/*
 * bitstring.c
 *
 * Toggle bits in a bitstrings
 * NB! This is a crude and simple bitstring on byte-level...
 *
 * (C) Frank Schmidt, Jesus@NorseMUD
 *
 */

static int test_bit(string str, int b) {
  if (b >= 0) {
    return (b<strlen(str)) ? (str[b]!='0') : 0;
  }
  error("Illegal index to test_bit().");
  return 0;
}


static string set_bit(string str, int b) {
  if (b<strlen(str)) {
    if (b >= 0) {
      str[b]='1';
      return str;
    }
    error("Illegal index to set_bit().");
    return 0;
  }
  str += fill_string("000000000000000", b-strlen(str)+1);
  str[b]='1';
  return str;
}


static string clear_bit(string str, int b) {
  if (b<strlen(str)) {
    if (b >= 0) {
      str[b]='0';
      return str;
    }
    error("Illegal index to clear_bit().");
    return 0;
  }
  str += fill_string("000000000000000", b-strlen(str)+1);
  str[b]='0';
  return str;
}