#include <avr/io.h>
#include <avr/interrupt.h>
volatile uint8_t cycleCounter = 0;
volatile uint8_t counter = 0;

unsigned char chart_tab[] = {
    0x0F, //0
    0x06, //1
    0x5B, //2
    0x4F, //3
    0x66, //4
    0x6D, //5
    0x7D, //6
    0x07, //7
    0x7F, //8
    0x6F, //9
    0x77, //A
    0x7C, //B
    0x39, //C
    0x5E, //D
    0x79, //E
    0x71, //F
};

ISR(TIMER1_COMPA_vect) {
    TCCR1B &= 0b11111000; // Wyłączenie timera
    TCNT1 = 0;
    GIFR |= (1 << INTF0);
    GICR |= (1 << INT0);

    if (cycleCounter != 0) {
      cycleCounter--;
      PORTA = ~(_BV(counter % 4));
      TCCR1B |= (1 << CS12);
      return;
    }

    asm("nop");

    if (PINA >> 4 != 0b00001111) {
        uint8_t mask = 1;
        for (uint8_t row = 0; row < 4; row++) {
            if ((PINA >> 4 & mask) == 0) {
                PORTD = ~(chart_tab[counter * 4 + (row % 4)]);
            }
            mask = mask << 1;
        }
    }
    counter++;
    if (counter >= 4) {
        counter = 0;
    }
    cycleCounter = 100;
    TCCR1B |= (1 << CS12); // Włączenie timera
}
void initTimer() {
    TCNT1   = 0;
    TCCR1B |= (1 << WGM12);
    OCR1A   = 1; // Przepełnienie co 20ms
    TIMSK  |= (1 << OCIE1A);
    TCCR1B |= (1 << CS12);

    PORTD = 0b10000000;
}
int main() {
    cli();
     DDRD  = 0xFF; // Ustawienie PORTD na wyjście dla diód
     DDRA  = 0x0F; // Pierwsza połowa PORTA to wiersze, a druga to kolumny klawiatury
     PORTA = 0xFF; // Podciągnięcie PORTA
     MCUCR |= (1 << ISC01);
     initTimer();
     sei();
     while(1);
}