viterbi_cc.c

这个文件包括wimax中所有的编解码源代码

/*****************************************************************************/
/*   FIle Name : viterbi_cc.c                                                */
/*   Description : WiMax FEC Viterbi decoder                                 */
/*                 64x64 search                                              */
/*                 g0=171o g1=133o                                           */
/*   author : miffie                                                         */
/*   Date   : Nov/03/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                        */
/*****************************************************************************/
struct binaryset viterbi_cc (struct binaryset datain ) {
int 	ii , jj ;
short 	tmp0, tmp1, tmp2 ;
struct 	binaryset bset ;
char    *p, *q ;
char    *top ;
short	brmetric[4] ;
short 	metric0[64], metric1[64] ;
short	minimum_metric ;
short	won_metric ;
char	conv[64][4] ;
char	won[64] ;
int     size_q ;
long long   sdata0[64],sdata1[64] ;
short	MAX_METRIC = 0x7f ;

  //Main 
    PRINTF("viterbi_cc size=%d\n", datain.size ) ;
    if ((top = (char *)malloc((datain.size/2)*sizeof(char)) ) == NULL) {
        PRINTF( " malloc failed in viterbi_cc.c\n") ;
    } //fail
    else { //allocated
      //initialize
      for(ii=0;ii<64;ii++) { //init
        metric0[ii] = MAX_METRIC ;
        conv[ii][0] = conv_enc(ii+0) ;
        conv[ii][1] = conv_enc(ii+0x40) ;
      } //init
      metric0[0] = 0 ; //assumed the shiftregister reset to 0
      p = datain.data ;
      q = top ;
      size_q = 0 ;
      for(ii=0;ii<datain.size;ii=ii+2) { //each cycle
        //branch metric
        tmp1 = *p++ ;
        tmp2 = *p++ ;
        brmetric[0] = tmp1 + tmp2 ;
        brmetric[1] = (0xf-tmp1) + tmp2 ;
        brmetric[2] = tmp1 + (0xf-tmp2) ;
        brmetric[3] = (0xf-tmp1) + (0xf-tmp2) ;
       
        //metric
        minimum_metric = MAX_METRIC ;
        for(jj=0;jj<64;jj++) { //each metric1
           tmp0 = (jj>>1) + 0 ;
           tmp1 = (jj>>1) + 0x20 ;
           //printf("%d %d metric[%d]=%d metric[%d]=%d\n", ii, jj, tmp0, metric0[tmp0], tmp1, metric0[tmp1] ) ;
           //printf("%d %d brmetric[%d]=%d brmetric[%d]=%d\n",ii, jj, conv[jj][0], brmetric[ conv[jj][0] ] , conv[jj][1], brmetric[ conv[jj][1] ] ) ;
           tmp0 = metric0[tmp0] + brmetric[ conv[jj][0] ]  ;
           tmp1 = metric0[tmp1] + brmetric[ conv[jj][1] ]  ;
           //printf("%d %d tmp0=%d tmp1=%d\n",ii, jj, tmp0, tmp1 ) ;
           won[jj] = 0 ;
           if (tmp0>tmp1) {
              tmp0 = tmp1 ; //tmp0 =min(tmp0,tmp1) ;
              won[jj] = 1 ;
           }
           metric1[jj] = tmp0 ;
           //limitter
           if (metric1[jj] > MAX_METRIC ) metric1[jj] = MAX_METRIC ;
           //printf("%d metric[%d]=%d\n", ii, jj,  metric1[jj] ) ;
           
           if (metric1[jj] < minimum_metric) {
               minimum_metric = metric1[jj] ;
               won_metric = jj ;
           }
           //serial data process
           if (won[jj]) {
               sdata1[ jj ] = (sdata0[ (jj>>1) + 0x20 ]<<1) + 0x1 ;
           } else {
               sdata1[ jj ] = (sdata0[ (jj>>1) + 0x0 ]<<1) + 0x0 ;
           }
           
        } //each metric1

        for(jj=0;jj<64;jj++) { //each metric1
          //Normalization
          metric1[jj] -= minimum_metric ; //force the won_metric to zero
          //copy metric1 to metric0 for the next cycle operation
          metric0[jj] = metric1[jj] ;
          //copy metric1 to metric0 for the next cycle operation
          sdata0[jj] = sdata1[jj] ;
        } //each metric1
      
        if (ii>136)  {//output
           *q++ = (sdata1[won_metric]>>63) & 0x1 ;
           size_q++ ;
        } //output
        
        
      } //each cycle

     bset.format = 0 ;
     bset.size = size_q ;
     bset.data = top ;
    }//allocated
    free ( datain.data ) ;
    return ( bset ) ;
} //viterbi_cc