/* some example asm code */

unsigned long tmp;

void set_cr4(unsigned long n) {

  /* we cannot move anything directly into 
     %cr4. This must be done via %eax. Therefore
     we save %eax by pushing it then pop
     it at the end.
  */

  STATWORD ps;

  disable(ps);

  tmp = n;
  asm("pushl %eax");
  asm("movl tmp, %eax");		/* mov (move) value at tmp into %eax register. 
					   "l" signifies long (see docs on gas assembler)	*/
  asm("movl %eax, %cr4");
  asm("popl %eax");

  restore(ps);

}

unsigned long read_cr3(void) {

  STATWORD ps;
  unsigned long local_tmp;

  disable(ps);

  asm("pushl %eax");
  asm("movl %cr3, %eax");
  asm("movl %eax, tmp");
  asm("popl %eax");

  local_tmp = tmp;

  restore(ps);

  return local_tmp;
}