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#ifndef _ALPHA_SEMAPHORE_H

#define _ALPHA_SEMAPHORE_H

/*

 * SMP- and interrupt-safe semaphores..

 *

 * (C) Copyright 1996 Linus Torvalds

 */

#include <asm/atomic.h>

#include <asm/system.h>

struct semaphore {

        atomic_t count;

        atomic_t waking;

        int lock;                       /* to make waking testing atomic */

        struct wait_queue * wait;

};

#define MUTEX ((struct semaphore) { 1, 0, 0, NULL })

#define MUTEX_LOCKED ((struct semaphore) { 0, 0, 0, NULL })

extern void __down(struct semaphore * sem);

extern int  __down_interruptible(struct semaphore * sem);

extern void __up(struct semaphore * sem);

/*

 * This isn't quite as clever as the x86 side, but the gp register

 * makes things a bit more complicated on the alpha..

 */

extern inline void down(struct semaphore * sem)

{

        if (atomic_dec_return(&sem->count) < 0)

                __down(sem);

}

/*

 * Primitives to spin on a lock.  Needed only for SMP version.

 */

extern inline void get_buzz_lock(int *lock_ptr)

{

#ifdef __SMP__

        while (xchg(lock_ptr,1) != 0) ;

#endif

} /* get_buzz_lock */

extern inline void give_buzz_lock(int *lock_ptr)

{

#ifdef __SMP__

        *lock_ptr = 0 ;

#endif

} /* give_buzz_lock */

extern inline int down_interruptible(struct semaphore * sem)

{

        int ret = 0;

        if (atomic_dec_return(&sem->count) < 0)

                ret = __down_interruptible(sem);

        return ret;

}

extern inline void up(struct semaphore * sem)

{

        if (atomic_inc_return(&sem->count) <= 0)

                __up(sem);

}

#endif