chrono

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/*
 * This file is part of the µOS++ project (https://micro-os-plus.github.io/).
 * Copyright (c) 2016-2025 Liviu Ionescu. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software
 * for any purpose is hereby granted, under the terms of the MIT license.
 *
 * If a copy of the license was not distributed with this file, it can
 * be obtained from https://opensource.org/licenses/mit.
 */
 
#ifndef CMSIS_PLUS_CHRONO_CLOCKS_H_
#define CMSIS_PLUS_CHRONO_CLOCKS_H_
 
// ----------------------------------------------------------------------------
 
#include <cmsis-plus/rtos/os.h>
 
#include <chrono>
 
// ----------------------------------------------------------------------------
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wc++98-compat"
#pragma clang diagnostic ignored "-Wdocumentation-unknown-command"
#endif
 
// ----------------------------------------------------------------------------
 
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
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wc++98-compat"
// error: 'long long' is incompatible with C++98
// [-Werror,-Wc++98-compat-pedantic]
#pragma clang diagnostic ignored "-Wc++98-compat-pedantic"
#pragma clang diagnostic ignored "-Wreserved-identifier"
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Waggregate-return"
#pragma GCC diagnostic ignored "-Wuseless-cast"
#endif
 
      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
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wreserved-identifier"
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Waggregate-return"
#endif
 
      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
 
      // ----------------------------------------------------------------------
 
    } /* namespace chrono */
  } /* namespace estd */
} /* namespace os */
 
#pragma GCC diagnostic pop
 
// ----------------------------------------------------------------------------
 
#endif /* CMSIS_PLUS_CHRONO_CLOCKS_H_ */