1/* $NetBSD: atomic_dec_32.S,v 1.1 2014/08/10 05:47:35 matt 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
34ENTRY_NP(_atomic_dec_32)
351:	ldxr	w3, [x0]		/* load old value (return value) */
36	sub	w3, w3, #1		/* calculate new value */
37	stxr	w2, w3, [x0]		/* try to store */
38	cbnz	w2, 1b			/*   succeed? no, try again? */
39	dmb	st
40	ret				/* return new value */
41END(_atomic_dec_32)
42
43ATOMIC_OP_ALIAS(atomic_dec_32,_atomic_dec_32)
44ATOMIC_OP_ALIAS(atomic_dec_uint,_atomic_dec_32)
45STRONG_ALIAS(_atomic_dec_uint,_atomic_dec_32)
46
47ENTRY_NP(_atomic_dec_32_nv)
48	mov	x4, x0			/* need r0 for return value */
491:	ldxr	w0, [x4]		/* load old value */
50	sub	w0, w0, #1		/* calculate new value (return value) */
51	stxr	w3, w0, [x4]		/* try to store */
52	cbnz	w3, 1b			/*   succeed? no, try again? */
53	dmb	st
54	ret				/* return new value */
55END(_atomic_dec_32_nv)
56
57ATOMIC_OP_ALIAS(atomic_dec_32_nv,_atomic_dec_32_nv)
58ATOMIC_OP_ALIAS(atomic_dec_uint_nv,_atomic_dec_32_nv)
59STRONG_ALIAS(_atomic_dec_uint_nv,_atomic_dec_32_nv)
60