os-core.cpp

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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.
 */

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

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

namespace
{
#if defined(OS_HAS_INTERRUPTS_STACK)
// Object used to manage the interrupts stack.
  class os::rtos::thread::stack interrupts_stack;
#endif /* defined(OS_HAS_INTERRUPTS_STACK) */
  ;
// Avoid formatter bug
}

namespace os
{
  namespace rtos
  {

    namespace scheduler
    {
      bool is_started_ = false;

#if 0

      state_t lock_state_ = state::init;
#endif

#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wglobal-constructors"
#pragma clang diagnostic ignored "-Wexit-time-destructors"
#endif

      // top_threads_list top_threads_list_;
      thread::threads_list top_threads_list_;

#pragma GCC diagnostic pop

#if !defined(OS_USE_RTOS_PORT_SCHEDULER)

      bool is_preemptive_ = false;

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpadded"
      // A small kludge to provide a temporary errno before
      // the first real thread is created.
      typedef struct {
        void* vtbl;
        void* name_;
        // errno is the first thread member, so right after the name.
        int errno_;
      } tiny_thread_t;
#pragma GCC diagnostic pop

      // Ensure the tiny thread is large enough to have the errno
      // member in the same location.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Winvalid-offsetof"
      static_assert(offsetof(tiny_thread_t, errno_) == offsetof(thread, errno_), "adjust tiny_thread_t members");
#pragma GCC diagnostic pop

#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wmissing-variable-declarations"
#endif
      tiny_thread_t tiny_thread;
#pragma GCC diagnostic pop

      thread* volatile current_thread_ = reinterpret_cast<thread*>(&tiny_thread);

#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wglobal-constructors"
#pragma clang diagnostic ignored "-Wexit-time-destructors"
#endif
      internal::ready_threads_list ready_threads_list_;
#pragma GCC diagnostic pop
#endif

#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wglobal-constructors"
#pragma clang diagnostic ignored "-Wexit-time-destructors"
#endif
      internal::terminated_threads_list terminated_threads_list_;
#pragma GCC diagnostic pop

      result_t
      initialize (void)
      {
#if defined(OS_TRACE_RTOS_SCHEDULER)
        trace::printf ("scheduler::%s() \n", __func__);
#endif

        // Don't call this from interrupt handlers.
        os_assert_err(!interrupts::in_handler_mode (), EPERM);

#if defined(OS_USE_RTOS_PORT_SCHEDULER)

        return port::scheduler::initialize ();

#else

        port::scheduler::initialize ();

        return result::ok;
#endif
      }

      [[noreturn]] void
      start (void)
      {
        trace::printf ("scheduler::%s() \n", __func__);

        // Don't call this from interrupt handlers.
        os_assert_throw(!interrupts::in_handler_mode (), EPERM);

        sysclock.start ();
        hrclock.start ();

        rtclock.start ();

#if defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CONTEXT_SWITCHES)

        scheduler::statistics::context_switches_ = 0;

#endif /* defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CONTEXT_SWITCHES) */

#if defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CPU_CYCLES)

        scheduler::statistics::cpu_cycles_ = 0;
        scheduler::statistics::switch_timestamp_ = hrclock.now ();

#endif /* defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CPU_CYCLES) */

#if !defined(OS_USE_RTOS_PORT_SCHEDULER)
        is_preemptive_ = OS_BOOL_RTOS_SCHEDULER_PREEMPTIVE;
#endif /* defined(OS_USE_RTOS_PORT_SCHEDULER) */

        is_started_ = true;

        port::scheduler::start ();
      }

      bool
      preemptive (bool state)
      {
#if defined(OS_TRACE_RTOS_SCHEDULER)
        trace::printf ("scheduler::%s(%d) \n", __func__, state);
#endif
        // Don't call this from interrupt handlers.
        os_assert_throw(!interrupts::in_handler_mode (), EPERM);

#if defined(OS_USE_RTOS_PORT_SCHEDULER)

        return port::scheduler::preemptive(state);

#else
        bool tmp;

          {
            // ----- Enter critical section -----------------------------------
            interrupts::critical_section ics;

            tmp = is_preemptive_;
            is_preemptive_ = state;
            // ----- Exit critical section ------------------------------------
          }

        return tmp;
#endif
      }

      thread::threads_list&
      children_threads (thread* th)
      {
        if (th == nullptr)
          {
            return top_threads_list_;
          }
        else
          {
            return th->children_;
          }
      }

    /*
     * @var const state_t critical_section::state_
     * @details
     * The variable is constant, after being set by the constructor no
     * further changes are possible.
     *
     * The variable type usually is a `bool`, but a counter is also
     * possible if the scheduler uses a recursive lock.
     */

    } /* namespace scheduler */

    namespace scheduler
    {
      void
      internal_link_node (internal::waiting_threads_list& list,
                          internal::waiting_thread_node& node)
      {
        // Remove this thread from the ready list, if there.
        port::this_thread::prepare_suspend ();

        // Add this thread to the node waiting list.
        list.link (node);
        node.thread_->waiting_node_ = &node;

        node.thread_->state_ = thread::state::suspended;
      }

      void
      internal_unlink_node (internal::waiting_thread_node& node)
      {
          {
            // ----- Enter critical section -----------------------------------
            interrupts::critical_section ics;

            // Remove the thread from the node waiting list,
            // if not already removed.
            node.thread_->waiting_node_ = nullptr;
            node.unlink ();
            // ----- Exit critical section ------------------------------------
          }
      }

      void
      internal_link_node (internal::waiting_threads_list& list,
                          internal::waiting_thread_node& node,
                          internal::clock_timestamps_list& timeout_list,
                          internal::timeout_thread_node& timeout_node)
      {
        // Remove this thread from the ready list, if there.
        port::this_thread::prepare_suspend ();

        // Add this thread to the node waiting list.
        list.link (node);
        node.thread_->waiting_node_ = &node;

        node.thread_->state_ = thread::state::suspended;

        // Add this thread to the clock timeout list.
        timeout_list.link (timeout_node);
        timeout_node.thread.clock_node_ = &timeout_node;
      }

      void
      internal_unlink_node (internal::waiting_thread_node& node,
                            internal::timeout_thread_node& timeout_node)
      {
        // ----- Enter critical section ---------------------------------------
        interrupts::critical_section ics;

        // Remove the thread from the clock timeout list,
        // if not already removed by the timer.
        timeout_node.thread.clock_node_ = nullptr;
        timeout_node.unlink ();

        // Remove the thread from the node waiting list,
        // if not already removed.
        node.thread_->waiting_node_ = nullptr;
        node.unlink ();
        // ----- Exit critical section ----------------------------------------
      }

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

#if !defined(OS_USE_RTOS_PORT_SCHEDULER)

      void
      internal_switch_threads (void)
      {
#if defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CPU_CYCLES)

        // Get the high resolution timestamp.
        clock::timestamp_t now = hrclock.now ();

        // Compute duration since previous context switch.
        // Assume scheduler is not disabled for very long.
        rtos::statistics::duration_t delta =
            static_cast<rtos::statistics::duration_t> (now
                - scheduler::statistics::switch_timestamp_);

        // Accumulate durations to scheduler total.
        scheduler::statistics::cpu_cycles_ += delta;

        // Accumulate durations to old thread.
        scheduler::current_thread_->statistics_.cpu_cycles_ += delta;

        // Remember the timestamp for the next context switch.
        scheduler::statistics::switch_timestamp_ = now;

#endif /* defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CPU_CYCLES) */

        // The very core of the scheduler, if not locked, re-link the
        // current thread and return the top priority thread.
        if (!locked ())
          {
            // Normally the old running thread must be re-linked to ready.
            scheduler::current_thread_->internal_relink_running_ ();

            // The top of the ready list gives the next thread to run.
            scheduler::current_thread_ =
                scheduler::ready_threads_list_.unlink_head ();
          }

        // ***** Pointer switched to new thread! *****

        // The new thread was marked as running in unlink_head(),
        // so in case the handler is re-entered immediately,
        // the relink_running() will simply reschedule it,
        // otherwise the thread will be lost.

#if defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CONTEXT_SWITCHES)

        // Increment global context switches.
        scheduler::statistics::context_switches_++;

        // Increment new thread context switches.
        scheduler::current_thread_->statistics_.context_switches_++;

#endif /* defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CONTEXT_SWITCHES) */

      }

#endif /* !defined(OS_USE_RTOS_PORT_SCHEDULER) */

      namespace statistics
      {
#if defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CONTEXT_SWITCHES)

        rtos::statistics::counter_t context_switches_;

#endif /* defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CONTEXT_SWITCHES) */

#if defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CPU_CYCLES)

        clock::timestamp_t switch_timestamp_;
        rtos::statistics::duration_t cpu_cycles_;

#endif /* defined(OS_INCLUDE_RTOS_STATISTICS_THREAD_CPU_CYCLES) */

      } /* namespace statistics */

    } /* namespace scheduler */

    namespace interrupts
    {
      /*
       * @var const state_t critical_section::state_
       * @details
       * The variable is constant, after being set by the constructor no
       * further changes are possible.
       *
       * The variable type usually is an unsigned integer where
       * the priorities register is saved.
       */

      /*
       * @var state_t lockable::state_
       * @details
       * The variable type usually is an unsigned integer where
       * the priorities register is saved.
       */

#if defined(OS_HAS_INTERRUPTS_STACK) || defined(__DOXYGEN__)

      class thread::stack*
      stack (void)
        {
          return &interrupts_stack;
        }

#endif /* defined(OS_HAS_INTERRUPTS_STACK) */

      ;
    // Avoid formatter bug.
    }
    /* namespace interrupts */

    // ========================================================================
    namespace internal
    {
      /*
       * @var const char* const object_named::name_
       * @details
       * To save space, the null terminated string passed to the
       * constructor is not copied locally. Instead, the pointer to
       * the string is copied, so the
       * caller must ensure that the pointer life cycle
       * is at least as long as the object life cycle. A constant
       * string (stored in flash) is preferred.
       */

      object_named::object_named ()
      {
        ;
      }

      object_named::object_named (const char* name) :
          name_ (name != nullptr ? name : "-")
      {
        ;
      }

    } /* namespace internal */

  // ==========================================================================
  } /* namespace rtos */
} /* namespace os */

int*
__errno (void);

int*
__errno (void)
{
  return os::rtos::this_thread::__errno ();
}