/*	$OpenBSD: lock.h,v 1.7 2013/05/21 20:05:30 tedu Exp $	*/
/*	$NetBSD: lock.h,v 1.1.2.2 2000/05/03 14:40:55 sommerfeld Exp $	*/

/*-
 * Copyright (c) 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Machine-dependent spin lock operations.
 */

#ifndef _MACHINE_LOCK_H_
#define	_MACHINE_LOCK_H_

/*
 * compiler barrier: prevent reordering of instructions.
 * XXX something similar will move to <sys/cdefs.h>
 * or thereabouts.
 * This prevents the compiler from reordering code around
 * this "instruction", acting as a sequence point for code generation.
 */

#define __lockbarrier() __asm __volatile("": : :"memory")
#define SPINLOCK_SPIN_HOOK __asm __volatile("pause": : :"memory");

#include <machine/atomic.h>

#define rw_cas(p, o, n) (x86_atomic_cas_ul(p, o, n) != o)

#endif /* _MACHINE_LOCK_H_ */