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/* $NetBSD: atomic_cas_8.S,v 1.7 2014/03/04 16:15:28 matt Exp $ */
/*-
* Copyright (c) 2013 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas <matt@3am-software.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "atomic_op_asm.h"
#if defined(_ARM_ARCH_6)
/*
* ARMv6 has load-exclusive/store-exclusive which works for both user
* and kernel.
*/
ENTRY_NP(_atomic_cas_8)
mov ip, r0 /* we need r0 for return value */
1:
ldrexb r0, [ip] /* load old value */
cmp r0, r1 /* compare? */
#ifdef __thumb__
bne 2f
#else
RETc(ne) /* return if different */
#endif
strexb r3, r2, [ip] /* store new value */
cmp r3, #0 /* succeed? */
bne 1b /* nope, try again. */
#ifdef _ARM_ARCH_7
dsb /* data synchronization barrier */
#else
mcr p15, 0, r3, c7, c10, 4 /* data synchronization barrier */
#endif
2: RET /* return. */
END(_atomic_cas_8)
ATOMIC_OP_ALIAS(atomic_cas_8,_atomic_cas_8)
STRONG_ALIAS(_atomic_cas_char,_atomic_cas_8)
STRONG_ALIAS(_atomic_cas_uchar,_atomic_cas_8)
CRT_ALIAS(__sync_val_compare_and_swap_1,_atomic_cas_8)
#endif /* _ARM_ARCH_6 */
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