#include "Arduino.h"
#define ROT_A PD2
#define ROT_A_MASK _BV(ROT_A)
#define ROT_B PD3
#define ROT_B_MASK _BV(ROT_B)

#define VOL_DOWN PB1
#define VOL_DOWN_MASK _BV(VOL_DOWN)
#define VOL_UP PB2
#define VOL_UP_MASK _BV(VOL_UP)

static boolean r          = false;
char a, d                 = 0;
volatile unsigned long l  = 0;
unsigned long p           = 0;
unsigned char s           = 0;

void vol_set(char direction) {
  if (d != direction){
    s = 0;
  }
  if (s > 6){
    if (direction < 0) {
      Serial.println("VOLUME DOWN");
    } else {
      Serial.println("VOLUME UP");
    }
    s = 0;
  }
  d = direction;
  s++;
}

ISR(INT0_vect) {
  r = true;
  l = millis();
}

void setup() {
  DDRD |= (!ROT_A_MASK | !ROT_B_MASK);
  DDRB |= (VOL_DOWN_MASK | VOL_DOWN_MASK);
  PORTD |= (ROT_A_MASK | ROT_B_MASK);
  EICRA |= _BV(ISC00);
  EIMSK |= _BV(INT0);
  sei();
  Serial.begin(9600);
}
void loop() {
  unsigned long c = millis();

  if((c-l > 1200) && s !=0){
    s = 0;
  }

  while (r) {
    uint8_t x = 0;

    x = (bit_is_clear(PIND, ROT_A) << 1) | bit_is_clear(PIND, ROT_B);

    if (x == 0 && (a == 2 || a == 3)) {
      vol_set(-1);
    } else if (x == 1 && (a == 2 || a == 3)) {
      vol_set(1);
    } else if (x == 2 && (a == 0 || a == 1)) {
      vol_set(1);
    } else if (x == 3 && (a == 0 || a == 1)) {
      vol_set(-1);
    } else {
      //Serial.println("debounced");
    }
    a = x;
    r = false;
  }
}