#define LIGHT		IN_1
#define MOTOR		OUT_A

#define THRESHOLD	50

#define PowerDownDelay(minutes)		asm { 0xb1, (minutes) }

int curr_watch;
int old_watch;
int tmp;
int state;

sub step
{
	if (state == 0) {
		if (LIGHT < THRESHOLD) {
			Rev(MOTOR, 1);
			while (LIGHT < THRESHOLD);
			Off(MOTOR);
		}
		state = 1;
	} else {
		if (LIGHT > THRESHOLD) {
			Rev(MOTOR, 1);
			while (LIGHT > THRESHOLD);
			Off(MOTOR);
		}
		state = 0;
	}
}

task main
{
	Sensor(LIGHT, IN_LIGHT);

	/* Uncomment the next line to prevent the RCX from
	   falling asleep after the default 15 minutes.
	   Supplying power from an AC adapter is recommended. */
	/* PowerDownDelay(0); */
	Display(0);
	old_watch = Watch();
	state = 0;

	while(1 == 1) {
		curr_watch = Watch();
		if( curr_watch != old_watch ) {
			old_watch = curr_watch;
			/* We only want to step four times each five
			   minutes, for 48 steps per hour.  Don't
			   step on minutes that are multiples of 5. */
			tmp = (curr_watch / 5) * 5;
			if (tmp != curr_watch) {
				step();
			}
		}
	}
}