void fp_montgomery_calc_normalization(fp_int *a, fp_int *b)
{
  int     x, bits;

  /* how many bits of last digit does b use */
  bits = fp_count_bits (b) % DIGIT_BIT;
  if (!bits) bits = DIGIT_BIT;

  /* compute A = B^(n-1) * 2^(bits-1) */
  if (b->used > 1) {
     fp_2expt (a, (b->used - 1) * DIGIT_BIT + bits - 1);
  } else {
     fp_set(a, 1);
     bits = 1;
  }

  /* now compute C = A * B mod b */
  for (x = bits - 1; x < (int)DIGIT_BIT; x++) {
    fp_mul_2 (a, a);
    if (fp_cmp_mag (a, b) != FP_LT) {
      s_fp_sub (a, b, a);
    }
  }
}
void fp_montgomery_calc_normalization(fp_int *a, fp_int *b)
{
  int     x, bits;

   
  bits = fp_count_bits (b) % DIGIT_BIT;
  if (!bits) bits = DIGIT_BIT;

   
  if (b->used > 1) {
     fp_2expt (a, (b->used - 1) * DIGIT_BIT + bits - 1);
  } else {
     fp_set(a, 1);
     bits = 1;
  }

   
  for (x = bits - 1; x < (int)DIGIT_BIT; x++) {
    fp_mul_2 (a, a);
    if (fp_cmp_mag (a, b) != FP_LT) {
      s_fp_sub (a, b, a);
    }
  }
}