((LeafNum + 1) * sizeof(char));    /*分配求当前编码的工作空间 */
cd[LeafNum] = ‘\0‘;    /*从右向左逐位存放编码，首先存放编码结束符 */
for (i = 0; i < LeafNum; i++) {    /*求n个叶子结点对应的哈夫曼编码 */
start = LeafNum;    /*初始化编码起始指针 */
last = i;
for (p = ht[i].parent; p != 0; p = ht[p].parent) {    /*从叶子到根结点求编码 */
if (ht[p].LChild == last)
cd[--start] = ‘0‘;    /*左分支标0 */
else
cd[--start] = ‘1‘;    /*右分支标1 */
last = p;
}
hc[i] = (char *)malloc((LeafNum - start) * sizeof(char));    /*为第i个编码分配空间 */
strcpy(hc[i], &cd[start]);
//
printf("%3d号 %3c 码长:%2d;编码:%s\n", ht[i].ch, ht[i].ch,
LeafNum - start, &cd[start]);
}    //getchar();
free(cd);    // Printcode(hc,n);
return hc;
}

HTNode *CreatHFM(FILE * fp, short *n, WeightType * FileLength)
{
HTNode *ht = NULL;
int i, m, s1, s2;
MyType ch;

ht = (HTNode *)malloc(2 * N * sizeof(HTNode));
if (!ht)
exit(1);

for (i = 0; i < N; i++) {
ht[i].weight = 0;
ht[i].ch = (MyType)i;    /*1-n号ch 为字符，初始化 */
}

for (*FileLength = 0; !feof(fp); ++(*FileLength)) {
ch = fgetc(fp);    //fread(&ch,1,1,fp);
ht[ch].weight++;    //printf("ht[%c].weight= %ld\n",0,ht[0].weight);
}
--(*FileLength);    //去掉文件结束后的长度
*n = SortTree(ht);
m = *n * 2 - 1;    //free(&ht[m+1]);
//printf("叶子个数= %d\n",*n);//getchar();
if (1 == *n) {
ht[0].parent = 1;
return ht;
}
else if (0 > *n)
return NULL;

for (i = m - 1; i >= 0; i--) {
ht[i].LChild = 0;
ht[i].parent = 0;
ht[i].RChild = 0;
}
/* ------------初始化完毕！对应算法步骤1--------- */
for (i = *n; i < m; i++)    //创建非叶子结点,建哈夫曼树
{    //在ht[0]~ht[i-1]的范围内选择两个parent为0且weight最小的结点，其序号分别赋值给s1、s2返回
SelectMinTree(ht, i - 1, &s1);
ht[s1].parent = i;
ht[i].LChild = s1;

SelectMinTree(ht, i - 1, &s2);
ht[s2].parent = i;
ht[i].RChild = s2;

ht[i].weight = ht[s1].weight + ht[s2].weight;
}    /*哈夫曼树建立完毕 */// puts(" over^_^");

return ht;
}

//从队列里取8个字符（0、1），转换成一个字节
MyType GetBits(SeqQueue * Q)
{
MyType i, bits = 0;
char x;

for (i = 0; i < 8; i++) {
if (Out_Queue(Q, &x) != Empty) {    //printf("%c",x);
if (‘0‘ == x)
bits = bits << 1;
else
bits = (bits << 1) | 1;
}
else
break;
}    //printf(" bits=%d\n",bits);puts("");

return bits;
}

//求最长（最短）编码长度
void
MaxMinLength(FILE * File, HTNode * ht, char **hc, short NLeaf, MyType * Max,
MyType * Min)
{
int i;
MyType length;

*Max = *Min = strlen(hc[0]);
for (i = 0; i < NLeaf; i++) {
length = strlen(hc[i]);
fwrite(&ht[i].ch, sizeof(MyType), 1, File);    //字符和对应的
fwrite(&length, sizeof(MyType), 1, File);    //编码长度写进文件
if (length > *Max)
*Max = length;
if (length < *Min)
*Min = length;
}
}

//把出现过的字符编码表经过压缩写进文件
short CodeToFile(FILE * fp, char **hc, short n, SeqQueue * Q, MyType * length)
{
int i;
char *p;
MyType j, bits;
short count = 0;

for (i = 0; i < n; i++)    // 将n个叶子压缩并写入文件
{
for (p = hc[i]; ‘\0‘ != *p; p++)
In_seqQueue(Q, *p);

while (Q->length > 8) {    // puts("出队");
bits = GetBits(Q);    //出队8个元素
fputc(bits, fp);    //fwrite(&bits,sizeof(char),1,fp);
//printf("压字符 %c\n",bits);
count++;
}
}    // printf("码字最后剩: %d\n",Q->length);

*length = Q->length;
i = 8 - *length;
bits = GetBits(Q);    //取8个如果队不空
for (j = 0; j < i; j++)
bits = bits << 1;    //printf("压 字符 %c\n",bits);
fputc(bits, fp);    //fwrite(&bits,sizeof(char),1,fp);
count++;    //printf(" 指 针 在%d \n",ftell(fp));

InitQueue(Q);
return count;
}

//压缩
void Compress()
{
char desFile[80], rename[80];
MyType maxLen, minLen, ch, bits, n, finalLength;
int i;
short LeafNum, codeNum;
WeightType count = 0, Length = 0, FileLength;
FILE *fp, *compressFile;
SeqQueue *Q;
HTNode *ht = NULL;
char **hc = NULL, **Map = NULL, *p;

printf("filename to be compressed:");
scanf("%s", desFile);
//getchar();//fflush(stdin);//清空输入缓冲区域

printf("filename after compressed:");
scanf("%s", rename);
if (‘\0‘ == rename[0]) {
printf("输入不能为空，请重新输入:");
scanf("%s", rename);
}

compressFile = fopen(rename, "wb");
fp = fopen(desFile, "rb");    //原文件

if (!fp || !compressFile) {
puts("Cannot open file.");
return;
}

ht = CreatHFM(fp, &LeafNum, &FileLength);    //创建哈夫曼树,统计叶子个数和原文件长度
if (!FileLength) {    // printf("文件为空，无须压缩...");
fclose(fp);
fclose(compressFile);
free(ht);
return;
}
Q = (SeqQueue *)malloc(sizeof(SeqQueue));
InitQueue(Q);    //SEEK_SET:文件开头 SEEK_CUR:当前位置 SEEK_END:文件结尾
hc = CrtHuffmanCode(ht, LeafNum);    //取得哈夫曼0、1编码,hc的长度为LeafNum
//Map为了取编码好定位，再建立全部(256个)//
Map = (char **)malloc(N * sizeof(char *));    //字符编码表
if (!Map) {
puts("申请空间失败");
return;
}

for (i = 0; i < N; i++)    //初始化
Map[i] = NULL;

for (i = 0; i < LeafNum; i++)    // 定位，编码指针数组Map[256]
Map[(int)(ht[i].ch)] = hc[i];

fseek(compressFile, sizeof(WeightType) + sizeof(short) + 6 * sizeof(MyType), SEEK_SET);    //先占个位置
//先占个位置,等下填压缩叶子编码剩几个和最长编码长//getchar();

MaxMinLength(compressFile, ht, hc, LeafNum, &maxLen, &minLen);    //获得最长码串长度,顺便填写字符对应编码长
// for(i = 0;i < LeafNum;i++)
// if(ht[i].ch == (MyType)1)
// printf("char %c %s\n",ht[i].ch,hc[i]);

free(ht);    //getchar();printf("最长码串长度: %d\n",MaxCode);printf("ftell = %d\n",ftell(compressFile));
codeNum = CodeToFile(compressFile, hc, LeafNum, Q, &finalLength);    //把字符转成其二进制编码写入文件,返回压成多少个

rewind(compressFile);    //使文件指针移到开始printf("ftelll = %d\n",ftell(compressFile));
fseek(compressFile, sizeof(WeightType) + sizeof(MyType), SEEK_SET);
fwrite(&LeafNum, sizeof(short), 1, compressFile);    //写入叶子个数
fwrite(&maxLen, sizeof(MyType), 1, compressFile);    //最长码串长度
fwrite(&minLen, sizeof(MyType), 1, compressFile);    //最短码串长度
//printf("MaxLen %d Min %d ftell = %d\n",maxLen,minLen,ftell(compressFile));getchar();
fwrite(&codeNum, sizeof(short), 1, compressFile);    //填写叶子编码压多少个
fwrite(&finalLength, sizeof(MyType), 1, compressFile);    //最后剩
//printf("叶子共压：%d个,最后剩%d个\n\n",codeNum,finalLength);

fseek(compressFile, 2 * LeafNum * sizeof(MyType) + codeNum, SEEK_CUR);
//printf("开始正文ftell= %d 原文长%d\n",ftell(compressFile),FileLength);getchar();
fseek(fp, 0, SEEK_SET);
printf("Please wait a minute,compressing...");

while (count < FileLength) {
ch = fgetc(fp);    //fread(&ch,sizeof(MyType),1,fp);
++count;    // printf("Read读 : %c 值 %d %s\n",ch,ch,Map[ch]);
for (p = Map[ch]; *p != ‘\0‘; p++)
In_seqQueue(Q, *p);
//printf("\nQlength: %d\n",Q->length);

while (Q->length > 8)    // printf("OutQueue: ");
{
bits = GetBits(Q);    //出队8个元素,合成一个字节
fputc(bits, compressFile);    //fwrite(&bits,1,1,compressFile);
Length++;    // printf("压：%c\n",bits);
}
}    //end of while
//最后一个bits ;
finalLength = Q->length;    //printf("最后剩Qlength:%d\n",Q->length);
n = 8 - finalLength;
bits = GetBits(Q);
//printf("最后Qlength:%d\n",Q->length);
for (i = 0; i < n; i++)
bits = bits << 1;    //以‘0’补
//fputc(bits,compressFile);
fwrite(&bits, sizeof(MyType), 1, compressFile);    //printf("\nfinal压：%c\n",bits);
Length++;

rewind(compressFile);    //原文件长fwrite(&FileLength,sizeof(WeightType),1,compressFile);
fwrite(&Length, sizeof(WeightType), 1, compressFile);    //压缩后的长
fwrite(&finalLength, sizeof(char), 1, compressFile);    //最后的串长

Length = Length + 12 + codeNum;    //printf("原文件长 %ld;压缩后 %ld\n",FileLength,Length);

if (Length >= FileLength)
puts("\nCompression rate: 0.0%");
else
printf("\nCompression rate: %.2lf%c\n",
(double)((FileLength -
Length) / (double)FileLength) * 100.0, ‘%‘);

fclose(fp);
fclose(compressFile);
free(Q);
free(hc);
free(Map);
}

//把读出的字符，转换成8个0、1字符串并入队
void ToQueue(SeqQueue * Q, MyType ch)
{
int i;
MyType temp;

for (i = 0; i < 8; i++) {
temp = ch << i;
temp = temp >> 7;
if (1 == temp)
In_seqQueue(Q, ‘1‘);    //printf("1");
else
In_seqQueue(Q, ‘0‘);    //printf("0");
}    //puts("");
}

//解压缩
void UnCompress()
{
MyType *str, MaxLength, MinLength, ch, *num, finalLength = 0, final = 0;
FILE *cf, *uf;
short NLeaf, Ncom;
char CName[N], UName[N], **hc, *p, x, *buf;
SeqQueue *Q = NULL;
int i, j;
WeightType srcLen = 0, thisFile = 0;

fflush(stdin);    //清空输入缓冲区域
printf("filename to be uncompressed:");
scanf("%s", CName);
if (CName[0] == ‘\0‘) {
printf("try again:");
scanf("%s", CName);
fflush(stdin);
}
fflush(stdin);    //清空输入缓冲区域
printf("filename after uncompressed:");
scanf("%s", UName);
if (UName[0] == ‘\0‘) {
printf("try again:");
scanf("%s", UName);
}

cf = fopen(CName, "rb");
uf = fopen(UName, "wb");
if (!cf || !uf) {
puts("Cannot open files.");
return;
}

fread(&srcLen, sizeof(WeightType), 1, cf);    //printf("压后文件长：%ld\n",srcLen);
fread(&finalLength, 1, 1, cf);    // printf("原文件压剩:%d个\n",finalLength);
fread(&NLeaf, sizeof(short), 1, cf);    //printf("叶子:%d个\n",NLeaf);
fread(&MaxLength, sizeof(MyType), 1, cf);
fread(&MinLength, sizeof(MyType), 1, cf);
//printf("MaxLength = %d;minLen= %d,Leaf= %d\n",MaxLength,MinLength,NLeaf);getchar();
Q = (SeqQueue *)malloc(sizeof(SeqQueue));

buf = (char *)malloc((2 + MaxLength * sizeof(char)));
str = (MyType *)malloc(NLeaf * sizeof(MyType));
num = (MyType *)malloc(NLeaf * sizeof(MyType));
//压缩叶子数量x和最后剩长
if (!Q || !str || !num || !buf) {
puts("Memery error.");
exit(1);
}
InitQueue(Q);    //初始化

fread(&Ncom, sizeof(short), 1, cf);
fread(&final, sizeof(MyType), 1, cf);

for (i = 0; i < NLeaf; i++)    //读取叶子及其码长
{
fread(&str[i], sizeof(MyType), 1, cf);
fread(&num[i], sizeof(MyType), 1, cf);
//printf("chars= %c;num= %d\n",Chars[i],CHlength[i]);
}
//printf("read ftell= %d\n",ftell(cf));//getchar();
// printf("\n叶子码字压缩后%d个,最后剩%d个\n",Ncom,final);

hc = (char **)malloc((NLeaf) * sizeof(char *));    //hc为编码表的指针数组
if (!hc)
exit(1);

--Ncom;    //printf("开始取叶子编码ftell = %d Ncom=%d\n",ftell(cf),Ncom);
for (j = i = 0; i < Ncom; i++) {
ch = fgetc(cf);    //fread(&ch,1,1,cf);
ToQueue(Q, ch);    //printf("Q->Len= %d\n",Q->length);
while (Q->length > MaxLength) {
hc[j] = p = (char *)malloc(1 + num[j]);
for (ch = 0; ch < num[j]; ch++) {
Out_Queue(Q, &x);
*p++ = x;
}
*p = ‘\0‘;    //printf("%c编 码%s\n",str[j],hc[j]);
j++;
}
}
ch = fgetc(cf);    //fread(&ch,1,1,cf);//最后一个
ToQueue(Q, ch);
final = 8 - final;
while (Q->length > final) {
p = hc[j] = (char *)malloc(1 + num[j]);
for (ch = 0; ch < num[j]; ch++) {
Out_Queue(Q, &x);
*p++ = x;
}
*p = ‘\0‘;    //printf("%c编码%s\n",str[j],hc[j]);getchar();
j++;
}

InitQueue(Q);
--srcLen;
--MinLength;
//printf("开始解压正文%d ,压后长= %d\n",ftell(cf),srcLen);getchar();
printf("Please wait a minute,uncompressing...");
while (thisFile < srcLen) {
// printf("QLength= %d\n",Q->length);
ch = fgetc(cf);    //fread(&ch,sizeof(MyType),1,cf);
ToQueue(Q, ch);
thisFile++;    // printf("char:%c",ch);
//完了后队列长于码串的最大值

while (Q->length > MaxLength) {
for (i = 0; i < MinLength; i++) {
Out_Queue(Q, &x);
buf[i] = x;
}
for (; i < MaxLength; i++) {
Out_Queue(Q, &x);
buf[i] = x;
buf[i + 1] = ‘\0‘;
for (j = 0; j < NLeaf; j++) {
if (i + 1 == num[j]
&& 0 == strcmp(hc[j], buf)) {
ch = str[j];    //printf("出队 %s\n",buf);
fputc(ch, uf);    //fwrite(&ch,1,1,uf);////printf("解 出：%c\n",ch);
break;
}
}
if (j < NLeaf)
break;
}
}    //while MaxLength
}

ch = fgetc(cf);    //fread(&ch,1,1,cf);//读取最后一个压缩字getchar();
ToQueue(Q, ch);

finalLength = 8 - finalLength;
while (Q->length > finalLength) {
for (i = 0; i < MinLength; i++) {
Out_Queue(Q, &x);
buf[i] = x;
}
for (; i < MaxLength; i++) {
Out_Queue(Q, &x);
buf[i] = x;
buf[i + 1] = ‘\0‘;
for (j = 0; j < NLeaf; j++) {
if (i + 1 == num[j] && 0 == strcmp(hc[j], buf)) {
ch = str[j];    //printf("出 %s\n",buf);
fputc(ch, uf);    //fwrite(&ch,1,1,uf);//printf("解 出：%c\n",ch);
break;
}
}
if (j < NLeaf)
break;
}
}
//printf("Q->length= %d\n",Q->length);printf("ftell= %d\n",ftell(uf));
free(Q);
free(str);
free(num);
free(hc);
fclose(uf);
fclose(cf);
}

int main(int argc, char *argv[])
{
char choice, blank[] = " ";
// writeFile();
system("color 8a");
while (1) {
system("clear");    //清屏
puts(" * * * *Welcome use huffman encoder\\decoder* * *");
puts(" **********************^_^***********************");
puts(" * *");
printf(" * %s 1 ]. Compress %s*\n", blank, blank);
puts(" * *");
printf(" * %s 2 ]. Uncompress%s *\n", blank, blank);
puts(" * *");
printf(" * %s 3 ]. Exit ^_^ %s *\n", blank, blank);
puts(" * *");
puts(" ************************************************");
printf
(" (Apply to text file) Copyright 2011 By Bocai\n");
printf(" Choose (1 to 3):");
choice = getchar();

puts("");
getchar();
fflush(stdin);    //清空输入缓冲区域，否则键入的回车符将作为程序结尾处的scanf输入，此函数在stdio.h中
switch (choice) {
case ‘1‘:
Compress();
printf("Press Enter to continue...");
getchar();
break;
case ‘2‘:
UnCompress();
printf("\nPress Enter to continue...");
getchar();
break;
case ‘3‘:
return 0;
break;
}
}

return 0;
}

/*----------------------------END----------------------------------------*/