URS_L07Z05

#define F_CPU 7372800UL

#include <avr/io.h>
#include <util/delay.h>

void blink(uint8_t cnt) {
    if (cnt <= 3) {
        PORTA = PORTA & ~_BV(cnt) & ~_BV(7-cnt);
    } else {
        cnt %= 4;
        PORTA = PORTA | _BV(cnt+4) | _BV(3-cnt);
    }
}

int main(void) {
    DDRA = 0xff;
    PORTA = 0xff;
    uint8_t cnt = 0;

    while (1) {
        blink(cnt);
        cnt = (cnt + 1) % 8;
    //  _delay_ms(325);
    }
}