detect pin mode possible?

Projects Programming
6

I think it is simpler that I initially thought, it was a good idea to look at arduino/wiring_digital.c where I found the definition of pinMode():

void pinMode(uint8_t pin, uint8_t mode)
{
	uint8_t bit = digitalPinToBitMask(pin);
	uint8_t port = digitalPinToPort(pin);
	volatile uint8_t *reg, *out;

	if (port == NOT_A_PIN) return;

	// JWS: can I let the optimizer do this?
	reg = portModeRegister(port);
	out = portOutputRegister(port);

	if (mode == INPUT) { 
		uint8_t oldSREG = SREG;
                cli();
		*reg &= ~bit;
		*out &= ~bit;
		SREG = oldSREG;
	} else if (mode == INPUT_PULLUP) {
		uint8_t oldSREG = SREG;
                cli();
		*reg &= ~bit;
		*out |= bit;
		SREG = oldSREG;
	} else {
		uint8_t oldSREG = SREG;
                cli();
		*reg |= bit;
		SREG = oldSREG;
	}
}

that was easily reversed to a "getter":

uint8_t getPinMode(uint8_t pin)
{
  uint8_t bit = digitalPinToBitMask(pin);
  uint8_t port = digitalPinToPort(pin);
  volatile uint8_t *reg = portModeRegister(port);

  if (*reg & bit) {
    return OUTPUT;
  } else {
    volatile uint8_t *out = portOutputRegister(port);
    if (*out & bit) {
      return INPUT_PULLUP;
    } else {
      return INPUT;
    }
  }
}

this compiles but I can't test it now. I'm still not sure about the "oldSREG = SREG" trick and the CLI that are used in pinMode()