sclass GlobalID {
  // We need 76 bits for 26^16 IDs
  long a;
  int b;
  
  *() {}
  *(S id) {
    assertGlobalID(id);
    BigInt value = bigint(0);
    for (int i = 0; i < l(id); i++)
      value = plus(mul(value, 26), charDiff(id.charAt(i), 'a'));
      
    ifdef GlobalID_debug
    print("value in constructor: " + value);
    endifdef
    a = value.longValue();
    value = value.shiftRight(64);
    b = value.intValue();
  }
  
  toString {
    BigInt value = bigint(b);
    value = value.shiftLeft(32);
    value = plus(value, (a >> 32) & 0xFFFFFFFFL);
    value = value.shiftLeft(32);
    value = plus(value, a & 0xFFFFFFFFL);
    
    ifdef GlobalID_debug
    print("value in toString: " + value);
    endifdef
    
    char[] buf = new char[16];
    for (int i = 16-1; i >= 0; i--) {
      buf[i] = charPlus('a', mod(value, 26).intValue());
      value = div(value, 26);
    }
    ret str(buf);
  }
}