uatomic: Fix header guard comment
[urcu.git] / include / urcu / system.h
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1// SPDX-FileCopyrightText: 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
2//
3// SPDX-License-Identifier: MIT
4
5#ifndef _URCU_SYSTEM_H
6#define _URCU_SYSTEM_H
7
8/*
9 * System definitions.
10 */
11
12#include <urcu/config.h>
13#include <urcu/compiler.h>
14#include <urcu/arch.h>
15
16#ifdef CONFIG_RCU_USE_ATOMIC_BUILTINS
17
18#define CMM_LOAD_SHARED(x) \
19 __atomic_load_n(cmm_cast_volatile(&(x)), __ATOMIC_RELAXED)
20
21#define _CMM_LOAD_SHARED(x) CMM_LOAD_SHARED(x)
22
23#define CMM_STORE_SHARED(x, v) \
24 __extension__ \
25 ({ \
26 __typeof__(v) _v = (v); \
27 __atomic_store_n(cmm_cast_volatile(&(x)), _v, \
28 __ATOMIC_RELAXED); \
29 _v; \
30 })
31
32#define _CMM_STORE_SHARED(x, v) CMM_STORE_SHARED(x, v)
33
34#else
35/*
36 * Identify a shared load. A cmm_smp_rmc() or cmm_smp_mc() should come
37 * before the load.
38 */
39#define _CMM_LOAD_SHARED(p) CMM_ACCESS_ONCE(p)
40
41/*
42 * Load a data from shared memory, doing a cache flush if required.
43 */
44#define CMM_LOAD_SHARED(p) \
45 __extension__ \
46 ({ \
47 cmm_smp_rmc(); \
48 _CMM_LOAD_SHARED(p); \
49 })
50
51/*
52 * Identify a shared store. A cmm_smp_wmc() or cmm_smp_mc() should
53 * follow the store.
54 */
55#define _CMM_STORE_SHARED(x, v) __extension__ ({ CMM_ACCESS_ONCE(x) = (v); })
56
57/*
58 * Store v into x, where x is located in shared memory. Performs the
59 * required cache flush after writing. Returns v.
60 */
61#define CMM_STORE_SHARED(x, v) \
62 __extension__ \
63 ({ \
64 __typeof__(x) _v = _CMM_STORE_SHARED(x, v); \
65 cmm_smp_wmc(); \
66 _v = _v; /* Work around clang "unused result" */ \
67 })
68
69#endif /* CONFIG_RCU_USE_ATOMIC_BUILTINS */
70
71#endif /* _URCU_SYSTEM_H */
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