compress.cpp

压缩解压压 缩解压压 缩解压压缩解压

#include <iostream>
#include <stdlib.h>

using namespace std;
    int total;
    int root_pos;

   //Huffman树的节点结构
   typedef struct
   {
      unsigned long  weight;
      short left, right, parent;
      unsigned short bit_code;        // max 16 bits code
      short code_length;
   } hufnode;
   hufnode  huftree[511];
   
     FILE *infile, *outfile;
     char *infile_name;
     char outfile_name[20];
     
int main(int argc, char *argv[])
    {
        infile_name = argv[1];                                                  //打开文件
        strcpy(outfile_name, argv[2]);
        if ((infile=fopen(infile_name, "rb")) == NULL)   
        {
            printf("Unable to open input file %s.\n", infile_name);
            return 1;
        }

        while (!feof(infile))                                                   //统计字符的出现次数
        {
            unsigned char c = fgetc(infile);
            if (feof(infile))
            continue;
            ++total;
            ++huftree[c].weight; 
        }
        fclose(infile);  
    
    void create_code(short i ) ;
    
    if ((outfile=fopen(outfile_name, "wb")) == NULL)                          //写头部格式信息
            {
                        printf("Unable to create %s.\n", outfile_name);
                        return 1;
            }
            fwrite((void *)infile_name, sizeof(char),20,outfile);   
            fwrite((void *)&total, sizeof(long),1,outfile); 
            fwrite((void *)&root_pos, sizeof(short),1,outfile);
            fwrite((void *)&huftree, sizeof(hufnode),511,outfile);  
            return 0;
            
    void output_bits(unsigned int bit_code, int code_length);      
    system("PAUSE");	
    return 0;  
    }
  
        void create_code(short  i )                                             //构建字符的Huffman编码
        {
                short current = i;
                short parent = huftree[i].parent;
                unsigned short code_length = 0;
                short code = 0;
                while(parent)  
                {
                        code_length++;
                        if(huftree[parent].left == current)   // left 1, right 0 
                        code |= 1<<(code_length-1);
                        current = parent;
                        parent = huftree[current].parent;    
                }
                huftree[i].code_length = code_length;    
                huftree[i].bit_code = code;    
        } 
    
       void output_bits(unsigned int bit_code, int code_length)                 //输出Huffman编码
       {
              static unsigned char buffer = 0;
              static unsigned char bits_used = 0;
              bit_code <<= (16 - code_length);        
              for(short i=0; i<code_length; i++) 
              {
                      buffer <<= 1;                        
                      buffer |= ((bit_code & 0x8000) !=0); 
                      bit_code <<= 1;    
                      bits_used++;                      
                      if(bits_used == 8) 
                      {       fputc(buffer,outfile);
                              bits_used = 0;         
                              buffer    = 0; 
                      }    
              }    
       }