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lock.h revision 1.1.2.2 
      1 /*	$NetBSD: lock.h,v 1.1.2.2 2000/05/03 14:40:55 sommerfeld 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 #include "opt_lockdebug.h"
     47 
     48 typedef	__volatile int		__cpu_simple_lock_t;
     49 
     50 #define	__SIMPLELOCK_LOCKED	1
     51 #define	__SIMPLELOCK_UNLOCKED	0
     52 
     53 #ifdef LOCKDEBUG
     54 
     55 extern void __cpu_simple_lock_init __P((__cpu_simple_lock_t *));
     56 extern void __cpu_simple_lock __P((__cpu_simple_lock_t *));
     57 extern int __cpu_simple_lock_try __P((__cpu_simple_lock_t *));
     58 extern void __cpu_simple_unlock __P((__cpu_simple_lock_t *));
     59 
     60 #else
     61 
     62 static __inline void __cpu_simple_lock_init __P((__cpu_simple_lock_t *))
     63 	__attribute__((__unused__));
     64 static __inline void __cpu_simple_lock __P((__cpu_simple_lock_t *))
     65 	__attribute__((__unused__));
     66 static __inline int __cpu_simple_lock_try __P((__cpu_simple_lock_t *))
     67 	__attribute__((__unused__));
     68 static __inline void __cpu_simple_unlock __P((__cpu_simple_lock_t *))
     69 	__attribute__((__unused__));
     70 
     71 static __inline void
     72 __cpu_simple_lock_init(__cpu_simple_lock_t *alp)
     73 {
     74 
     75 	*alp = __SIMPLELOCK_UNLOCKED;
     76 }
     77 
     78 static __inline void
     79 __cpu_simple_lock(__cpu_simple_lock_t *alp)
     80 {
     81 	int __val = __SIMPLELOCK_LOCKED;
     82 
     83 	do {
     84 		__asm __volatile("xchgl %0, %2"
     85 			: "=r" (__val)
     86 			: "0" (__val), "m" (*alp));
     87 	} while (__val != __SIMPLELOCK_UNLOCKED);
     88 }
     89 
     90 static __inline int
     91 __cpu_simple_lock_try(__cpu_simple_lock_t *alp)
     92 {
     93 	int __val = __SIMPLELOCK_LOCKED;
     94 
     95 	__asm __volatile("xchgl %0, %2"
     96 		: "=r" (__val)
     97 		: "0" (__val), "m" (*alp));
     98 
     99 	return ((__val == __SIMPLELOCK_UNLOCKED) ? 1 : 0);
    100 }
    101 
    102 void
    103 __cpu_simple_unlock(__cpu_simple_lock_t *alp)
    104 {
    105 
    106 	*alp = __SIMPLELOCK_UNLOCKED;
    107 }
    108 
    109 #endif /* !LOCKDEBUG */
    110 
    111 #endif /* _I386_LOCK_H_ */
    112