text: /* Arduino DigitalIO Library
   * Copyright (C) 2013 by William Greiman
   *
   * This file is part of the Arduino DigitalIO Library
   *
   * This Library is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * This Library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with the Arduino DigitalIO Library.  If not, see
   * <http://www.gnu.org/licenses/>.
   */
  /**
   * @file
   * @brief Digital AVR port I/O with runtime pin number.
   *
   * @defgroup runtimeDigital Runtime Pin I/O
   * @ingroup internals
   * @details  Two Wire Interface library.
   * @{
   */
  #ifndef PinIO_h
  #define PinIO_h
  #include <util/atomic.h>
  #include <avr/io.h>
  /** @brief Helper macro for complex inline attributes */
  #define ALWAYS_INLINE inline __attribute__((always_inline))
  //------------------------------------------------------------------------------
  /**
   * @class PinIO
   * @brief AVR port I/O with runtime pin numbers.
   */
  class PinIO
  {
  public:
  	/** Create a PinIO object with no assigned pin. */
  	PinIO() : bit_(0), mask_(0XFF) {}
  	/** Constructor
  	 * @param[in] pin Pin assigned to this object.
  	 */
  	explicit PinIO(uint8_t pin);
  	/** Initialize pin bit mask and port address.
  	 * @param[in] pin Arduino board pin number.
  	 * @return true for success or false if invalid pin number.
  	 */
  	bool begin(uint8_t pin);
  	/** Configure the pin
  	 *
  	 * @param[in] mode Configure as output mode if true else input mode.
  	 * @param[in] data For output mode set pin high if true else low.
  	 *                 For input mode enable 20K pullup if true else Hi-Z.
  	 *
  	 * This function may be used with interrupts enabled or disabled.
  	 * The previous interrupt state will be restored.
  	 */
  	void config(bool mode, bool data);
  	//----------------------------------------------------------------------------
  	/** @return Pin's level */
  	ALWAYS_INLINE bool read()
  	{
  		return *pinReg_ & bit_;
  	}
  	//----------------------------------------------------------------------------
  	/** toggle a pin
  	 *
  	 * If the pin is in output mode toggle the pin's level.
  	 * If the pin is in input mode toggle the state of the 20K pullup.
  	 */
  	ALWAYS_INLINE void toggle()
  	{
  		*pinReg_ = bit_;
  	}
  	//============================================================================
  	/**
  	 * Set pin high if output mode or enable 20K pullup if input mode.
  	 *
  	 * This function must be called with interrupts disabled.
  	 * This function will not change the interrupt state.
  	 */
  	ALWAYS_INLINE void highI()
  	{
  		writeI(1);
  	}
  	/**
  	 * Set pin low if output mode or disable 20K pullup if input mode.
  	 *
  	 * This function must be called with interrupts disabled.
  	 * This function will not change the interrupt state.
  	 */
  	ALWAYS_INLINE void lowI()
  	{
  		writeI(0);
  	}
  	/**
  	 * Set pin mode
  	 * @param[in] mode if true set output mode else input mode.
  	 *
  	 * mode() does not enable or disable the 20K pullup for input mode.
  	 *
  	 * This function must be called with interrupts disabled.
  	 * This function will not change the interrupt state.
  	 */
  	ALWAYS_INLINE void modeI(bool mode)
  	{
  		volatile uint8_t* ddrReg = pinReg_ + 1;
  		*ddrReg = mode ? *ddrReg | bit_ : *ddrReg & mask_;
  	}
  	/**  Write pin.
  	 *
  	 * @param[in] level If output mode set pin high if true else low.
  	 * If input mode enable 20K pullup if true else disable pullup.
  	 *
  	 * This function must be called with interrupts disabled.
  	 * This function will not change the interrupt state.
  	 */
  	ALWAYS_INLINE void writeI(bool level)
  	{
  		*portReg_ = level ? *portReg_ | bit_ : *portReg_ & mask_;
  	}
  	//============================================================================
  	/**
  	 * Set pin level high if output mode or enable 20K pullup if input mode.
  	 *
  	 * This function will enable interrupts.  This function should not be
  	 * called in an ISR or where interrupts are disabled.
  	 */
  	ALWAYS_INLINE void high()
  	{
  		ATOMIC_BLOCK(ATOMIC_FORCEON) {
  			highI();
  		}
  	}
  	/**
  	 * Set pin level low if output mode or disable 20K pullup if input mode.
  	 *
  	 * This function will enable interrupts.  This function should not be
  	 * called in an ISR or where interrupts are disabled.
  	 */
  	ALWAYS_INLINE void low()
  	{
  		ATOMIC_BLOCK(ATOMIC_FORCEON) {
  			lowI();
  		}
  	}
  	/**
  	 * Set pin mode
  	 * @param[in] pinMode if true set output mode else input mode.
  	 *
  	 * mode() does not enable or disable the 20K pullup for input mode.
  	 *
  	 * This function will enable interrupts.  This function should not be
  	 * called in an ISR or where interrupts are disabled.
  	 */
  	ALWAYS_INLINE void mode(bool pinMode)
  	{
  		ATOMIC_BLOCK(ATOMIC_FORCEON) {
  			modeI(pinMode);
  		}
  	}
  	/**  Write pin.
  	 *
  	 * @param[in] level If output mode set pin high if true else low.
  	 * If input mode enable 20K pullup if true else disable pullup.
  	 *
  	 * This function will enable interrupts.  This function should not be
  	 * called in an ISR or where interrupts are disabled.
  	 */
  	ALWAYS_INLINE void write(bool level)
  	{
  		ATOMIC_BLOCK(ATOMIC_FORCEON) {
  			writeI(level);
  		}
  	}
  	//----------------------------------------------------------------------------
  private:
  	uint8_t bit_;
  	uint8_t mask_;
  	volatile uint8_t* pinReg_;
  	volatile uint8_t* portReg_;
  };
  #endif  // PinIO_h
  /** @} */