/* Reed-Solomon encoder
 * Copyright 2002, Phil Karn, KA9Q
 * May be used under the terms of the GNU Lesser General Public License (LGPL)
 */
#include <string.h>

#ifdef FIXED
#include "fixed.h"
#elif defined(BIGSYM)
#include "int.h"
#else
#include "char.h"
#endif

void ENCODE_RS(
#ifdef FIXED
  data_t *data, data_t *bb, int pad)
{
#else
  void *p, data_t *data, data_t *bb)
{
  struct rs *rs = (struct rs *)p;
#endif
  int i, j;
  data_t feedback;

#ifdef FIXED
  /* Check pad parameter for validity */
  if (pad < 0 || pad >= NN) {
    return;
  }
#endif

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

  for (i = 0; i < NN - NROOTS - PAD; 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(data_t) * (NROOTS - 1));
    if (feedback != A0) {
      bb[NROOTS - 1] = ALPHA_TO[MODNN(feedback + GENPOLY[0])];
    }
    else {
      bb[NROOTS - 1] = 0;
    }
  }
}