atomic-x86.h revision d55f0adfb5ec4202ad5bd5d188e66c0f6a27b0aa 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_CUTILS_ATOMIC_X86_H
18#define ANDROID_CUTILS_ATOMIC_X86_H
19
20#include <stdint.h>
21
22extern inline void android_compiler_barrier(void)
23{
24    __asm__ __volatile__ ("" : : : "memory");
25}
26
27#if ANDROID_SMP == 0
28extern inline void android_memory_barrier(void)
29{
30    android_compiler_barrier();
31}
32#else
33extern inline void android_memory_barrier(void)
34{
35    __asm__ __volatile__ ("mfence" : : : "memory");
36}
37#endif
38
39extern inline int32_t android_atomic_acquire_load(volatile const int32_t *ptr)
40{
41    int32_t value = *ptr;
42    android_compiler_barrier();
43    return value;
44}
45
46extern inline int32_t android_atomic_release_load(volatile const int32_t *ptr)
47{
48    android_memory_barrier();
49    return *ptr;
50}
51
52extern inline void android_atomic_acquire_store(int32_t value,
53                                                volatile int32_t *ptr)
54{
55    *ptr = value;
56    android_memory_barrier();
57}
58
59extern inline void android_atomic_release_store(int32_t value,
60                                                volatile int32_t *ptr)
61{
62    android_compiler_barrier();
63    *ptr = value;
64}
65
66extern inline int android_atomic_cas(int32_t old_value, int32_t new_value,
67                                     volatile int32_t *ptr)
68{
69    int32_t prev;
70    __asm__ __volatile__ ("lock; cmpxchgl %1, %2"
71                          : "=a" (prev)
72                          : "q" (new_value), "m" (*ptr), "0" (old_value)
73                          : "memory");
74    return prev != old_value;
75}
76
77extern inline int android_atomic_acquire_cas(int32_t old_value,
78                                             int32_t new_value,
79                                             volatile int32_t *ptr)
80{
81    /* Loads are not reordered with other loads. */
82    return android_atomic_cas(old_value, new_value, ptr);
83}
84
85extern inline int android_atomic_release_cas(int32_t old_value,
86                                             int32_t new_value,
87                                             volatile int32_t *ptr)
88{
89    /* Stores are not reordered with other stores. */
90    return android_atomic_cas(old_value, new_value, ptr);
91}
92
93extern inline int32_t android_atomic_swap(int32_t new_value,
94                                          volatile int32_t *ptr)
95{
96    __asm__ __volatile__ ("xchgl %1, %0"
97                          : "=r" (new_value)
98                          : "m" (*ptr), "0" (new_value)
99                          : "memory");
100    /* new_value now holds the old value of *ptr */
101    return new_value;
102}
103
104extern inline int32_t android_atomic_add(int32_t increment,
105                                         volatile int32_t *ptr)
106{
107    __asm__ __volatile__ ("lock; xaddl %0, %1"
108                          : "+r" (increment), "+m" (*ptr)
109                          : : "memory");
110    /* increment now holds the old value of *ptr */
111    return increment;
112}
113
114extern inline int32_t android_atomic_inc(volatile int32_t *addr)
115{
116    return android_atomic_add(1, addr);
117}
118
119extern inline int32_t android_atomic_dec(volatile int32_t *addr)
120{
121    return android_atomic_add(-1, addr);
122}
123
124extern inline int32_t android_atomic_and(int32_t value,
125                                         volatile int32_t *ptr)
126{
127    int32_t prev, status;
128    do {
129        prev = *ptr;
130        status = android_atomic_cas(prev, prev & value, ptr);
131    } while (__builtin_expect(status != 0, 0));
132    return prev;
133}
134
135extern inline int32_t android_atomic_or(int32_t value, volatile int32_t *ptr)
136{
137    int32_t prev, status;
138    do {
139        prev = *ptr;
140        status = android_atomic_cas(prev, prev | value, ptr);
141    } while (__builtin_expect(status != 0, 0));
142    return prev;
143}
144
145#endif /* ANDROID_CUTILS_ATOMIC_X86_H */
146