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Linux kernel mirror (for testing)
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1#ifndef __TOOLS_ASM_GENERIC_ATOMIC_H
2#define __TOOLS_ASM_GENERIC_ATOMIC_H
3
4#include <linux/compiler.h>
5#include <linux/types.h>
6
7/*
8 * Atomic operations that C can't guarantee us. Useful for
9 * resource counting etc..
10 *
11 * Excerpts obtained from the Linux kernel sources.
12 */
13
14#define ATOMIC_INIT(i) { (i) }
15
16/**
17 * atomic_read - read atomic variable
18 * @v: pointer of type atomic_t
19 *
20 * Atomically reads the value of @v.
21 */
22static inline int atomic_read(const atomic_t *v)
23{
24 return ACCESS_ONCE((v)->counter);
25}
26
27/**
28 * atomic_set - set atomic variable
29 * @v: pointer of type atomic_t
30 * @i: required value
31 *
32 * Atomically sets the value of @v to @i.
33 */
34static inline void atomic_set(atomic_t *v, int i)
35{
36 v->counter = i;
37}
38
39/**
40 * atomic_inc - increment atomic variable
41 * @v: pointer of type atomic_t
42 *
43 * Atomically increments @v by 1.
44 */
45static inline void atomic_inc(atomic_t *v)
46{
47 __sync_add_and_fetch(&v->counter, 1);
48}
49
50/**
51 * atomic_dec_and_test - decrement and test
52 * @v: pointer of type atomic_t
53 *
54 * Atomically decrements @v by 1 and
55 * returns true if the result is 0, or false for all other
56 * cases.
57 */
58static inline int atomic_dec_and_test(atomic_t *v)
59{
60 return __sync_sub_and_fetch(&v->counter, 1) == 0;
61}
62
63#define cmpxchg(ptr, oldval, newval) \
64 __sync_val_compare_and_swap(ptr, oldval, newval)
65
66static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
67{
68 return cmpxchg(&(v)->counter, oldval, newval);
69}
70
71#endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */