/* ****************SPIN.C********
  Jonathan W. Valvano   Feb 26, 1997
  Spinlock semaphores */
void Wait(int *semaphore){
     asm(" sei");  /* Test and set is atomic */
	 PORTC|=0x10;
     while((*semaphore)<=0){      /* disabled */
         asm(" cli\n"             /* disabled */
		     " nop\n"             /* enabled  */
             " sei");}            /* enabled  */
     (*semaphore)--;              /* disabled */
	 PORTC&=0xEF;
     asm(" cli");                 /* disabled */
}                                 /* enabled  */
void Signal(int *semaphore){
     asm(" sei");  /* increment is atomic */
	 PORTC|=0x20;
     (*semaphore)++;
	 PORTC&=0xDF;
     asm(" cli");
}