Pi counter for ATtiny84

picounter.c

/* picounter.c
  Counts digits of pi in binary.
*/

void setup() {
  pinMode(0, OUTPUT);
  pinMode(1, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
}

int pi[] = {3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2,3,8,4,6,2,6,4,3,3,8,3,2,7,9,5,0,2,8,8,4,1,9,7,1,6,9,3,9,9,3,7,5,1,0,5,8,2,0,9,7,4,9,4,4,5,9,2,3,0,7,8,1,6,4,0,6,2,8,6,2,0,8,9,9,8,6,2,8,0,3,4,8,2,5,3,4,2,1,1,7,0,6,7,9,8,2,1,4,8,0,8,6,5,1,3,2,8,2,3,0,6,6,4,7,0,9,3,8,4,4,6,0,9,5,5,0,5,8,2,2,3,1,7,2,5,3,5,9,4};
int len = 146;

int power2(int n) {
  int ret = 1;
  for (int i = 0; i < n; i++) {
    ret *= 2;
  }
  return ret;
}

int displayNum(int n) {
  for (int i = 0; i<4; i++) {
    int mask = power2(i);
    if ((n & mask) == mask) {
      digitalWrite(i, HIGH);
    } else {
      digitalWrite(i, LOW);
    } 
  }
}

int i = 0;

void loop() {
  for (i = 0; i<len; i++) {  
    displayNum(pi[i]);    
    delay(1000);       
  }    
}