fecdec.c

这个文件包括wimax中所有的编解码源代码

/*****************************************************************************/
/*   FIle Name : fecdec.c                                                    */
/*   Description : WiFi OFDM FEC Decoder                                     */
/*   author : miffie                                                         */
/*   Date   : Nov/23/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                        */
/*****************************************************************************/

struct binaryset fecdec(struct binaryset datain , 
                              char fec_code_type,
                              short *randomizer_seed ) {
  register int ii , jj ;
  char num_erasure ;
  char RR ;
  char unfixable ;
  short  KK  , num_data , size  ;
  struct  binaryset bset0, bset1, bset2 , bset3;
  unsigned char     data[256] ;
  char    Nsub = 16 ;
  short   row, column, tmp1 ;
  //   rs_cc           RS_K  RS_T  RATE Ncpc
  char rs_cc[7][4] = {{   12,    0,   0,   1 },
                      {   24,    4,   1,   2 },
                      {   36,    2,   3,   2 },
                      {   48,    8,   1,   4 },
                      {   72,    4,   3,   4 },
                      {   96,    6,   2,   6 },
                      {  108,    6,   3,   6 } } ;
  short btc_block[] =  {  24,  24,  48,  48,  72,  72 } ;
  short ctc_block[] =  {  24,  24,  24,  48,  48,  72,  72 } ;




  PRINTF("fecdec    fec_code_type=%d size=%d\n", fec_code_type , datain.size ) ;
    //////////////////////////////////////////////////////////////////////////////
    // Inner Code 
    //////////////////////////////////////////////////////////////////////////////
    if  (fec_code_type<=6) {
      //depuncturing
      bset0 = depuncturing(datain , rs_cc[fec_code_type][2] ) ; //rate 2:3/4
      bset1 = pad_binaryset(138) ;
      bset0 = cat_binaryset(bset0 , bset1) ;
      print_binaryset( bset0 ) ;
      bset0 = viterbi_cc( bset0 ) ;    
      print_binaryset(bset0) ;
      bset0 = binary2byte_MSB(bset0) ;
      print_binaryset(bset0) ;
    }
    else if (fec_code_type<=12) { //BTC
      ii= 0 ;
      bset2.size= 0 ;
      bset2.format= 1 ; //Byte
      while (ii < datain.size ) { //while
            printf("btc_block=%d\n",  (btc_block[fec_code_type-7]*Nsub) ) ;
            bset1 = extract_binaryset( datain, ii, (btc_block[fec_code_type-7]*Nsub) ) ; 
            bset1 = turbo_decoder( bset1, fec_code_type, Nsub ) ;
            bset2 = cat_binaryset( bset2, bset1 ) ;
            ii += (btc_block[fec_code_type-7]*Nsub) ;
      } //while
    } //BTC
    else if (fec_code_type<=19) { //CTC
      ii= 0 ;
      bset2.size= 0 ;
      bset2.format= 1 ; //Byte
      while (ii < datain.size ) { //while
            printf("ctc_block=%d\n",  (ctc_block[fec_code_type-13]*Nsub) ) ;
            bset1 = extract_binaryset( datain, ii, (ctc_block[fec_code_type-13]*Nsub) ) ; 
            bset1 = ctc_decoder( bset1, fec_code_type, Nsub ) ;
            bset2 = cat_binaryset( bset2, bset1 ) ;
            printf("cat_binaryset done\n") ;
            ii += (ctc_block[fec_code_type-13]*Nsub) ;
      } //while
    } //CTC

    //////////////////////////////////////////////////////////////////////////////
    // Outer Code ( Reed-Solomon)
    //////////////////////////////////////////////////////////////////////////////
    if (fec_code_type==0) { //NO RS
      bset2 = copy_binaryset( bset0 ) ;
    } //NO RS
    else if (fec_code_type<=6) { //RS
      unfixable=0 ;
      bset2.size= 0 ;
      bset2.format= 0 ; //Binary
      size=bset0.size ;
        ii= 0 ;
        while (ii < bset0.size ) { //while
          if ( (bset0.size-ii) >= rs_cc[fec_code_type][0] + rs_cc[fec_code_type][1]*2 ) { //fixed size
            bset1 = extract_binaryset( bset0, ii, 
                    rs_cc[fec_code_type][0] + rs_cc[fec_code_type][1]*2 ) ;
            bset1 =  decode_rs(bset1, rs_cc[fec_code_type][1]*2) ;
            if (bset1.size > rs_cc[fec_code_type][0] ) { //unfixable 
              unfixable = 1 ;
              bset1.size -= rs_cc[fec_code_type][1]*2 ;
            }  //unfixable
            bset2 = cat_binaryset( bset2, bset1 ) ;
          } 
          else if ((bset0.size-ii) >= 6 + rs_cc[fec_code_type][1]*2 ) {//lastword
            bset1 = extract_binaryset( bset0, ii, 
                    bset0.size-ii ) ;
            bset1 =  decode_rs(bset1, rs_cc[fec_code_type][1]*2  ) ;
            if (bset1.size == bset0.size-ii ) { //unfixable 
              unfixable = 1 ;
              bset1.size -= rs_cc[fec_code_type][1]*2  ;
            }  //unfixable
            bset2 = cat_binaryset( bset2, bset1 ) ;
          } //lastword
          ii += rs_cc[fec_code_type][0] + rs_cc[fec_code_type][1]*2 ;
        } //while
      print_binaryset(bset2) ;
    } //RS
  
    //////////////////////////////////////////////////////////////////////////////
    // randomization
    //////////////////////////////////////////////////////////////////////////////
    if (fec_code_type<=6) {
      bset2 = extract_binaryset( bset2, 0 , bset2.size-1 ) ; //remove tail byte
    }
    bset2 = byte2binary_MSB( bset2 ) ;
    bset2 = randomizer( bset2 , randomizer_seed ) ; //only accept format= 0 (binary);
    bset2 = binary2byte_MSB( bset2 ) ;
 
    print_binaryset(bset2) ;
    return( bset2 ) ;
} //fecdec