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lock.h revision 1.10 
      1 /* 	$NetBSD: lock.h,v 1.10 2006/09/22 08:31:34 skrll Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1998, 1999, 2000, 2001 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 of the Numerical Aerospace Simulation Facility,
      9  * NASA Ames Research Center, and Matthew Fredette.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  * 3. All advertising materials mentioning features or use of this software
     20  *    must display the following acknowledgement:
     21  *	This product includes software developed by the NetBSD
     22  *	Foundation, Inc. and its contributors.
     23  * 4. Neither the name of The NetBSD Foundation nor the names of its
     24  *    contributors may be used to endorse or promote products derived
     25  *    from this software without specific prior written permission.
     26  *
     27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     37  * POSSIBILITY OF SUCH DAMAGE.
     38  */
     39 
     40 /*
     41  * Machine-dependent spin lock operations.
     42  */
     43 
     44 #ifndef _HPPA_LOCK_H_
     45 #define	_HPPA_LOCK_H_
     46 
     47 static __inline int
     48 __ldcw(__cpu_simple_lock_t *__ptr)
     49 {
     50 	int __val;
     51 
     52 	__asm volatile("ldcw 0(%1), %0"
     53 	    : "=r" (__val) : "r" (__ptr)
     54 	    : "memory");
     55 
     56 	return __val;
     57 }
     58 
     59 static __inline void
     60 __sync(void)
     61 {
     62 
     63 	__asm volatile("sync\n"
     64 		: /* no outputs */
     65 		: /* no inputs */
     66 		: "memory");
     67 }
     68 
     69 static __inline void
     70 __cpu_simple_lock_init(__cpu_simple_lock_t *alp)
     71 {
     72 
     73 	*alp = __SIMPLELOCK_UNLOCKED;
     74 	__sync();
     75 }
     76 
     77 static __inline void
     78 __cpu_simple_lock(__cpu_simple_lock_t *alp)
     79 {
     80 
     81 	/*
     82 	 * Note, if we detect that the lock is held when
     83 	 * we do the initial load-clear-word, we spin using
     84 	 * a non-locked load to save the coherency logic
     85 	 * some work.
     86 	 */
     87 
     88 	while (__ldcw(alp) == __SIMPLELOCK_LOCKED)
     89 		while (*alp == __SIMPLELOCK_LOCKED)
     90 			;
     91 }
     92 
     93 static __inline int
     94 __cpu_simple_lock_try(__cpu_simple_lock_t *alp)
     95 {
     96 
     97 	return (__ldcw(alp) != __SIMPLELOCK_LOCKED);
     98 }
     99 
    100 static __inline void
    101 __cpu_simple_unlock(__cpu_simple_lock_t *alp)
    102 {
    103 	__sync();
    104 	*alp = __SIMPLELOCK_UNLOCKED;
    105 }
    106 
    107 #endif /* _HPPA_LOCK_H_ */
    108