OpenRTX/lib/miosix-kernel/miosix/kernel/scheduler/edf/edf_scheduler.h

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 *   Copyright (C) 2010, 2011 by Terraneo Federico                         *
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#ifndef EDF_SCHEDULER_H
#define	EDF_SCHEDULER_H

#include "config/miosix_settings.h"
#include "edf_scheduler_types.h"
#include "kernel/kernel.h"
#include <list>

#ifdef SCHED_TYPE_EDF

namespace miosix {

/**
 * \internal
 * EDF based scheduler.
 */
class EDFScheduler
{
public:
    /**
     * \internal
     * Add a new thread to the scheduler.
     * This is called when a thread is created.
     * \param thread a pointer to a valid thread instance.
     * The behaviour is undefined if a thread is added multiple timed to the
     * scheduler, or if thread is NULL.
     * \param priority the priority of the new thread.
     * Priority must be a positive value.
     * Note that the meaning of priority is scheduler specific.
     */
    static bool PKaddThread(Thread *thread, EDFSchedulerPriority priority);

    /**
     * \return true if thread exists, false if does not exist or has been
     * deleted. A joinable thread is considered existing until it has been
     * joined, even if it returns from its entry point (unless it is detached
     * and terminates).
     *
     * Can be called both with the kernel paused and with interrupts disabled.
     */
    static bool PKexists(Thread *thread);

    /**
     * \internal
     * Called when there is at least one dead thread to be removed from the
     * scheduler
     */
    static void PKremoveDeadThreads();

    /**
     * \internal
     * Set the priority of a thread.
     * Note that the meaning of priority is scheduler specific.
     * \param thread thread whose priority needs to be changed.
     * \param newPriority new thread priority.
     * Priority must be a positive value.
     */
    static void PKsetPriority(Thread *thread, EDFSchedulerPriority newPriority);

    /**
     * \internal
     * Get the priority of a thread.
     * Note that the meaning of priority is scheduler specific.
     * \param thread thread whose priority needs to be queried.
     * \return the priority of thread.
     */
    static EDFSchedulerPriority getPriority(Thread *thread)
    {
        return thread->schedData.deadline;
    }

    /**
     * Same as getPriority, but meant to be called with interrupts disabled.
     * \param thread thread whose priority needs to be queried.
     * \return the priority of thread.
     */
    static EDFSchedulerPriority IRQgetPriority(Thread *thread)
    {
        return thread->schedData.deadline;
    }

    /**
     * \internal
     * This is called before the kernel is started to by the kernel. The given
     * thread is the idle thread, to be run all the times where no other thread
     * can run.
     */
    static void IRQsetIdleThread(Thread *idleThread);

    /**
     * \internal
     * This member function is called by the kernel every time a thread changes
     * its running status. For example when a thread become sleeping, waiting,
     * deleted or if it exits the sleeping or waiting status
     */
    static void IRQwaitStatusHook() {}

    /**
     * This function is used to develop interrupt driven peripheral drivers.<br>
     * Can be used ONLY inside an IRQ (and not when interrupts are disabled) to
     * find next thread in READY status. If the kernel is paused, does nothing.
     * Can be used for example if an IRQ causes a higher priority thread to be
     * woken, to change context. Note that to use this function the IRQ must
     * use the macros to save/restore context defined in portability.h
     *
     * If the kernel is paused does nothing.
     * It's behaviour is to modify the global variable miosix::cur which always
     * points to the currently running thread.
     */
    static void IRQfindNextThread();

private:

    /**
     * Add a thread to the list of threads, keeping the list ordered by deadline
     * \param thread thread to add
     */
    static void add(Thread *thread);

    /**
     * Remove a thread to the list of threads.
     * \param thread thread to remove
     */
    static void remove(Thread *thread);

    static Thread *head;///<\internal Head of threads list, ordered by deadline
};

} //namespace miosix

#endif //SCHED_TYPE_EDF

#endif //EDF_SCHEDULER_H