chrono

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/*
 * This file is part of the µOS++ distribution.
 *   (https://github.com/micro-os-plus)
 * Copyright (c) 2016 Liviu Ionescu.
 *
 * 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.
 */

#ifndef CMSIS_PLUS_CHRONO_CLOCKS_H_
#define CMSIS_PLUS_CHRONO_CLOCKS_H_

// ----------------------------------------------------------------------------

#include <cmsis-plus/rtos/os.h>

#include <chrono>

// ----------------------------------------------------------------------------

namespace os
{
  namespace estd
  {
    namespace chrono
    {

      // ======================================================================

      template<typename T, typename = void>
        struct has_sleep_for : std::false_type
        {
        };

      template<typename T>
        struct has_sleep_for<T,
            decltype(std::declval<T>().has_sleep_for, void())> : std::true_type
        {
        };

      // ======================================================================
      // µOS++ SysTick clock.
      class systick_clock
      {
      public:

        using rep = rtos::clock_systick::timestamp_t;
        using sleep_rep = rtos::clock_systick::duration_t;
        using period = std::ratio<1, os::rtos::clock_systick::frequency_hz>;
        using duration = std::chrono::duration<rep, period>;
        using sleep_duration = std::chrono::duration<sleep_rep, period>;
        using time_point = std::chrono::time_point<systick_clock>;
        static constexpr bool is_steady
          { true };
        static constexpr bool has_sleep_for
          { true };

        static time_point
        now () noexcept;

        // --------------------------------------------------------------------
        // Extension to ISO

        static void
        sleep_for (sleep_rep ticks);

      };

      // Define a duration type, to be used in timeout expressions.
      using systicks = systick_clock::duration;

      //constexpr systicks
      //operator "" systicks (Ssstick_clock::rep); // C++14

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Waggregate-return"

      constexpr systicks
      operator"" _ticks (unsigned long long t)
      {
        return systicks (static_cast<systick_clock::rep> (t));
      }

#pragma GCC diagnostic pop

      // ======================================================================

      // µOS++ RTC.

      class realtime_clock
      {
      public:

        using rep = rtos::clock_rtc::timestamp_t;
        using sleep_rep = rtos::clock_rtc::duration_t;

        using period = std::ratio<1, 1>;
        using duration = std::chrono::duration<rep, period>;
        using sleep_duration = std::chrono::duration<sleep_rep, period>;

        using time_point = std::chrono::time_point<realtime_clock>;

        // Non-monotonic, may be adjusted back in time.
        static constexpr const bool is_steady
          { false };
        static constexpr bool has_sleep_for
          { true };

        static time_point
        now () noexcept;

        // --------------------------------------------------------------------
        // Extension to ISO

        static void
        sleep_for (sleep_rep);

        // Number of seconds from epoch (1 January 1970 00:00:00 UTC)
        // Must be initialised during startup with the value of now().
        // Realtime_clock::startup_time_point = Realtime_clock::now();
        static time_point startup_time_point;
      };

      // ======================================================================

      // The system_clock is basically derived from the SysTick counts.
      // The counter is monotonic, and normally should not be adjusted,
      // so the clock is steady.

      class system_clock
      {
      public:

        using duration = std::chrono::microseconds;
        using rep = duration::rep;
        using period = duration::period;
        using time_point = std::chrono::time_point<system_clock>;

        // Monotonic, never adjusted back in time.
        static constexpr const bool is_steady
          { true };

        static time_point
        now () noexcept;

        // It is the only C++ clock that has the ability to map its
        // time points to C-style time, and, therefore, to be displayed.
        static time_t
        to_time_t (const time_point& tp) noexcept;
        static time_point
        from_time_t (time_t t) noexcept;

      };

      // ======================================================================

      // To simplify things, we assumed the system clock is already steady.
      using steady_clock = system_clock;

      // ======================================================================

      // The high resolution clock is also based on SysTick, but also uses
      // the counter instant value, which gives 1 CPU cycle resolution.

      class high_resolution_clock
      {
      public:

        using duration = std::chrono::nanoseconds;
        using rep = duration::rep;
        using period = duration::period;
        using time_point = std::chrono::time_point<high_resolution_clock>;

        // Monotonic, never adjusted back in time.
        static constexpr const bool is_steady
          { true };

        static time_point
        now () noexcept;
      };

    } /* namespace chrono */
  } /* namespace estd */
} /* namespace os */

// ----------------------------------------------------------------------------
// Inline & template implementations.

namespace os
{
  namespace estd
  {
    namespace chrono
    {

      // ======================================================================

      inline void
      systick_clock::sleep_for (sleep_rep ticks)
      {
        rtos::sysclock.sleep_for (ticks);
      }

      // ======================================================================

      inline void
      realtime_clock::sleep_for (sleep_rep secs)
      {
        rtos::rtclock.sleep_for (secs);
      }

      // ======================================================================

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Waggregate-return"

      template<class _To, class Rep_T, class Period_T>
constexpr        typename std::enable_if<
        std::chrono::__is_duration<_To>::value, _To>::type
        ceil (std::chrono::duration<Rep_T, Period_T> d)
          {
            using namespace std::chrono;
            _To r = std::chrono::duration_cast<_To> (d);
            if (r < d)
              {
                ++r;
              }
            return r;
          }

#pragma GCC diagnostic pop

        // ----------------------------------------------------------------------
      ;
    // Avoid formatter bug
    } /* namespace chrono */
  } /* namespace estd */
} /* namespace os */

// ----------------------------------------------------------------------------

#endif /* CMSIS_PLUS_CHRONO_CLOCKS_H_ */