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  */
22 static 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  */
34 static 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  */
45 static 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  */
58 static inline int atomic_dec_and_test(atomic_t *v)
59 {
60 	return __sync_sub_and_fetch(&v->counter, 1) == 0;
61 }
62 
63 #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
64