#include <wiringPi.h>

int main()
{
	const int motor_a=26;
	const int motor_b=23;
	const int button=21;

	wiringPiSetup();
	pinMode(button, INPUT);
	pinMode(motor_a, OUTPUT);
	pinMode(motor_b, OUTPUT);
	digitalWrite(motor_a, LOW);
	digitalWrite(motor_b, LOW);

	int input_prev=HIGH;
	int motor=0;

	while(1){
		int input_cur=digitalRead(button);

		if(input_prev==HIGH && input_cur==LOW){
			++motor;

			if(motor>3)
				motor=0;

			if(motor==0){
				digitalWrite(motor_a, LOW);
				digitalWrite(motor_b, LOW);
			} else if(motor==1){
				digitalWrite(motor_a, HIGH);
				digitalWrite(motor_b, LOW);
			} else if(motor==2){
				digitalWrite(motor_a, LOW);
				digitalWrite(motor_b, LOW);
			} else if(motor==3){
				digitalWrite(motor_a, LOW);
				digitalWrite(motor_b, HIGH);
			}
		}

		if(input_prev!=input_cur)
			input_prev=input_cur;

		delay(20);
	}

	return 0;
}