1/*
2 * Copyright 2013, winocm. <winocm@icloud.com>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without modification,
6 * are permitted provided that the following conditions are met:
7 *
8 *   Redistributions of source code must retain the above copyright notice, this
9 *   list of conditions and the following disclaimer.
10 *
11 *   Redistributions in binary form must reproduce the above copyright notice, this
12 *   list of conditions and the following disclaimer in the documentation and/or
13 *   other materials provided with the distribution.
14 *
15 *   If you are going to use this software in any form that does not involve
16 *   releasing the source to this project or improving it, let me know beforehand.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
22 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
25 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29/*
30 * ARM atomic hardware functions.
31 */
32
33#include <arm/arch.h>
34#include <arm/asm_help.h>
35
36/**
37 * hw_compare_and_store
38 *
39 * Take the value in the destination, compare it to the old value, if equal
40 * atomically write the new value to the address.
41 */
42.globl _hw_compare_and_store
43.globl _OSCompareAndSwap
44_hw_compare_and_store:
45_OSCompareAndSwap:
46    mov     x4, x0
47loop:
48    ldr     w3, [x2]
49    mov     x0, #0
50    cmp     w3, w4
51    b.ne    loop_exit
52    b.eq    loop_store
53    b       loop
54loop_exit:
55    ret     lr
56loop_store:
57    str     w1, [x2]
58    mov     x0, #1
59    ret     lr
60
61/* The others. */
62.align 6
63.globl _hw_atomic_sub
64.globl _hw_atomic_add
65.globl _hw_atomic_and_noret
66.globl _hw_atomic_or_noret
67_hw_atomic_sub:
68    mov     x2, x0
69try_sub:
70    ldr     x0, [x2]
71    sub     x0, x0, x1
72    str     x0, [x2]
73    ret     lr
74_hw_atomic_add:
75    mov     x2, x0
76try_add:
77    ldr     x0, [x2]
78    add     x0, x0, x1
79    str     x0, [x2]
80    ret     lr
81_hw_atomic_or_noret:
82    mov     x2, x0
83try_or:
84    ldr     x0, [x4]
85    orr     x0, x0, x1
86    str     x0, [x2]
87    ret     lr
88_hw_atomic_and_noret:
89    mov     x2, x0
90try_and:
91    ldr     x0, [x2]
92    and     x0, x0, x1
93    str     x0, [x2]
94    ret     lr
95
96