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1 /* $NetBSD: lock.h,v 1.7 2005/12/28 19:09:29 perry Exp $ */
4 * Copyright (c) 2000, 2001 The NetBSD Foundation, Inc.
7 * This code is derived from software contributed to The NetBSD Foundation
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11 * modification, are permitted provided that the following conditions
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14 * notice, this list of conditions and the following disclaimer.
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16 * notice, this list of conditions and the following disclaimer in the
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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.
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
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36 * POSSIBILITY OF SUCH DAMAGE.
40 * Machine-dependent spin lock operations.
42 * NOTE: The SWP insn used here is available only on ARM architecture
43 * version 3 and later (as well as 2a). What we are going to do is
44 * expect that the kernel will trap and emulate the insn. That will
45 * be slow, but give us the atomicity that we need.
52 __swp(int __val
, volatile int *__ptr
)
55 __asm
volatile("swp %0, %1, [%2]"
56 : "=r" (__val
) : "r" (__val
), "r" (__ptr
) : "memory");
60 static __inline
void __attribute__((__unused__
))
61 __cpu_simple_lock_init(__cpu_simple_lock_t
*alp
)
64 *alp
= __SIMPLELOCK_UNLOCKED
;
67 static __inline
void __attribute__((__unused__
))
68 __cpu_simple_lock(__cpu_simple_lock_t
*alp
)
71 while (__swp(__SIMPLELOCK_LOCKED
, alp
) != __SIMPLELOCK_UNLOCKED
)
75 static __inline
int __attribute__((__unused__
))
76 __cpu_simple_lock_try(__cpu_simple_lock_t
*alp
)
79 return (__swp(__SIMPLELOCK_LOCKED
, alp
) == __SIMPLELOCK_UNLOCKED
);
82 static __inline
void __attribute__((__unused__
))
83 __cpu_simple_unlock(__cpu_simple_lock_t
*alp
)
86 *alp
= __SIMPLELOCK_UNLOCKED
;
89 #endif /* _ARM_LOCK_H_ */