/*	$OpenBSD: lock.h,v 1.6 2011/03/23 16:54:37 pirofti Exp $	*/

/* public domain */

#ifndef	_MACHINE_LOCK_H_
#define	_MACHINE_LOCK_H_

#include <machine/atomic.h>
#include <machine/ctlreg.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__ void
__cpu_simple_lock(__cpu_simple_lock_t *l)
{
	__cpu_simple_lock_t old;

	do {
		old = __SIMPLELOCK_LOCKED;
		__asm__ __volatile__
		    ("ldstub [%0], %1" : "=r" (l), "=r" (old) : "0" (l));
		membar(LoadLoad | LoadStore);
	} while (old != __SIMPLELOCK_UNLOCKED);
}

static __inline__ int
__cpu_simple_lock_try(__cpu_simple_lock_t *l)
{
	__cpu_simple_lock_t old = __SIMPLELOCK_LOCKED;

	__asm__ __volatile__
	    ("ldstub [%0], %1" : "=r" (l), "=r" (old) : "0" (l));
	membar(LoadLoad | LoadStore);

	return (old == __SIMPLELOCK_UNLOCKED);
}

static __inline__ void
__cpu_simple_unlock(__cpu_simple_lock_t *l)
{
	membar(StoreStore | LoadStore);
	*l = __SIMPLELOCK_UNLOCKED;
}

#define	rw_cas(p, o, n)		(sparc64_casx(p, o, n) != o)

#endif	/* _MACHINE_LOCK_H_ */