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/*

 *   FILE: semaphore.c

 * AUTHOR: kma@cse.ogi.edu

 *  DESCR: interrupt-safe i960 semaphore implementation; isn't ready for SMP

 */

#ident "$Id: semaphore.c,v 1.1.1.1 2001-09-10 07:43:56 simons Exp $"

#include <asm/semaphore.h>

#include <linux/sched.h>

extern int __down_common(struct semaphore* sem, int intrflag)

{

        long flags;

        int retval=0;

        save_flags(flags);

        cli();

        if (--sem->count < 0) {

                if (intrflag) {

                        interruptible_sleep_on(&sem->wait);

                        if (current->signal & ~current->blocked) {

                                retval = -1;

                        }

                }

                else

                        sleep_on(&sem->wait);

        }

        restore_flags(flags);

        return retval;

}

void down(struct semaphore * sem)

{

        __down_common(sem, 0);

}

/*

 * This version waits in interruptible state so that the waiting

 * process can be killed.  The down_failed_interruptible routine

 * returns negative for signalled and zero for semaphore acquired.

 */

extern int down_interruptible(struct semaphore * sem)

{

        return __down_common(sem, 1);

}

/*

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

 */

extern void get_buzz_lock(int *lock_ptr)

{

#ifdef __SMP__

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

#endif

}

extern void give_buzz_lock(int *lock_ptr)

{

#ifdef __SMP__

        *lock_ptr = 0 ;

#endif

}

/*

 * We wake people up only if the semaphore was negative (== somebody was

 * waiting on it).

 */

extern void up(struct semaphore * sem)

{

        long flags;

        save_flags(flags);

        cli();

        if (sem->count++ < 0)

                wake_up(&sem->wait);

        restore_flags(flags);

}