1 | /* |
2 | * Copyright (c) 2019 Apple Inc. All rights reserved. |
3 | * |
4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ |
5 | * |
6 | * This file contains Original Code and/or Modifications of Original Code |
7 | * as defined in and that are subject to the Apple Public Source License |
8 | * Version 2.0 (the 'License'). You may not use this file except in |
9 | * compliance with the License. The rights granted to you under the License |
10 | * may not be used to create, or enable the creation or redistribution of, |
11 | * unlawful or unlicensed copies of an Apple operating system, or to |
12 | * circumvent, violate, or enable the circumvention or violation of, any |
13 | * terms of an Apple operating system software license agreement. |
14 | * |
15 | * Please obtain a copy of the License at |
16 | * http://www.opensource.apple.com/apsl/ and read it before using this file. |
17 | * |
18 | * The Original Code and all software distributed under the License are |
19 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, |
22 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. |
23 | * Please see the License for the specific language governing rights and |
24 | * limitations under the License. |
25 | * |
26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ |
27 | */ |
28 | |
29 | #ifndef __OS_ATOMIC_H__ |
30 | #define __OS_ATOMIC_H__ |
31 | |
32 | /*! |
33 | * @file <os/atomic.h> |
34 | * |
35 | * @brief |
36 | * Small header that helps write code that works with both C11 and C++11, |
37 | * or pre-C11 type declarations. |
38 | * |
39 | * @discussion |
40 | * The macros below allow to write code like this, that can be put in a header |
41 | * and will work with both C11 and C++11: |
42 | * |
43 | * <code> |
44 | * struct old_type { |
45 | * int atomic_field; |
46 | * } old_variable; |
47 | * |
48 | * os_atomic_std(atomic_fetch_add_explicit)( |
49 | * os_cast_to_atomic_pointer(&old_variable), 1, |
50 | * os_atomic_std(memory_order_relaxed)); |
51 | * </code> |
52 | */ |
53 | |
54 | #include <os/base.h> |
55 | |
56 | #ifndef OS_ATOMIC_USES_CXX |
57 | #ifdef KERNEL |
58 | #define OS_ATOMIC_USES_CXX 0 |
59 | #elif defined(__cplusplus) && __cplusplus >= 201103L |
60 | #define OS_ATOMIC_USES_CXX 1 |
61 | #else |
62 | #define OS_ATOMIC_USES_CXX 0 |
63 | #endif |
64 | #endif |
65 | |
66 | #if OS_ATOMIC_USES_CXX |
67 | #include <atomic> |
68 | #define OS_ATOMIC_STD std:: |
69 | #define os_atomic_std(op) std::op |
70 | #define os_atomic(type) std::atomic<type> volatile |
71 | #define os_cast_to_atomic_pointer(p) os::cast_to_atomic_pointer(p) |
72 | #define os_atomic_basetypeof(p) decltype(os_cast_to_atomic_pointer(p)->load()) |
73 | #define os_cast_to_nonatomic_pointer(p) os::cast_to_nonatomic_pointer(p) |
74 | #else /* !OS_ATOMIC_USES_CXX */ |
75 | #include <stdatomic.h> |
76 | #define OS_ATOMIC_STD |
77 | #define os_atomic_std(op) op |
78 | #define os_atomic(type) type volatile _Atomic |
79 | #define os_cast_to_atomic_pointer(p) (__typeof__(*(p)) volatile _Atomic *)(uintptr_t)(p) |
80 | #define os_atomic_basetypeof(p) __typeof__(atomic_load(os_cast_to_atomic_pointer(p))) |
81 | #define os_cast_to_nonatomic_pointer(p) (os_atomic_basetypeof(p) *)(uintptr_t)(p) |
82 | #endif /* !OS_ATOMIC_USES_CXX */ |
83 | |
84 | /*! |
85 | * @group Internal implementation details |
86 | * |
87 | * @discussion The functions below are not intended to be used directly. |
88 | */ |
89 | |
90 | #if OS_ATOMIC_USES_CXX |
91 | #include <type_traits> |
92 | |
93 | namespace os { |
94 | template <class T> using remove_volatile_t = typename std::remove_volatile<T>::type; |
95 | |
96 | template <class T> |
97 | inline volatile std::atomic<remove_volatile_t<T> > * |
98 | cast_to_atomic_pointer(T *v) |
99 | { |
100 | return reinterpret_cast<volatile std::atomic<remove_volatile_t<T> > *>(v); |
101 | } |
102 | |
103 | template <class T> |
104 | inline volatile std::atomic<remove_volatile_t<T> > * |
105 | cast_to_atomic_pointer(std::atomic<T> *v) |
106 | { |
107 | return reinterpret_cast<volatile std::atomic<remove_volatile_t<T> > *>(v); |
108 | } |
109 | |
110 | template <class T> |
111 | inline volatile std::atomic<remove_volatile_t<T> > * |
112 | cast_to_atomic_pointer(volatile std::atomic<T> *v) |
113 | { |
114 | return reinterpret_cast<volatile std::atomic<remove_volatile_t<T> > *>(v); |
115 | } |
116 | |
117 | template <class T> |
118 | inline remove_volatile_t<T> * |
119 | cast_to_nonatomic_pointer(T *v) |
120 | { |
121 | return const_cast<remove_volatile_t<T> *>(v); |
122 | } |
123 | |
124 | template <class T> |
125 | inline remove_volatile_t<T> * |
126 | cast_to_nonatomic_pointer(std::atomic<T> *v) |
127 | { |
128 | return reinterpret_cast<remove_volatile_t<T> *>(v); |
129 | } |
130 | |
131 | template <class T> |
132 | inline remove_volatile_t<T> * |
133 | cast_to_nonatomic_pointer(volatile std::atomic<T> *v) |
134 | { |
135 | auto _v = const_cast<std::atomic<T> *>(v); |
136 | return reinterpret_cast<remove_volatile_t<T> *>(_v); |
137 | } |
138 | }; |
139 | #endif /* OS_ATOMIC_USES_CXX */ |
140 | |
141 | #endif /* __OS_ATOMIC_H__ */ |
142 | |