#define SWITCH	IN_1
#define LIGHT	IN_2

#define X	OUT_A
#define Y	OUT_C
#define Z	OUT_B	/* Rev = down */

#define DX	10
#define DY	10

#define GREY	50

#define LOGSIZE	200

int depth;
int eol;

sub probe
{
	depth = 0;

	Rev(Z, 7);
	wait (SWITCH == 0);
	wait (SWITCH == 1) {
		depth+=1;
	}
	Fwd(Z, 7);
	wait (SWITCH == 0);
	wait (SWITCH == 1);
	Off(Z);
	Datalog(depth);
}

task main
{
	Sensor(SWITCH, IN_SWITCH);
	Sensor(LIGHT, IN_LIGHT);

	probe();
	SetDatalog(0);			/* clear the log */
	SetDatalog(LOGSIZE);
	eol = 0;			/* end-of-line */

	while (1 == 1) {
		Rev(X, 7);
		wait (LIGHT > GREY);
		wait (LIGHT < GREY);
		Fwd(X, 7);
		wait (LIGHT > GREY);
		Off(X);

		while (LIGHT > GREY) {
			probe();
			Fwd(X, 7);
			Sleep(DX);
			Off(X);
		}
		Datalog(eol);

		Rev(Y, 7);
		Sleep(DY);
		Off(Y);
	}
}