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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
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