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atomic_cas_8.S revision 1.3 
      1 /* $NetBSD: atomic_cas_8.S,v 1.3 2020/10/07 07:31:47 skrll Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2014 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Matt Thomas of 3am Software Foundry.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "atomic_op_asm.h"
     33 
     34 ENTRY_NP(_atomic_cas_8)
     35 	mov	x4, x0			/* we need x0 for return value */
     36 1:	ldxrb	w0, [x4]		/* load old value */
     37 	cmp	w0, w1			/*   compare? */
     38 	b.ne	2f
     39 	stxrb	w3, w2, [x4]		/* store new value */
     40 	cbnz	w3, 3f			/*   succeed? nope, try again. */
     41 2:	ret				/* return. */
     42 3:	b	1b
     43 END(_atomic_cas_8)
     44 
     45 ATOMIC_OP_ALIAS(atomic_cas_8,_atomic_cas_8)
     46 STRONG_ALIAS(_atomic_cas_char,_atomic_cas_8)
     47 STRONG_ALIAS(_atomic_cas_uchar,_atomic_cas_8)
     48 STRONG_ALIAS(__sync_val_compare_and_swap_1,_atomic_cas_8)
     49