/* clkhandler.c - clkhandler */

/* avr specific */

#include <xinu.h>

#include <avr/io.h>
#include <avr/interrupt.h>

volatile unsigned int avr_ticks=0;

/*-----------------------------------------------------------------------
 * clkhandler - high level clock interrupt handler
 *-----------------------------------------------------------------------
 */

/* void clkhandler() */

ISR(TIMER0_COMPA_vect)
{

	/* Every ms */

	/* Increment 1000ms counter */

	count1000++;

	/* After 1 sec, increment clktime */

	if(count1000 >= 1000) {	/* previous was: if(count1000 >= 1000) */
		clktime++;
		count1000 = 0;
	}

	if(!isempty(sleepq)) {
		/* sleepq nonempty, decrement the key of */
		/* topmost process on sleepq             */

		if((--queuetab[firstid(sleepq)].qkey) == 0) {

			wakeup();
		}
	}

	/* Decrement the preemption counter */
	/* Reschedule if necessary          */
	if((--preempt) == 0) {
		preempt = QUANTUM;
		resched();
	}
}