utl/include/utl/dev/gpio_dev.h

/*!
 * \file dev/gpio_dev.h
 * \brief
 *      A STM32 gpio wrapper class
 *
 * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
 *
 * <dl class=\"section copyright\"><dt>License</dt><dd>
 * The MIT License (MIT)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * </dd></dl>
 */

#ifndef utl_dev_gpio_dev_h__
#define utl_dev_gpio_dev_h__

#include <utl/core/impl.h>

namespace utl {

    /*!
     * CRTP class for gpio digital input-output.
     *
     * The derived class requirements are:
     *  - bool read_impl ()
     *  - void write_impl(bool)
     *
     * \tparam  Impl_t  The type of derived class
     */
    template <typename Impl_t>
    class DigitalInOut {
    public:
            _CRTP_IMPL(Impl_t);

        /*!
         * \name Object lifetime
         */
        //! @{
        protected:
            DigitalInOut() noexcept = default;
            ~DigitalInOut() = default;
            DigitalInOut(const DigitalInOut&)             = delete;   //!< No copy constructions
            DigitalInOut operator=(const DigitalInOut&)   = delete;   //!< No copies

        //! @}

        //! \name Public interface
        //! @{
        public:
            //! Reads the state of the pin. This is true for both input and output pins.
            //! \return     The state of the pin
            bool read () noexcept { return impl().read_impl (); }
            //! Write a new state to pin. If the pin is set for output, otherwise this state will remain
            //! to pin registers and reflect to the pin state if we select output mode
            void write (bool state) noexcept { impl().write_impl(state); }

            //! Implicit conversion to bool for reading operations
            operator bool () noexcept {
                return read();
            }
            //! Stream from bool for write operations
            DigitalInOut& operator<< (bool state) noexcept {
                write(state);
                return *this;
            }
            //! Right stream to bool for read operations
            DigitalInOut& operator>> (bool& state) noexcept {
                state = read();
                return *this;
            }
        //! @}
    };

    /*!
     * This definition enables the "data << pin" syntax for read operation
     *
     * \tparam Impl_t   The derived class type of the DigitalInOut
     *
     * \param lhs   Left hand site operand
     * \param rhs   Right hand site operand
     * \return      The read value
     */
    template<typename Impl_t>
    bool operator<<(bool& lhs, DigitalInOut<Impl_t>& rhs) noexcept {
        lhs = rhs.read();
        return lhs;
    }
}

#endif //#ifndef utl_dev_gpio_dev_h__