int b1;
int b2;
int b3;
int b4;

//int stat = 0;
unsigned char stat = 0;

void setup() {
  // configure digital pins as inputs
  pinMode(4, INPUT_PULLUP);
  pinMode(5, INPUT_PULLUP);
  pinMode(6, INPUT_PULLUP);
  pinMode(7, INPUT_PULLUP);
  //Serial.begin(9600);
  DDRA = 0b11111111; // activate PORTA as output
}

void loop() {
  // read BTNs status
  b1 = digitalRead(4);
  b2 = digitalRead(5);
  b3 = digitalRead(6);
  b4 = digitalRead(7);
  //stat = 10000 + b4 * 1000 + b3 * 100 + b2 * 10 + b1;
  //Serial.println(stat);
  //stat = (b4 << 5) | (b3 << 4) | (b4 << 3) | (b3 << 2) | (b2 << 1)| b1;
  //PORTA = stat;

  if(b4 == LOW){
    // button pressed - walk from right to left
    for (int i = 0; i < 6; i++)
    {
      stat = (1 << (5 - i));// shift led from right to left
      PORTA = stat; // display led stat on PORTA
      delay(200);
    }
  } else {
    //button not pressed - shift from left to right
     for (int i = 0; i < 6; i++)
    {
      stat = (1 << i);// shift led from left to right
      PORTA = stat; // display led stat on PORTA
      delay(200);
    }
  }

  delay(100);
}