#include <LiquidCrystal.h>

#define Set1(R,b) R|=1<<b
#define Set0(R,b) R&=~(1<<b)
#define Get(R,b) (R&(1<<b))

LiquidCrystal lcd(13,12,11,10,9,8);
bool button = true;

volatile int col = 0;
char currentChar[] = {'A','B','C'};

void setup() {
  lcd.begin(16,2);
  PORTD |= 0b00011100;

  EIMSK |= (1<<0);//Set1(EIMSK,INT0);
  EICRA |= (1<<0); //Set1(EICRA,ISC00);
  EICRA |= (1<<1); //Set0(EICRA,ISC01);

  EIMSK |= (1<<1); //Set1(EIMSK,INT1);
  EICRA |= (1<<2); //Set1(EICRA,ISC10);
  EICRA |= (1<<3); //Set0(EICRA,ISC11);

  Set1(SREG,7);
}

void loop() {
  
  if(Get(PIND,4) == 0 && button){
    lcd.setCursor(0,1);
    lcd.print("Volba:");
    lcd.setCursor(7,1);
    lcd.print(currentChar[col]);

    button = false;
  }else if(Get(PIND,4) != 0 && !button){

    button = true;
  }
  if(col == 0){
    lcd.setCursor(0,0);
    lcd.print("A      b      c");
  }else if(col == 1){
    lcd.setCursor(0,0);
    lcd.print("a      B      c");
  }else if(col == 2){
    lcd.setCursor(0,0);
    lcd.print("a      b      C");
  }
  
}

ISR(INT0_vect)
{
  if(col < 2)
    col++;
  else
    col = 0;
}

ISR(INT1_vect){
  if(col > 0)
    col--;
  else
    col = 2;
}