ctc_encoder.c

这个文件包括wimax中所有的编解码源代码

/*****************************************************************************/
/*   FIle Name : ctc_encoder.c                                               */
/*   Description : WiMax OFDM FEC Convolutional Turbo Codes                  */
/*   author : miffie                                                         */
/*   Date   : Nov/21/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                        */
/*****************************************************************************/

char  constituent_encoder ( char aa, char bb, char *state ) {
char  tmp0, tmp1  ;

   tmp0 = (*state &0x1) ^ ((*state>>2)&0x1) ^ aa ^ bb ;
   tmp0 += (((*state &0x1) ^ bb) & 0x1) << 1 ;
   tmp0 += ((((*state>>1)&0x1) ^ bb) & 0x1) << 2 ;
   tmp1 = ((*state>>2)&0x1) ^  ((*state>>1)&0x1)  ^ (tmp0 &0x1) ;
   *state = tmp0&0x7 ;
   return ( tmp1 ) ;
} //constituent_encoder

struct binaryset ctc_interleaver (struct binaryset datain,
                               char P0 ) { 
short  ii,jj ;
char   tmp1 ;
char   data[864] ; //QAM64:27*16*2 
short  P1 = 3*datain.size/8 ;
  //Step 1: Swich alternate Couples
  for (jj=0;jj<datain.size;jj+=4) { //for
    tmp1 = datain.data[jj+2] ;
    datain.data[jj+2] =  datain.data[jj+3] ;
    datain.data[jj+3] = tmp1 ;
  }//for

  //Step 2: Pi(j)
  for (jj=1;jj<=(datain.size/2);jj++) { //for
    ii = ((jj%4)==2) ?  (P0*jj+1+(datain.size/8))%(datain.size/2) :
         ((jj%4)==3) ?  (P0*jj+1+(datain.size/4))%(datain.size/2) :
                        (P0*jj+1)%(datain.size/2) ;
    if (ii==0) ii=(datain.size/2) ;
    data[ii*2-2] = datain.data[jj*2-2] ;
    data[ii*2-1] = datain.data[jj*2-1] ;
    //printf("interleaver (%d=>%d) 0b%x%x\n", jj, ii, data[ii*2-2] , data[ii*2-1]  ) ;
  } //for
  //copy back to datain
  for (ii=0;ii<datain.size;ii++) { //for
        datain.data[ii] = data[ii] ;
  } //for
  return( datain ) ;
} //ctc_interleaver

struct binaryset ctc_deinterleaver (struct binaryset datain,
                               char P0 ) { 
short  ii,jj ;
char   tmp1 ;
char   data[864] ; //QAM64:27*16*2 
short  P1 = 3*datain.size/8 ;

  //Step 2: Pi(j)
  for (jj=1;jj<=(datain.size/2);jj++) { //for
        ii = ((jj%4)==2) ?  (P0*jj+1+(datain.size/8))%(datain.size/2) :
             ((jj%4)==3) ?  (P0*jj+1+(datain.size/4))%(datain.size/2) :
                            (P0*jj+1)%(datain.size/2) ;
        if (ii==0) ii=(datain.size/2) ;
        data[jj*2-2] = datain.data[ii*2-2] ;
        data[jj*2-1] = datain.data[ii*2-1] ;
        //printf("deinterleaver (%d=>%d) 0b%x%x\n", jj, ii, data[jj*2-2] , data[jj*2-1]  ) ;
  } //for

  //Step 1: Swich alternate Couples
  for (jj=0;jj<datain.size;jj+=4) { //for
    tmp1 = data[jj+2] ;
    data[jj+2] =  data[jj+3] ;
    data[jj+3] = tmp1 ;
  }//for

  //copy back to datain
  for (ii=0;ii<datain.size;ii++) { //for
        datain.data[ii] = data[ii] ;
  } //for
  return( datain ) ;
} //ctc_deinterleaver


struct binaryset ctc_encoder (struct binaryset datain,
                               char fec_code_type, char Nsub ) {
//input format must be 1 
int 	ii , jj , kk , NN ;
char 	tmp1 , tmp2 , shifter, parity ;
char	*qq;
struct  binaryset bset0 , bset1 , bset2 ;
char    state ;

//                            N/Nsub P0 Puncture
char  ctc_parameters[7][3] = { {  6,  7,  1 },
                               {  8, 11,  2 },
                               {  9, 17,  3 },
                               { 12, 11,  1 },
                               { 18, 13,  3 },
                               { 24, 17,  2 },
                               { 27, 17,  3 } } ;
char Npsub[7] = { 24, 24, 24, 48, 48, 72, 72} ;
//This table is worked well with the current cmodel.
//Nov/22/05 Miffie
char sc[7][8] = { {0, 1, 2, 3, 4, 5, 6, 7},
                  {0, 4, 5, 1, 2, 6, 7, 3} ,
                  {0, 2, 6, 4, 5, 7, 3, 1} ,
                  {0, 5, 7, 2, 6, 3, 1, 4} ,
                  {0, 6, 3, 5, 7, 1, 4, 2} ,
                  {0, 7, 1, 6, 3, 4, 2, 5} ,
                  {0, 3, 4, 7, 1, 2, 5, 6} } ;

/***********************************************************
//This s a Table 221-Circulation state lookup table,
//But somehow this does not match with the current cmodel.
char sc[7][8] = { {0, 1, 2, 3, 4, 5, 6, 7},
                  {0, 6, 4, 2, 7, 1, 3, 5},
                  {0, 3, 7, 4, 5, 6, 2, 1},
                  {0, 5, 3, 6, 2, 7, 1, 4},
                  {0, 4, 1, 5, 6, 2, 7, 3},
                  {0, 2, 5, 7, 1, 3, 4, 6},
                  {0, 7, 6, 1, 3, 4, 5, 2} } ;
***********************************************************/
  //Main 
    NN = ctc_parameters[fec_code_type-13][0] * Nsub ;
    
    PRINTF( "ctc_encoder.c size=%x\n", datain.size ) ;
    datain  = byte2binary_MSB( datain ) ;
    bset0 = copy_binaryset( datain ) ;
    bset1 = copy_binaryset( datain ) ;
    bset1 = ctc_interleaver( bset1 ,  ctc_parameters[fec_code_type-13][1]) ;
    print_binaryset( bset1 ) ;

    //C1 Constituent Encoder
    state = 0 ;
    for(ii=0;ii<bset0.size;ii+=2) { //C1
          tmp1 = constituent_encoder ( 
                              bset0.data[ii], bset0.data[ii+1], &state ) ;
    } //C1
    printf("C1 last state=%x\n", state ) ;
    state = sc[NN%7][state] ;
    for(ii=0;ii<bset0.size;ii+=2) { //C1
          bset0.data[ii/2]  = constituent_encoder ( 
                              bset0.data[ii], bset0.data[ii+1], &state ) ;
    } //C1
    printf("C1 last state=%x\n", state ) ;
    bset0.size = bset0.size/2 ;

    //C2 Constituent Encoder
    state = 0 ;
    for(ii=0;ii<bset1.size;ii+=2) { //C2
          tmp1 = constituent_encoder ( 
                              bset1.data[ii], bset1.data[ii+1], &state ) ;
    } //C2
    printf("C2 last state=%x\n", state ) ;
    state = sc[NN%7][state] ;
    for(ii=0;ii<bset1.size;ii+=2) { //C2
          bset1.data[ii/2]  = constituent_encoder ( 
                              bset1.data[ii], bset1.data[ii+1], &state ) ;
    } //C2
    printf("C2 last state=%x\n", state ) ;
    bset1.size = bset1.size/2 ;

    //Puncturing
    if (ctc_parameters[fec_code_type-13][2]==2) { //2:2/3
      for(ii=0;ii<bset1.size;ii+=2) { //2:2/3
          bset0.data[ii/2] = bset0.data[ii] ;
          bset1.data[ii/2] = bset1.data[ii] ;
      } //2:2/3
      bset0.size = bset0.size/2 ;
      bset1.size = bset1.size/2 ;
    } //2:2/3
    else if (ctc_parameters[fec_code_type-13][2]==3) { //3:3/4
      for(ii=0;ii<bset1.size;ii+=3) { //3:3/4
          bset0.data[ii/3] = bset0.data[ii] ;
          bset1.data[ii/3] = bset1.data[ii] ;
      } //3:3/4
      bset0.size = bset0.size/3 ;
      bset1.size = bset1.size/3 ;
    } //3:3/4

    //Concatinate the parities
    bset0 = cat_binaryset(datain, bset0) ;
    bset0 = cat_binaryset(bset0, bset1) ;
    //free ( datain.data ) ;
    return ( bset0 ) ;
} //ctc_encoder