port_pin.h

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#pragma once
 
#include <Arduino.h>
 
// Automatic type deduction 
namespace type_detection_detail {
  // These are used for automatic type detection *at compile time* and are never executed.
 
  // Get the return type of a function call
  template <typename R, typename... Args> R return_type_of(R(*)(Args...));
 
  // portOutputRegister() and digitalPinToBitMask() on AVR is a GCC return expression, which needs to
  // be wrapped in a function to be used in this context.
  static inline auto detectPortRegisterType(void) { return portOutputRegister(digitalPinToPort(0)); };
  static inline auto detectDigitalPinToBitMask(void) { return digitalPinToBitMask(0); };
}
 
struct port_pin_t
{
  port_pin_t() = default;
 
  port_pin_t(uint8_t pinNum, uint8_t mode);
 
  bool isValid(void) const {
    return _port!=NULL_PORT;
  }
 
  // LCOV_EXCL_START
  bool isPinHigh(void) const noexcept {
    return isValid() ? 
#if defined(UNIT_TEST)
    _pinState
#else
    (*_port & _mask) != 0
#endif    
     : false;
  }
  // LCOV_EXCL_STOP
 
  bool isPinLow(void) const noexcept {
    return !isPinHigh();
  }
 
  void setPinHigh(void) noexcept;
 
  void setPinLow(void) noexcept;
 
private:
 
  using port_register_t = decltype(type_detection_detail::return_type_of(&type_detection_detail::detectPortRegisterType));
 
  using pin_mask_t = decltype(type_detection_detail::return_type_of(&type_detection_detail::detectDigitalPinToBitMask));
 
  static constexpr port_register_t NULL_PORT = {nullptr};
 
  port_register_t _port = NULL_PORT;
  pin_mask_t _mask = {0};
#if defined(UNIT_TEST)
  bool _pinState = LOW;
#endif
};