1/* $NetBSD: atomic_cas_16.S,v 1.3 2021/07/28 07:32:20 skrll Exp $ */
2/*-
3 * Copyright (c) 2013 The NetBSD Foundation, Inc.
4 * All rights reserved.
5 *
6 * This code is derived from software contributed to The NetBSD Foundation
7 * by Matt Thomas <matt@3am-software.com>
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
20 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
22 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include "atomic_op_asm.h"
32
33#if defined(_ARM_ARCH_6)
34
35/*
36 * ARMv6 has load-exclusive/store-exclusive which works for both user
37 * and kernel.
38 */
39ENTRY_NP(_atomic_cas_16)
40          mov       ip, r0                        /* we need r0 for return value */
411:
42          ldrexh    r0, [ip]            /* load old value */
43          cmp       r0, r1                        /*   compare? */
44#ifdef __thumb__
45          bne       2f
46#else
47          RETc(ne)                      /*     return if different */
48#endif
49          strexh    r3, r2, [ip]                  /* store new value */
50          cmp       r3, #0                        /*   succeed? */
51          bne       1b                            /*     nope, try again. */
522:        RET                                     /* return. */
53END(_atomic_cas_16)
54
55ATOMIC_OP_ALIAS(atomic_cas_16,_atomic_cas_16)
56STRONG_ALIAS(_atomic_cas_short,_atomic_cas_16)
57STRONG_ALIAS(_atomic_cas_ushort,_atomic_cas_16)
58
59ENTRY_NP(__sync_val_compare_and_swap_2)
60          push      {r4, lr}
61          DMB
62          bl        _atomic_cas_16
63          DMB
64          pop       {r4, pc}
65END(__sync_val_compare_and_swap_2)
66
67#endif /* _ARM_ARCH_6 */
68