1D pong on atmega8 (WIP)

gistfile1.cpp

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

int dir = 0;

int main() {
	TIMSK |= (1<<TOIE0);
	DDRD = (1<<PD3);
	PORTD |= (1<<PD3) | (1<<PD2);
	MCUCR |= (1<<ISC11);
	GICR |= (1<<INT1);
	TCCR0 |= (1<<CS02) | (0<<CS01) | (0<<CS00);
	DDRB = 0xFF;
	PORTB = 1;
	sei();
	while(1);
}

ISR(SIG_OVERFLOW0) {
	if (dir == 0) {
		if (PORTB<<1 > 0b10000000) PORTB = 1; else PORTB <<= 1;
	} else {
		if (PORTB>>1 < 1) PORTB = 0b10000000; else PORTB >>= 1;
	}
}

ISR(SIG_INTERRUPT0) {
	if (dir == 1) {
		dir = 0;
	}
}

ISR(SIG_INTERRUPT1) {
	if (dir == 0) {
		dir = 1;
	}
}