f8739dd5f9
Both are atomic, but the cmpxchg has memory ordering hints. We give this acquire semantics. NOTE: The unlock in libc_r is implemented by a "normal" assign statement. This is not correct on ia64 due to the memory ordering characteristics of the architecture. We need release semantics for an unlock.
50 lines
1.7 KiB
ArmAsm
50 lines
1.7 KiB
ArmAsm
/*
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* Copyright (c) 2002 Marcel Moolenaar
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#if defined(LIBC_RCS) && !defined(lint)
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.text
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.asciz "$FreeBSD$"
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#endif /* LIBC_RCS and not lint */
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#include <machine/asm.h>
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/*
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* Atomicly lock a location with an identifier provided the location
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* is not currently locked.
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*
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* long _atomic_lock(long *);
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*/
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ENTRY(_atomic_lock, 1)
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mov ar.ccv = r0
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add r14 = 1, r0
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nop 0
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;;
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cmpxchg8.acq r8 = [r32], r14, ar.ccv
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br.ret.sptk rp
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END(_atomic_lock)
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