Debounce a button

ButtonDebounce.ino

#define DEBOUNCE 15
#define DMASK ((uint16_t)(1<<DEBOUNCE)-1)
#define DF (1<<(uint16_t)(DEBOUNCE-1))
#define DR (DMASK-DF)

// macro for detection of raising edge and debouncing
#define DRE(signal, state) ((state=((state<<1)|(signal&1))&DMASK)==DR)

// macro for detection of falling edge and debouncing
#define DFE(signal, state) ((state=((state<<1)|(signal&1))&DMASK)==DF)

#define BUTTON_PIN 7
uint16_t pinStatus;

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
}

void loop() {
	if(DFE(digitalRead(BUTTON_PIN), pinStatus)) {
		// do stuff
	}
}