convolution_encoder.c

这个文件包括wimax中所有的编解码源代码

/*****************************************************************************/
/*   FIle Name : convolution_encoder.c                                       */
/*   Description : WiMax OFDM FEC convolution_encoder for Encoder            */
/*                 g0=171o g1=133o                                           */
/*                 Rate 0:1/2 1:2/3 2:3/4 4:5/6                              */
/*   author : miffie                                                         */
/*   Date   : nov/01/05                                                      */
/*   Copyright (c) 2005 miffie   All rights reserved.                        */
/*****************************************************************************/
char 	conv_enc ( char shifter ) {
//output[0] g0
//      [1] g1
char    tmp1, tmp2 ;
        //g1=171o
        tmp1 = (shifter &0x1) ;
        tmp1 ^= ((shifter>>1) &0x1) ;
        tmp1 ^= ((shifter>>2) &0x1) ;
        tmp1 ^= ((shifter>>3) &0x1) ;
        tmp1 ^= ((shifter>>6) &0x1) ;
        //g0=133o
        tmp2 = (shifter &0x1) ;
        tmp2 ^= ((shifter>>2) &0x1) ;
        tmp2 ^= ((shifter>>3) &0x1) ;
        tmp2 ^= ((shifter>>5) &0x1) ;
        tmp2 ^= ((shifter>>6) &0x1) ;

        tmp1 = tmp1 + ((tmp2&0x1)<<1) ;

        //printf("shifter=%x tmp1=%x\n", shifter, tmp1 ) ;
        return (tmp1) ;
} //conv_enc

struct binaryset convolution_encoder (struct binaryset datain, char rate) {
int 	ii ;
int 	size_p ; //size for punctured
char 	shifter ;
char 	tmp1, tmp2 ;
char	*p , *q;
struct binaryset bset0 ;

  //Main 
    if ((q = (char *)malloc(2*datain.size*sizeof(char)) ) == NULL) {
        PRINTF( " malloc failed in convolution_encoder.c\n") ;
    } //fail
    else { //allocated
       PRINTF( "convolution_encoder.c size=0x%x coding_rate=%d\n", datain.size, rate) ;
       p = datain.data ;
       bset0.format = 0 ; //a bit
       bset0.size = 2*datain.size ; //
       bset0.data = q ; //
       shifter =0 ;

       /////////////////////////////////////////
       //convolution encode k=7 g0=171o g1=133o
       /////////////////////////////////////////
       for(ii=0;ii<datain.size;ii++) { //for
        shifter = (shifter<<1) + *p++ ;
        tmp1 = conv_enc (shifter) ;
        *q++ = tmp1 &0x1 ;   //g0
        *q++ = (tmp1>>1) &0x1 ; //g1
       } //for
       //print_binaryset( bset0 ) ;

       /////////////////////////////////////////////
       //puncturing   Rate 0:1/2 1:2/3 2:3/4 3:5/6
       /////////////////////////////////////////////
       p=bset0.data ;
       q=bset0.data ;
       size_p=0 ;
       switch ( rate ) {//switch
         case 1: { //2/3
                   for (ii=0;ii<bset0.size;ii++) { //for
                     if ((ii%4)!=2) { *q++ = *p ; size_p++ ; }
                     p++ ; //increment every ii
                   } //for
                   break ;
                 } //2/3
         case 2: { //3/4
                   for (ii=0;ii<bset0.size;ii++) { //for
                     if (((ii%6)!=2)&&((ii%6)!=5)) { *q++ = *p ; size_p++ ; }
                     //printf("%d/6 = %d  %x\n", ii,(ii%6), *p ) ;
                     p++ ; //increment every ii
                   } //for
                   break ;
                 } //3/4
         case 3: { //5/6
                   for (ii=0;ii<bset0.size;ii++) { //for
                     if (((ii%10)!=2)&&((ii%10)!=5)&&((ii%10)!=6)&&((ii%10)!=9)) 
                         { *q++ = *p ; size_p++ ; }
                     //printf("%d/6 = %d  %x\n", ii,(ii%6), *p ) ;
                     p++ ; //increment every ii
                   } //for
                   break ;
                 } //5/6
         default : { //1/2
                   size_p = bset0.size ;
                   break ;
                 } //1/2
       }//switch
       bset0.size = size_p ; //

    } //allocated
    free ( datain.data ) ;
    return ( bset0 ) ;
} //convolution_encoder