/* Reed-Solomon encoder

 * Copyright 2002, Phil Karn, KA9Q

 * May be used under the terms of the GNU General Public License (GPL)

 */

#include <string.h>

#ifdef FIXED

#include "fixed.h"

#elif defined(BIGSYM)

#include "int.h"

#else

#include "char.h"

#endif

void ENCODE_RS(

#ifndef FIXED

void *p,

#endif

DTYPE *data, DTYPE *bb){

#ifndef FIXED

  struct rs *rs = (struct rs *)p;

#endif

  unsigned int i, j;

  DTYPE feedback;

  memset(bb,0,NROOTS*sizeof(DTYPE));

  for(i=0;i<NN-NROOTS;i++){

    feedback = INDEX_OF[data[i] ^ bb[0]];

    if(feedback != A0){      /* feedback term is non-zero */

#ifdef UNNORMALIZED

      /* This line is unnecessary when GENPOLY[NROOTS] is unity, as it must

       * always be for the polynomials constructed by init_rs()

       */

      feedback = MODNN(NN - GENPOLY[NROOTS] + feedback);

#endif

      for(j=1;j<NROOTS;j++)

        bb[j] ^= ALPHA_TO[MODNN(feedback + GENPOLY[NROOTS-j])];

    }

    /* Shift */

    memmove(&bb[0],&bb[1],sizeof(DTYPE)*(NROOTS-1));

    if(feedback != A0)

      bb[NROOTS-1] = ALPHA_TO[MODNN(feedback + GENPOLY[0])];

    else

      bb[NROOTS-1] = 0;

  }

}