#include <avr/io.h>
//#include <avr/iotn2313a.h>
#include <util/delay.h>
#include <avr/interrupt.h>

#define PCIE1 3

uint8_t digits[] = {
        //      63,6,91,79,102,109,125,7,127,111};
        119,66,93,94,106,62,63,82,127,126};
volatile uint8_t loop;

/*ISR(PCINT_A_vect, ISR_NAKED) {
        loop++; reti();
}*/

ISR(TIMER0_OVF_vect)
{
        loop++;
}

/*ISR_ALIASOF(PCINT_A_vect));
EMPTY_INTERRUPT(BADISR_vect);
*/

void showDigit(uint8_t pos, uint8_t digit) {
        PORTB = digits[digit];
        PORTD = 0b11111 & ((uint8_t) ~_BV(pos));
}

void showNumber(uint8_t num) {
        uint8_t i = 0;
        do {
                //PORTB = digits[i];
                //PORTD = ((uint8_t) ~_BV(num % 10));
                showDigit(i++, num % 10);
                num /= 10;
                i++;
        } while (num > 0);
}


int main(void) {
        // ports output
        DDRB = 0xFF; // all pins
        DDRD = 0xFF; // are outputs
        DDRA = 0x01;

        //timer
        GTCCR           = _BV(PSR10);  // clear timer
        TCCR0B  = _BV(CS00) | _BV(CS02); // prescaler 1/1024
        TIMSK           = _BV(TOIE0);   // timer overflow interrupt
/*
        // interrupt
        GIMSK           |= _BV(PCIE1);   // pin change interrupt
        PCMSK1  |= _BV(PCINT9); // pin change for PINA2
        */
        sei();  // enable interrupts

        while (1) {
                //_delay_ms(500);
                showNumber(loop);
        }

}