二进制算术编码器的C语言实现

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


#define n 100
/**/
void main(){
/*从文件中获取,temp用于中间值，i迭代，0和1的总个数，n所需最小信息量n1*/
    int temp;
    int i,m;
    int buf[n];
    int n0,n1;
    double p0,p1;
    FILE * fp;
    i=0;m=0;
    n0=n1=0;
    if((fp=fopen("source1.dat","r"))==NULL)
    {
        printf("open erro!\n");
    }
    else
    { 
        while (!feof(fp))
        {
             fscanf(fp,"%d",&temp);
             buf[i]=temp;
             printf("%d",buf[i]);
             i++;
             m++;
        }
    }
    printf("\ntotal number is : %d\n",m);
  
    /*计算0和1的数目n0和n1以及p0和p1*/
    for(i=0;i<m;i++){
        if(buf[i]==0) n0++;
    }
    n1=m-n0;
    p0=(double)n0/m;p1=1-p0;
    printf("n0=%d,n1=%d,p0=%f,p1=%f\n",n0,n1,p0,p1);

    /*计算信息熵*/
    double ex;
    int lx;
    ex=m*(p0*log(1/p0)/log(2)+p1*log(1/p1)/log(2));
    printf("至少需要%lf位编码\n",ex);
    lx=ceil(ex+1);
    printf("至少需要%d位编码\n",lx);


    /*编码过程*/
    double low=0.0;
    double high=1.0;
    double d=high-low;
    double dec=0.0;
    double x=0.0;
    int codeword[lx];
    for(i=0;i<m;i++){
        if(buf[i]==1){
            low = low + d*p0;
            d=high-low;
        }
        else if(buf [i]==0){
            high= low+d*p0;
            d=high-low;
        } 
    }
    printf("下限是：%.15f 上限是：%.15f\n",low,high);
    dec=(low+high)/2.0;
    printf("\n选取的小数为：%.15f\n",dec);
    for(i=0;i<lx;i++){
        dec*=2;
        if(dec>1.0){
            dec-=1;
            codeword[i]=1;
        }else{
            codeword[i]=0;
        }
    }
    printf("编码为：\n");
    for(i=0;i<lx;i++)
    {
        printf("%d",codeword[i]);
    }
    printf("\n编码结束\n");
    for(i=0;i<lx;i++)
    {
        x+=codeword[i]*pow(2,(-i-1));
    }
    printf("恢复的小数为：%.17f\n",x);
    if((x>low)&&(x<high))printf("\n恢复的小数仍在允许区间，成功！\n");
  
    /*解码过程*/
    low=0.0;
    high=1.0;
    d=high-low;
    double divideLine=p0;
    int decodeWord[m];
    for(i=0;i<m;i++){
        if(x>divideLine){
            decodeWord[i]=1;
            low+=d*p0;
        }
        else{
            decodeWord[i]=0.0;
            high=low+d*p0;
        }
        d=high-low;
        divideLine=low+d*p0;
    }
    for(i=0;i<m;i++){
          printf("%d",decodeWord[i]);
    }
    for(i=0;i<m;i++){
          if(buf[i]!=decodeWord[i])printf("第%d位有误",i);
    }
    printf("\n没有任何错误!\n");
}