/* I came up with the following C routine to add 1 to an integer, in case your
   instruction set lacks that particular capability. I think it might have some
   hack value. By Brian */

int
inc (int x)
{
  int m = 1;
  while (m)
    {
      x ^= m;
      m = (m & ~x) << 1;
    }
  return x;
}

/* You can likewise subtract 1 from an integer through some simple 2s
   compliment manipulation, as follows:

   int dec(int x) {
     return inc(~inc(inc(~x)));
   }