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lock.h revision 1.5 
      1 /*	$NetBSD: lock.h,v 1.5 2001/04/30 01:17:31 lukem Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2000 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the NetBSD
     21  *	Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 /*
     40  * Machine-dependent spin lock operations.
     41  */
     42 
     43 #ifndef _I386_LOCK_H_
     44 #define	_I386_LOCK_H_
     45 
     46 typedef	__volatile int		__cpu_simple_lock_t;
     47 
     48 #define	__SIMPLELOCK_LOCKED	1
     49 #define	__SIMPLELOCK_UNLOCKED	0
     50 
     51 static __inline void __cpu_simple_lock_init __P((__cpu_simple_lock_t *))
     52 	__attribute__((__unused__));
     53 static __inline void __cpu_simple_lock __P((__cpu_simple_lock_t *))
     54 	__attribute__((__unused__));
     55 static __inline int __cpu_simple_lock_try __P((__cpu_simple_lock_t *))
     56 	__attribute__((__unused__));
     57 static __inline void __cpu_simple_unlock __P((__cpu_simple_lock_t *))
     58 	__attribute__((__unused__));
     59 
     60 static __inline void
     61 __cpu_simple_lock_init(__cpu_simple_lock_t *alp)
     62 {
     63 
     64 	*alp = __SIMPLELOCK_UNLOCKED;
     65 }
     66 
     67 static __inline void
     68 __cpu_simple_lock(__cpu_simple_lock_t *alp)
     69 {
     70 	int __val = __SIMPLELOCK_LOCKED;
     71 
     72 	do {
     73 		__asm __volatile("xchgl %0, %2"
     74 			: "=r" (__val)
     75 			: "0" (__val), "m" (*alp));
     76 	} while (__val != __SIMPLELOCK_UNLOCKED);
     77 }
     78 
     79 static __inline int
     80 __cpu_simple_lock_try(__cpu_simple_lock_t *alp)
     81 {
     82 	int __val = __SIMPLELOCK_LOCKED;
     83 
     84 	__asm __volatile("xchgl %0, %2"
     85 		: "=r" (__val)
     86 		: "0" (__val), "m" (*alp));
     87 
     88 	return ((__val == __SIMPLELOCK_UNLOCKED) ? 1 : 0);
     89 }
     90 
     91 static __inline void
     92 __cpu_simple_unlock(__cpu_simple_lock_t *alp)
     93 {
     94 
     95 	*alp = __SIMPLELOCK_UNLOCKED;
     96 }
     97 
     98 #endif /* _I386_LOCK_H_ */
     99