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/* $OpenBSD: lock.h,v 1.5 2011/07/02 22:19:16 guenther Exp $ */
/* public domain */
#ifndef _MACHINE_LOCK_H_
#define _MACHINE_LOCK_H_
#include <machine/atomic.h>
typedef volatile u_int8_t __cpu_simple_lock_t;
#define __SIMPLELOCK_LOCKED 0xff
#define __SIMPLELOCK_UNLOCKED 0x00
static __inline__ void
__cpu_simple_lock_init(__cpu_simple_lock_t *l)
{
*l = __SIMPLELOCK_UNLOCKED;
}
static __inline__ u_int8_t
__cpu_ldstub(__cpu_simple_lock_t *l)
{
u_int8_t old;
__asm__ __volatile__
("ldstub [%1], %0" : "=&r" (old) : "r" (l) : "memory");
return old;
}
static __inline__ void
__cpu_simple_lock(__cpu_simple_lock_t *l)
{
while (__cpu_ldstub(l) != __SIMPLELOCK_UNLOCKED)
while (*l != __SIMPLELOCK_UNLOCKED)
;
}
static __inline__ int
__cpu_simple_lock_try(__cpu_simple_lock_t *l)
{
if (__cpu_ldstub(l) != __SIMPLELOCK_UNLOCKED)
return (0);
return (1);
}
static __inline__ void
__cpu_simple_unlock(__cpu_simple_lock_t *l)
{
*l = __SIMPLELOCK_UNLOCKED;
}
#endif /* _MACHINE_LOCK_H_ */
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