// arduino tutorial for this topic:  https://docs.arduino.cc/retired/hacking/software/PortManipulation/
// documentation of Atmega 328p:     https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf

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

int main(){

  // diode configuration
  DDRB |= (1<<DDB2) | (1<<DDB3) | (1<<DDB4) | (1<<DDB5);  						  // Direction of port line (1 - output)
  PORTB |= (1<<PORTB2) | (1<<PORTB3) | (1<<PORTB4) | (1<<PORTB5);   			  // output value for output mode (1 - high do not light, 0 - lod light)
  
  // BUTTON CONTROLLER
  DDRD &= ~(1<<DDD0) | ~(1<<DDD1) | ~(1<<DDD2) | ~(1<<DDD3);   	      			  // direction - input
  PORTD |= (1<<PORTD0) | (1<<PORTD1) | (1<<PORTD2) | (1<<PORTD3);				  // pin to VCC (internal pullup)

  while(1){
		if (!(PIND & 1<<PIND3)) { // if S1 button is pressed counter up
		  PORTB = PORTB-1;
		  _delay_ms(100);
		}
		if (!(PIND & 1<<PIND2)) { // if S1 button is pressed counter up
		  PORTB = PORTB+1;
		  _delay_ms(100);
		}
		if (!(PIND & 1<<PIND1)) { // if S1 button is pressed counter up
		  PORTB = 255;
		  _delay_ms(100);
		}
		if (!(PIND & 1<<PIND0)) { // if S1 button is pressed counter up
		  PORTB = 0;
		  _delay_ms(100);
		}
	}
}