bluet2-3fecinterface.c

蓝牙模块的2-3FEC接口函数(在CCS环境下编译通过) config文件自己编写

    #include "config.h"
      /*  code_bit  */
      uint16 
      g[15]={0x1,0x2,0x4,0x8,0x10,0x20,0x40,0x80,0x100,0x200,0x365,0x1AF,0x35E,0x1D9,0x3B2};
      void FEC_code(uint16 *code_in, uint16 *code_out, uint8 len)
      {
         uint8  i, j;
         uint16 a, val, code;
         uint16 mid[15];
         uint16 code_bit[15];
         
         for ( ; len > 0 ; len-- ) 
         {
             val = *code_in++;
             
          for(i=0;i<15;i++)
          {
             a = val&g[i];      
             for(j=0;j<10;j++)
          {
                mid[j] = a&1;
                a = a>>1;
          }
             code_bit[i] = mid[0];
             
             for(j=1;j<10;j++)
               code_bit[i] = code_bit[i]^mid[j];
          }
          code = 0;
          for(i=0;i<15;i++)
          {
              code |= (code_bit[i]<<i);
          }
          *code_out++ = code;
       }       
      }
      /* decode and correct */
      uint16 check[5]={0x765,0x9AF,0x135E,0x21D9,0x43B2};  /*the check array*/
      void FEC_decode(uint16 *code_in, uint16 *code_out, uint8 len)
      { 
        uint8  i, j;
        uint16 a, val, code;
        uint16 mid[15];
        uint16 code_bit[15];  
        uint16 check_out[5];
        uint16 errorflag,matchbit,matchflag,comparebit;
        
        for ( ; len > 0 ; len-- ) 
        {
           val = *code_in++; 
              
         a = val;
         for (i=0;i<15;i++)      /*change the data received into bits*/
         { 
         code_bit[i] = a&1;
            a = a>>1;
         }
         for(i=0;i<5;i++)        /*caculate the cheksum*/
         {  
         a = val&check[i];
            for(j=0;j<15;j++)    /*get every bit of a */
         {
            mid[j] = a&1;
            a=a>>1;
         }
            check_out[i] = mid[0];
            for(j=1;j<15;j++)
               check_out[i]=check_out[i]^mid[j]; /*add the bits in mode 2*/
         }
         i=0; 
         errorflag=0;  
         do 
         {
            if(check_out[i]==1) 
            { 
             errorflag=1; 
             i=5;
            }
            else 
             i++;
         }
         while (i<5);      /* check if the check is all 0 */
         if (errorflag==1)
         {   
            i=0;  
            matchbit=100;      /* look for the same line*/
             do  
          { 
           j=0; 
           matchflag=1;
              do 
           { 
            comparebit=(check[j]>>i)&1; /* get the [j][i] bit of the array*/
               if (check_out[j]!=comparebit) 
            {
             j=5;
             matchflag=0;
            }                /*not coincident,jump out at once*/
                     else 
                         j++;
           } 
                 while (j<5);
               
           if (matchflag==1) 
           {
           matchbit=i;
           i=15;
           }               /*if found,jump out at once*/
              else 
                 i++;
           }
              while (i<15);
            
           if (matchbit<=14)
              {
                code_bit[matchbit]=code_bit[matchbit]^1;    /*correct the error 
      bit*/
              }
           }
           code = 0;
           for(i=0;i<10;i++)
           {
               code |= (code_bit[i]<<i);
           }
           *code_out++ = code;
          }
      }