unsigned long
udivmodsi4(unsigned long num, unsigned long den, int modwanted)
{
  unsigned long bit = 1;
  unsigned long res = 0;

  while (den < num && bit && !(den & (1L<<31)))
    {
      den <<=1;
      bit <<=1;
    }
  while (bit)
    {
      if (num >= den)
	{
	  num -= den;
	  res |= bit;
	}
      bit >>=1;
      den >>=1;
    }
  if (modwanted) return num;
  return res;
}