990923-1.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

#define mask  0xffff0000L
#define value 0xabcd0000L

long
foo (long x)
{
  if ((x & mask) == value)
    return x & 0xffffL;
  return 1;
}

int 
main (void)
{
  if (foo (value) != 0 || foo (0) != 1)
    abort ();
  
  exit (0);
}