void setup() {
  // put your setup code here, to run once:
  volatile char *dirf;
  dirf = 0x30;
  *dirf = 0xFF;
}

void loop() {
  // put your main code here, to run repeatedly:
  // Glow the LEDs in following order
  // 3,7 delay – 2,6 delay – 1,5 delay – 0,4 delay
  volatile char *output, x;
  volatile long i;
  char leds[8] = {0x01, 0x04, 0x02, 0x08, 0x10, 0x40, 0x20, 0x80};
  output = 0x31;
  //************************************
  // Glow the LEDs in following order
  // 3,7 delay – 2,6 delay – 1,5 delay – 0,4 delay
  //*output |= 0x88; // 3,7  
  //for (i = 0; i < 200000; i++);
  //*output |= 0x44; // 2,6 
  //for (i = 0; i < 200000; i++);
  //*output |= 0x22;  // 1,5 0010 0010
  //for (i = 0; i < 200000; i++);
  //*output |= 0x11; // 0,4
  //************************************
  // Glow the LEDs in following order
  // 0,4 delay – 1,5 delay – 2,6 delay – 3,7 delay
  //*output |= 0x11; // 0,4 
  //for (i = 0; i < 200000; i++);
  //*output |= 0x22; // 1,5  
  //for (i = 0; i < 200000; i++);
  //*output |= 0x44;  // 2,6 
  //for (i = 0; i < 200000; i++);
  //*output |= 0x88; // 3,7
  //************************************
  // Glow 0 to 7 LEDs with delay and 7 to 0 LEDs with delay
  //for (x = 0; x < 8; x++) {
  //  *output |= 1 << x;
  //  for (i = 0; i < 200000; i++);
  //}
  //*output = 0x00;
  //for (x = 7; x >= 0; x--) {
  //  *output |= 1 << x;
  //  for (i = 0; i < 200000; i++);
  //}
  //************************************
  // Glow 0,2,1,3,4,6,5,7 LEDs with delay
      //0000 0001 0x01 - 0000 0100 0x04 - 0000 0010 0x02 - 0000 1000 0x08 - 0000 0000 0x10
      //0100 0000 0x40 - 0010 0000 0x20 - 1000 0000 0x80
  for (x = 0; x < 8; x++) {
    *output |= leds[x];
    for (i = 0; i < 200000; i++);
  }
}