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#ifndef CYGONCE_KERNEL_SCHED_HXX

#define CYGONCE_KERNEL_SCHED_HXX

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

//

//      sched.hxx

//

//      Scheduler class declaration(s)

//

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

//####ECOSGPLCOPYRIGHTBEGIN####

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

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//####ECOSGPLCOPYRIGHTEND####

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

//#####DESCRIPTIONBEGIN####

//

// Author(s):   nickg

// Contributors:        nickg

// Date:        1997-09-09

// Purpose:     Define Scheduler class interfaces

// Description: These class definitions supply the internal API

//              used to scheduler threads.

// Usage:       #include 

//

//####DESCRIPTIONEND####

//

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

#include 

#include          // assertion macros

#include           // SMP support

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

// Miscellaneous types

#ifdef CYGSEM_KERNEL_SCHED_ASR_SUPPORT

typedef void Cyg_ASR( CYG_ADDRWORD data );      // ASR type signature

#endif

__externC void cyg_scheduler_set_need_reschedule();

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

// Scheduler base class. This defines stuff that is needed by the

// specific scheduler implementation. Each scheduler comprises three

// classes: Cyg_Scheduler_Base, Cyg_Scheduler_Implementation which

// inherits from it and Cyg_Scheduler which inherits from _it_ in turn.

class Cyg_Scheduler_Base

     : public Cyg_Scheduler_SchedLock

{

    friend class Cyg_HardwareThread;

    friend class Cyg_SchedThread;

protected:

    // The following variables are implicit in the API, but are

    // not publically visible.

    // Current running thread

    static Cyg_Thread * volatile current_thread[CYGNUM_KERNEL_CPU_MAX]

                                                CYGBLD_ANNOTATE_VARIABLE_SCHED;

    // Set when reschedule needed

    static volatile cyg_bool     need_reschedule[CYGNUM_KERNEL_CPU_MAX]

                                                 CYGBLD_ANNOTATE_VARIABLE_SCHED;

    // Count of number of thread switches

    static volatile cyg_ucount32 thread_switches[CYGNUM_KERNEL_CPU_MAX]

                                                 CYGBLD_ANNOTATE_VARIABLE_SCHED;

public:

    // return a pointer to the current thread

    static Cyg_Thread *get_current_thread();

    // Set current thread pointer

    static void set_current_thread(Cyg_Thread *thread);

    static void set_current_thread(Cyg_Thread *thread, HAL_SMP_CPU_TYPE cpu);

    // Set need_reschedule flag

    static void set_need_reschedule();

    static void set_need_reschedule(Cyg_Thread *thread);

    // Get need_reschedule flag

    static cyg_bool get_need_reschedule();

    // Return current value of lock

    static cyg_ucount32 get_sched_lock();

    // Clear need_reschedule flag

    static void clear_need_reschedule();

    // Return current number of thread switches

    static cyg_ucount32 get_thread_switches();

};

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

// Include the scheduler implementation header

#include CYGPRI_KERNEL_SCHED_IMPL_HXX

// Do some checking that we have a consistent universe.

#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL

# ifndef CYGIMP_THREAD_PRIORITY

#  error Priority inversion protocols will not work without priorities!!!

# endif

#endif

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

// Scheduler class. This is the public scheduler interface seen by the

// rest of the kernel.

class Cyg_Scheduler

    : public Cyg_Scheduler_Implementation

{

    friend class Cyg_Thread;

    // This function is the actual implementation of the unlock

    // function.  The unlock() later is an inline shell that deals

    // with the common case.

    static void             unlock_inner(cyg_uint32 new_lock = 0);

public:

    CYGDBG_DEFINE_CHECK_THIS

    // The following API functions are common to all scheduler

    // implementations.

    // claim the preemption lock

    static void             lock();

    // release the preemption lock and possibly reschedule

    static void             unlock();

    // release and reclaim the lock atomically, keeping the old

    // value on restart

    static void             reschedule();

    // decrement the lock but also look for a reschedule opportunity

    static void             unlock_reschedule();

    // release the preemption lock without rescheduling

    static void             unlock_simple();

    // Start execution of the scheduler

    static void start() CYGBLD_ATTRIB_NORET;

    // Start execution of the scheduler on the current CPU

    static void start_cpu() CYGBLD_ATTRIB_NORET;

    // The only  scheduler instance should be this one...

    static Cyg_Scheduler scheduler CYGBLD_ANNOTATE_VARIABLE_SCHED;

};

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

// This class encapsulates the scheduling abstractions in a thread.

// Cyg_SchedThread is included as a base class of Cyg_Thread. The actual

// implementation of the abstractions is in Cyg_SchedThread_Implementation

// so this class has little to do.

class Cyg_SchedThread

    : public Cyg_SchedThread_Implementation

{

    friend class Cyg_ThreadQueue_Implementation;

    friend class Cyg_Scheduler_Implementation;

    friend class Cyg_Scheduler;

    Cyg_ThreadQueue     *queue;

public:

    Cyg_SchedThread(Cyg_Thread *thread, CYG_ADDRWORD sched_info);

    // Return current queue pointer

    Cyg_ThreadQueue     *get_current_queue();

    // Remove this thread from current queue

    void remove();

#ifdef CYGSEM_KERNEL_SCHED_ASR_SUPPORT

    // ASR support.

    // An ASR is an Asynchronous Service Routine. When set pending it

    // is called when the thread exits the scheduler. ASRs are mainly

    // used by compatibility subsystems, such as POSIX, to implement

    // such things as thread cancellation and signal delivery.

private:

    volatile cyg_ucount32       asr_inhibit;    // If > 0, blocks calls to ASRs

    volatile cyg_bool           asr_pending;    // If true, this thread's ASR should be called.

#ifdef CYGSEM_KERNEL_SCHED_ASR_GLOBAL

    static

#endif

    Cyg_ASR             *asr;            // ASR function

#ifdef CYGSEM_KERNEL_SCHED_ASR_DATA_GLOBAL

    static

#endif

    CYG_ADDRWORD        asr_data;       // ASR data pointer

    // Default ASR function

    static void         asr_default(CYG_ADDRWORD data);

public:

    // Public interface to ASR mechanism

    // Set, clear and get inhibit flag.

    inline void set_asr_inhibit() { asr_inhibit++; }

    inline void clear_asr_inhibit() { asr_inhibit--; }

    inline cyg_ucount32 get_asr_inhibit() { return asr_inhibit; }

    // Set and get pending flag. The flag is only cleared when the

    // ASR is called.

    inline void set_asr_pending() { asr_pending = true; }

    inline cyg_bool get_asr_pending() { return asr_pending; }

    // Set a new ASR, returning the old one.

    void set_asr( Cyg_ASR  *new_asr, CYG_ADDRWORD  new_data,

                  Cyg_ASR **old_asr, CYG_ADDRWORD *old_data);

    // Clear the ASR function back to the default.

    void clear_asr();

#else

public:

    // Even when we do not have ASRs enabled, we keep these functions

    // available. This avoids excessive ifdefs in the rest of the

    // kernel code.

    inline void set_asr_inhibit() { }

    inline void clear_asr_inhibit() { }

#endif

#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL

private:

    // For all priority inversion protocols we need to keep track of how

    // many mutexes we have locked, including one which we are waiting to

    // lock, because we can inherit priority while sleeping just prior to

    // wakeup.

    cyg_count32         mutex_count;

protected:

    // These are implementation functions that are common to all protocols.

    // Inherit the given priority. If thread is non-NULL the priority is

    // being inherited from it, otherwise it has come from the mutex.

    void set_inherited_priority( cyg_priority pri, Cyg_Thread *thread = 0 );

    // Relay the priority of the ex-owner thread or from the queue if it

    // has a higher priority than ours.

    void relay_inherited_priority( Cyg_Thread *ex_owner, Cyg_ThreadQueue *pqueue);

    // Lose priority inheritance

    void clear_inherited_priority();

public:

    // Count and uncount the number of mutexes held by

    // this thread.

    void count_mutex() { mutex_count++; };

    void uncount_mutex() { mutex_count--; };

#if defined(CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_SIMPLE)

protected:

    // The simple priority inversion protocols simply needs

    // somewhere to store the base priority of the current thread.

    cyg_priority        original_priority;      // our original priority

    cyg_bool            priority_inherited;     // have we inherited?

#endif

#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_INHERIT

public:

    // Inherit the priority of the provided thread if it

    // has higher priority than this.

    void inherit_priority( Cyg_Thread *thread);

    // Relay the priority of the ex-owner thread or from the queue if it

    // has a higher priority than ours.

    void relay_priority( Cyg_Thread *ex_owner, Cyg_ThreadQueue *pqueue);

    // Lose priority inheritance

    void disinherit_priority();

#endif

#ifdef CYGSEM_KERNEL_SYNCH_MUTEX_PRIORITY_INVERSION_PROTOCOL_CEILING

public:

    // Set the priority of this thread to the given ceiling.

    void set_priority_ceiling( cyg_priority pri );

    // Clear the ceiling, if necessary.

    void clear_priority_ceiling();

#endif

#endif

};

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

// Simple inline accessor functions

inline Cyg_Thread *Cyg_Scheduler_Base::get_current_thread()

{

    return current_thread[CYG_KERNEL_CPU_THIS()];

}

inline void Cyg_Scheduler_Base::set_current_thread(Cyg_Thread *thread )

{

    current_thread[CYG_KERNEL_CPU_THIS()] = thread;

}

inline void Cyg_Scheduler_Base::set_current_thread(Cyg_Thread *thread,

                                                   HAL_SMP_CPU_TYPE cpu)

{

    current_thread[cpu] = thread;

}

inline cyg_bool Cyg_Scheduler_Base::get_need_reschedule()

{

    return need_reschedule[CYG_KERNEL_CPU_THIS()];

}

inline void Cyg_Scheduler_Base::set_need_reschedule()

{

    need_reschedule[CYG_KERNEL_CPU_THIS()] = true;

}

inline void Cyg_Scheduler_Base::set_need_reschedule(Cyg_Thread *thread)

{

    need_reschedule[CYG_KERNEL_CPU_THIS()] = true;

}

inline void Cyg_Scheduler_Base::clear_need_reschedule()

{

    need_reschedule[CYG_KERNEL_CPU_THIS()] = false;

}

inline cyg_ucount32 Cyg_Scheduler_Base::get_sched_lock()

{

    return Cyg_Scheduler_SchedLock::get_sched_lock();

}

// Return current number of thread switches

inline cyg_ucount32 Cyg_Scheduler_Base::get_thread_switches()

{

    return thread_switches[CYG_KERNEL_CPU_THIS()];

}

// Return current queue pointer

inline Cyg_ThreadQueue *Cyg_SchedThread::get_current_queue()

{

    return queue;

}

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

#endif // ifndef __SCHED_HXX__

// EOF sched.hxx