os-condvar.cpp

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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.
 */
 
#if defined(OS_USE_OS_APP_CONFIG_H)
#include <cmsis-plus/os-app-config.h>
#endif
 
#include <cmsis-plus/rtos/os.h>
 
// ----------------------------------------------------------------------------
 
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wc++98-compat"
#endif
 
// ----------------------------------------------------------------------------
 
namespace os
{
  namespace rtos
  {
    // ------------------------------------------------------------------------
 
    const condition_variable::attributes condition_variable::initializer;
 
    // ------------------------------------------------------------------------
 
    // ========================================================================
    condition_variable::condition_variable (const attributes& attr)
        : condition_variable{ nullptr, attr }
    {
    }
 
    condition_variable::condition_variable (const char* name,
                                            const attributes& attr
                                            __attribute__ ((unused)))
        : object_named_system{ name }
    {
#if defined(OS_TRACE_RTOS_CONDVAR)
      trace::printf ("%s() @%p %s\n", __func__, this, this->name ());
#endif
 
      // Don't call this from interrupt handlers.
      os_assert_throw (!interrupts::in_handler_mode (), EPERM);
    }
 
    condition_variable::~condition_variable ()
    {
#if defined(OS_TRACE_RTOS_CONDVAR)
      trace::printf ("%s() @%p %s\n", __func__, this, name ());
#endif
 
      // There must be no threads waiting for this condition.
      assert (list_.empty ());
    }
 
    result_t
    condition_variable::signal ()
    {
#if defined(OS_TRACE_RTOS_CONDVAR)
      trace::printf ("%s() @%p %s\n", __func__, this, name ());
#endif
 
      // Don't call this from interrupt handlers.
      os_assert_err (!interrupts::in_handler_mode (), EPERM);
 
      list_.resume_one ();
 
      return result::ok;
    }
 
    result_t
    condition_variable::broadcast ()
    {
#if defined(OS_TRACE_RTOS_CONDVAR)
      trace::printf ("%s() @%p %s\n", __func__, this, name ());
#endif
 
      // Don't call this from interrupt handlers.
      os_assert_err (!interrupts::in_handler_mode (), EPERM);
 
      // Wake-up all threads, if any.
      // Need not be inside the critical section,
      // the list is protected by inner `resume_one()`.
      list_.resume_all ();
 
      return result::ok;
    }
 
    result_t
    condition_variable::wait (mutex& mutex)
    {
#if defined(OS_TRACE_RTOS_CONDVAR)
      trace::printf ("%s() @%p %s\n", __func__, this, name ());
#endif
 
      // Don't call this from interrupt handlers.
      os_assert_err (!interrupts::in_handler_mode (), EPERM);
      // Don't call this from critical regions.
      os_assert_err (!scheduler::locked (), EPERM);
 
      thread& crt_thread = this_thread::thread ();
 
      // Prepare a list node pointing to the current thread.
      // Do not worry for being on stack, it is temporarily linked to the
      // list and guaranteed to be removed before this function returns.
      internal::waiting_thread_node node{ crt_thread };
 
      // TODO: validate
 
      result_t res;
      res = mutex.unlock ();
 
      if (res != result::ok)
        {
          return res;
        }
 
      {
        // Add this thread to the condition variable waiting list.
        list_.link (node);
        node.thread_->waiting_node_ = &node;
 
        res = mutex.lock ();
 
        // Remove the thread from the node waiting list,
        // if not already removed.
        node.thread_->waiting_node_ = nullptr;
        node.unlink ();
      }
 
      return res;
    }
 
    result_t
    condition_variable::timed_wait (mutex& mutex, clock::duration_t timeout)
    {
#if defined(OS_TRACE_RTOS_CONDVAR)
 
#pragma GCC diagnostic push
#if defined(__clang__)
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wuseless-cast"
#endif
      trace::printf ("%s(%u) @%p %s\n", __func__,
                     static_cast<unsigned int> (timeout), this, name ());
#pragma GCC diagnostic pop
 
#endif // defined(OS_TRACE_RTOS_CONDVAR)
 
      // Don't call this from interrupt handlers.
      os_assert_err (!interrupts::in_handler_mode (), EPERM);
      // Don't call this from critical regions.
      os_assert_err (!scheduler::locked (), EPERM);
 
      thread& crt_thread = this_thread::thread ();
 
      // Prepare a list node pointing to the current thread.
      // Do not worry for being on stack, it is temporarily linked to the
      // list and guaranteed to be removed before this function returns.
      internal::waiting_thread_node node{ crt_thread };
 
      // TODO: validate
 
      result_t res;
      res = mutex.unlock ();
 
      if (res != result::ok)
        {
          return res;
        }
 
      {
        // Add this thread to the condition variable waiting list.
        list_.link (node);
        node.thread_->waiting_node_ = &node;
 
        res = mutex.timed_lock (timeout);
 
        // Remove the thread from the node waiting list,
        // if not already removed.
        node.thread_->waiting_node_ = nullptr;
        node.unlink ();
      }
 
      return res;
    }
 
    // ------------------------------------------------------------------------
 
  } /* namespace rtos */
} /* namespace os */
 
// ----------------------------------------------------------------------------