/*****************************************************************************//*   FIle Name : viterbi_turbo2.c                                            *//*   Description : WiMax FEC Viterbi Decoder Pipe#2&#3 for Code Type4        *//*   author : miffie                                                         *//*   Date   : sep/26/05                                                      *//*   Copyright (c) 2005 miffie   All rights reserved.                        *//*****************************************************************************///One line correction in turbo decoder will be done through 3 pipeline stages//#1  check metrics calculation in normal order//    write into Soft memory (in first row iteration )//#2  Error estimation in reverse order//    read from Soft memory//    write into path memory//#3  trace back with SoftOutput//    read from both Soft memory & pathmemory//    write back to Soft memory//In this viterbi_turbo2, #2 &#3 are exercised.struct binaryset viterbi_turbo2 (char type, struct binaryset datain ,                      struct binaryset metric, char *parity ) {int 	ii , jj , kk ;char    nn , pp ;short 	tmp0, tmp1, tmp2 ;struct 	binaryset bset ;short	brmetric[4] ;short 	metric0[128], metric1[128] ;short	minimum_metric ;short	won_metric ;char	state[128][4] ;char	branch[128] ;char    pathmem[64][64] ; short	MAX_METRIC = 0x7f ;char    SISO_SHIFT = 3 ;char    BRANCH_OFFSET = 0 ;  //Main    //initialize     PRINTF( "viterbi_turbo2.c size=%x %d m0=%d\n", datain.size, *parity , metric.data[0]) ;    nn =  (type==1) ? 0xf :          (type==2) ? 0x1f : 0x3f ;    pp =  (type==1) ? 0x5 :   //lfsr+parity length          (type==2) ? 0x6 : 0x7 ;    for(ii=0;ii<=nn;ii++) { //init      state[ii][0] = lfsr( type, 0 , ii ) & nn ;                      //+ ((ii&0x1) ? 1 : 0) ; //parity      state[ii][1] = lfsr( type, 1 , ii ) & nn ;                     //+ ((ii&0x1) ? 0 : 1) ; //parity    } //init    //for(ii=0;ii<=nn;ii++) printf("state(%x %x) %x\n", ii, 0, state[ii][0] ) ;    //for(ii=0;ii<=nn;ii++) printf("state(%x %x) %x\n", ii, 1, state[ii][1] ) ;////////////////////////////////////////////////////////////////////#2  Error estimation in reverse order//////////////////////////////////////////////////////////////////  if ((type<4)&((*parity>0)|(metric.data[0]>0))) { //error    //initialize metrics    for(ii=0;ii<=nn;ii++)        metric0[ii] = metric.data[ii] ;    for(ii=datain.size-2;ii>=0;ii--) { //each cycle in REVERSE order      //branch metric      //state0-31      brmetric[0] = (datain.data[ii]>=8)  ? 0xf-datain.data[ii] : datain.data[ii]  ;      brmetric[0] += BRANCH_OFFSET;      brmetric[1] = 0xf - brmetric[0] ;      minimum_metric = MAX_METRIC ;      //metric      for(jj=0;jj<=nn;jj++) { //each state         tmp0 = state[jj][0] ;         tmp1 = state[jj][1] ;         //printf("%d %x metric[%x]=%x metric[%x]=%x\n", ii, jj, tmp0, metric0[tmp0], tmp1, metric0[tmp1] ) ;         //printf("%d %x brmetric[0]=%x brmetric[1]=%x\n",ii, jj,  brmetric[0] , brmetric[1] ) ;         tmp0 = metric0[tmp0] + brmetric[0]  ;         tmp0 = (tmp0>MAX_METRIC) ? MAX_METRIC : tmp0 ;         tmp1 = metric0[tmp1] + brmetric[1]  ;         tmp1 = (tmp1>MAX_METRIC) ? MAX_METRIC : tmp1 ;         //printf("%d %d tmp0=%d tmp1=%d\n",ii, jj, tmp0, tmp1 ) ;         pathmem[ii][jj] = tmp0-tmp1 ;         if (tmp0>=tmp1) {            tmp0 = tmp1 ; //tmp0 =min(tmp0,tmp1) ;         }         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 ;         }      } //each state      //printf("%d won_metric = %x\n", ii, won_metric ) ;      //printf("%d pathmem1(%x) = %x\n", ii, won_metric, pathmem1[won_metric]) ;      for(jj=0;jj<=nn;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        //pathmem0[jj] = pathmem1[jj] ;      } //each metric1    } //each cycle    ////////////////////////////////////////////////////////////////////#3  trace back with SoftOutput//////////////////////////////////////////////////////////////////      //output       *parity = 0 ;      won_metric=0 ; //because check should be zero at the end of calcuration      for(jj=0;jj<datain.size-1;jj++)  { //output        tmp1 = pathmem[jj][won_metric] ;        printf("datain.data(%d)=%x path(%x)=%x ", jj,  datain.data[jj], won_metric, tmp1) ;        //SISO Softin Softout        datain.data[jj] = ((tmp1<=0)&(datain.data[jj]==0))  ? 0 :                          ((tmp1<=0)&(datain.data[jj]<8))  ? datain.data[jj]+(tmp1>>SISO_SHIFT) :                          ((tmp1<=0)&(datain.data[jj]==0xf))  ? 0xf :                           (tmp1<=0) ? datain.data[jj]-(tmp1>>SISO_SHIFT) :                           ((tmp1>0)&(datain.data[jj]<8))  ? 8+(tmp1>>SISO_SHIFT) :                       /* (tmp1==1)  ? */ 7-(tmp1>>SISO_SHIFT) ;        datain.data[jj] = (datain.data[jj]<0 ) ? 0 :                          (datain.data[jj]>0xf) ? 0xf : datain.data[jj] ;       printf("=>%x\n", datain.data[jj]) ;       *parity ^= (datain.data[jj]>=8) ? 1 : 0 ;       if ( tmp1 > 0  ) won_metric = state[won_metric][1]  ;        else  won_metric = state[won_metric][0] ;      } //output      //*parity ^= (datain.data[datain.size-1]>=8) ? 1 : 0 ;      //if( *parity > 0) { //parity error      //  for(jj=0;jj<datain.size;jj++)  { //output      //    datain.data[jj] = (datain.data[jj]>=8)  ? datain.data[jj] -1  :      //                       datain.data[jj] +1 ;      //  } //output      //}//parity error  } //error   else if ((*parity==0)&(metric.data[0]==0)) { //no error      for(jj=0;jj<datain.size;jj++)  { //output        datain.data[jj] = (datain.data[jj]==0 ) ? 0 :                          (datain.data[jj]==0xf) ? 0xf :                          (datain.data[jj]>=8)  ? datain.data[jj] +1  : datain.data[jj] -1 ;      } //output  } //no errors  else if (*parity>0) { //error        for(jj=0;jj<datain.size;jj++)  { //output          datain.data[jj] = (datain.data[jj]>=8)  ? datain.data[jj] -1  :                             datain.data[jj] +1 ;        } //output  } //error  return ( datain ) ;} //viterbi_turbo2