minix/common/lib/libc/arch/arm/atomic/atomic_swap_64.S

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/* $NetBSD: atomic_swap_64.S,v 1.2 2012/09/13 00:36:12 matt Exp $ */
/*-
* Copyright (c) 2012 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas.
*
* 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"
ENTRY_NP(_atomic_swap_64)
str r4, [sp, #-4]! /* save temporary */
mov r4, r0 /* return value will be in r0 */
#ifndef __ARM_EABI__
mov r3, r2 /* r2 will be overwriten by r1 */
mov r2, r1 /* and r1 will be overwritten by ldrexd */
#endif
1:
ldrexd r0, [r4] /* load old value */
strexd ip, r2, [r4] /* store new value */
cmpne ip, #0 /* succeed? */
bne 1b /* no, try again */
#ifdef _ARM_ARCH_7
dmb
#else
mcr p15, 0, ip, c7, c10, 5 /* data memory barrier */
#endif
ldr r4, [sp], #4 /* restore temporary */
RET
END(_atomic_swap_64)
ATOMIC_OP_ALIAS(atomic_swap_64,_atomic_swap_64)