typedef unsigned char uint8_t;

#define DDRB (*(volatile uint8_t*)0x37)
#define PORTB (*(volatile uint8_t*)0x38)

void wait(void) {
	volatile int i;
 	for (i=0; i<30000; ++i)
		/*empty*/;
}

int main() {
	void wait();
	uint8_t c1, c2, i;
	
	DDRB=0xFF;
	while (1) {
		c1=0x80;
		c2=0x01;
		for (i=0;i<4;i++) {
			wait();
			PORTB=~(c1|c2);
			c1>>=1;
			c2<<=1;
		}
	}
	return 0;
}