1  int
       2  f (unsigned bitcount, int mant)
       3  {
       4    int mask = -1 << bitcount;
       5    {
       6      if (! (mant & -mask))
       7        goto ab;
       8      if (mant & ~mask)
       9        goto auf;
      10    }
      11  ab:
      12    return 0;
      13  auf:
      14    return 1;
      15  }
      16  
      17  main ()
      18  {
      19    if (f (0, -1))
      20      abort ();
      21    exit (0);
      22  }