Arcade Joystick with Teensy 3.0

joystick.ino

/* Arcade Keyboard-Joystick */

#include <usb_keyboard.h>

#define NUM_BUTTONS 8
int keys[NUM_BUTTONS] = {KEY_RIGHT, KEY_UP, KEY_DOWN, KEY_LEFT, KEY_ENTER, KEY_SPACE, KEY_LEFT_ALT, KEY_Z};
int mask = 0;
int i = 0;

void setup() {
  for (i = 0; i < NUM_BUTTONS; i++) {
    pinMode(i, INPUT_PULLUP);
  }
  delay(1000);
}

void loop() {
  for (i = 0; i < NUM_BUTTONS; i++) {
    if (digitalRead(i) == LOW) {
      if (!(mask & (1 << i))) {
        Keyboard.press(keys[i] | (0x40 << 8));
        mask |= (1 << i);
      }
    } else {
      if ((mask & (1 << i))) {
        Keyboard.release(keys[i] | (0x40 << 8));
        mask &= ~(1 << i);
      }
    }
  }
  delay(2);
}