/* ****************SPIN.C********
   Spinlock semaphores for the MC68HC11EVB

   This example accompanies the book
     "Embedded Microcomputer Systems: Real Time Interfacing", Brooks-Cole, copyright (c) 2000,
      Jonathan W. Valvano 7/6/99

   Interface between the TExaS simulator running a MC68HC11 EVB
      with ICC11 freeware compiler 
   TExaS Copyright 1999 by Jonathan W. Valvano 
   for more information about ICC11 
      see http://www.imagecraft.com
   You may use this file without restrictions
*/
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");  /* make increment is atomic */
    PORTC|=0x20;
    (*semaphore)++;
    PORTC&=0xDF;
    asm(" cli");
}