#include <stdio.h>
#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include "task.h"

typedef struct Alarm Alarm;
struct Alarm
{
	Alarm *next;
	Rendez r;
	int when;
};

Alarm *alarms;
int now;

void
clocktask(void *v)
{
	for(;;){
		while(taskyield() > 0)
			;
		assert(alarms != 0);
		now = alarms->when;
		taskwakeup(&alarms->r);
		alarms = alarms->next;
	}
}

void
delay(int ms)
{
	Alarm a, *b, **l;
	
	memset(&a, 0, sizeof a);
	a.when = now+ms;
	for(l=&alarms; (b=*l) && b->when < a.when; l=&b->next)
		;
	a.next = *l;
	*l = &a;
	tasksleep(&a.r);
}


/*
 * Testing.
 */

enum { STACK = 32768 };

Channel *c;

void
delaytask(void *v)
{
	delay((int)v);
	printf("awake after %d ms - current time %d\n", (int)v, now);
	chansendul(c, 0);
}

void
taskmain(int argc, char **argv)
{
	int i, n;
	
	taskcreate(clocktask, 0, STACK);

	c = chancreate(sizeof(unsigned long), 0);

	n = 0;
	for(i=1; i<argc; i++){
		n++;
		taskcreate(delaytask, (void*)atoi(argv[i]), STACK);
	}

	/* wait for n tasks to finish */
	for(i=0; i<n; i++)
		chanrecvul(c);
	taskexitall(0);
}