ctc_decoder.c

这个文件包括wimax中所有的编解码源代码

/*****************************************************************************/
/*   FIle Name : ctc_decoder.c                                               */
/*   Description : WiMax OFDM FEC CTC Decoder                                */
/*   author : miffie                                                         */
/*   Date   : Nov/15/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                        */
/*****************************************************************************/
struct binaryset ctc_decoder (struct binaryset datain,
                               char fec_code_type, char Nsub ) {
//input format must be 1  and each bit data is SOFT(0x0-0xf)

int 	ii , jj , NN, repeat ;
char 	tmp1 , tmp2 , shifter ;
char	*top ;
struct 	binaryset bset0, bset1 , bset2 ;
char    bdat[ 64 ] ;
char    edat[ 64 ] ;
char    fdat[ 64 ] ;
char  	parity, sum_parity, previous_sum ;
char    fail ;
char    rowtype, columntype ;
char    row, column , nx, ny;
static  UNKWN= 8 ;
//                               row column Ix  Iy  B  Q
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} ;
  //Main
    NN = ctc_parameters[fec_code_type-13][0] * Nsub ;
    if ((top = (char *)malloc(NN*4*sizeof(char)) ) == NULL) {
        PRINTF( " malloc failed in ctc_decoder.c\n") ;
    } //fail
    else { //allocated
     PRINTF( "ctc_decoder.c size=0x%x\n", datain.size ) ;
     bset0.format= 1 ;
     bset0.size= NN*4 ;
     bset0.data= top ;
     //bset0 MAP 
     //0 - 2*NN-1   A0,B0,....,An-1,Bn-1
     //2*NN -3*NN-1 Y10,Y11,....Y1n-1 (before Puncturing)
     //3*NN -4*NN-1 Y20,Y21,....Y2n-1 (before Puncturing)
     for(ii=0;ii<2*NN;ii++) {//for
        bset0.data[ii]  = datain.data[ii] ;
     }//for
     /////////////////////////////////////////////////////////
     //DePuncturing
     if (ctc_parameters[fec_code_type-13][2]==1) { //1:1/2
       for(ii=2*NN;ii<4*NN;ii++) { //for
         bset0.data[ii]  = datain.data[ii] ;
       }//for
     } else if (ctc_parameters[fec_code_type-13][2]==2) { //2:2/3
       for(ii=0;ii<(NN/2);ii++) { //for
         bset0.data[2*NN+2*ii]  = datain.data[2*NN+ii] ;
         bset0.data[2*NN+2*ii+1]  = UNKWN ;
         bset0.data[3*NN+2*ii]  = datain.data[2*NN+(NN/2)+ii] ;
         bset0.data[3*NN+2*ii+1]  = UNKWN ;
       }//for
     } else if (ctc_parameters[fec_code_type-13][2]==3) { //3:3/4
       for(ii=0;ii<(NN/3);ii++) { //for
         bset0.data[2*NN+3*ii]  = datain.data[2*NN+ii] ;
         bset0.data[2*NN+3*ii+1]  = UNKWN ;
         bset0.data[2*NN+3*ii+2]  = UNKWN ;
         bset0.data[3*NN+3*ii]  = datain.data[2*NN+(NN/3)+ii] ;
         bset0.data[3*NN+3*ii+1]  = UNKWN ;
         bset0.data[3*NN+3*ii+2]  = UNKWN ;
       }//for
     } //3:3/4

     //Loop
     print_binaryset( bset0 ) ;
     for (repeat=0; repeat<2; repeat++) {//repeat
       /////////////////////////////////////////////////////////
       //Natural order Decoder
       /////////////////////////////////////////////////////////
       bset1 = extract_binaryset( bset0, 0,  NN*3 ) ;
       bset1 = viterbi_ctc( bset1 ) ;
       //Copy back to SoftOutput to bset0
       for (jj=0;jj<NN*3;jj++) { //for
         bset0.data[jj] = bset1.data[jj] ;
       } //for
       print_binaryset( bset0 ) ;

       /////////////////////////////////////////////////////////
       //Interleaved Decoder
       /////////////////////////////////////////////////////////
       bset1 = extract_binaryset( bset0, 0,  NN*2 ) ;
       bset1 = ctc_interleaver( bset1 ,  ctc_parameters[fec_code_type-13][1]) ;
       bset2 = extract_binaryset( bset0, NN*3,  NN ) ;
       bset1 = cat_binaryset( bset1, bset2 ) ;
       bset1 = viterbi_ctc( bset1 ) ;
       bset2 = extract_binaryset( bset1, 0,  NN*2 ) ;
       bset2 = ctc_deinterleaver( bset2 ,  ctc_parameters[fec_code_type-13][1]) ;
       //Copy back to SoftOutput to bset0
       for (jj=0;jj<NN*2;jj++) { //for
         bset0.data[jj] = bset2.data[jj] ;
       } //for
       for (jj=0;jj<NN;jj++) { //for
         bset0.data[jj+3*NN] = bset1.data[jj+2*NN] ;
       } //for
       print_binaryset( bset0 ) ;
     } //repeat

     /////////////////////////////////////////////////////////
     //Soft to Hard Decision
     bset0.data = top ;
     bset0.size = NN*2 ;
     bset0.format = 0 ;
     for(jj=0;jj<bset0.size;jj++) { //each data 
             bset0.data[jj] = (bset0.data[jj]>=8) ? 1 : 0 ;
     } //each data
      /////////////////////////////////////////////////////////
    } //allocated
    free ( datain.data ) ;
    bset0 = binary2byte_MSB( bset0 ) ;
    return ( bset0 ) ;
} //ctc_decoder