1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __TOOLS_ASM_GENERIC_ATOMIC_H
3 #define __TOOLS_ASM_GENERIC_ATOMIC_H
4 
5 #include <linux/compiler.h>
6 #include <linux/types.h>
7 
8 /*
9  * Atomic operations that C can't guarantee us.  Useful for
10  * resource counting etc..
11  *
12  * Excerpts obtained from the Linux kernel sources.
13  */
14 
15 #define ATOMIC_INIT(i)	{ (i) }
16 
17 /**
18  * atomic_read - read atomic variable
19  * @v: pointer of type atomic_t
20  *
21  * Atomically reads the value of @v.
22  */
23 static inline int atomic_read(const atomic_t *v)
24 {
25 	return READ_ONCE((v)->counter);
26 }
27 
28 /**
29  * atomic_set - set atomic variable
30  * @v: pointer of type atomic_t
31  * @i: required value
32  *
33  * Atomically sets the value of @v to @i.
34  */
35 static inline void atomic_set(atomic_t *v, int i)
36 {
37         v->counter = i;
38 }
39 
40 /**
41  * atomic_inc - increment atomic variable
42  * @v: pointer of type atomic_t
43  *
44  * Atomically increments @v by 1.
45  */
46 static inline void atomic_inc(atomic_t *v)
47 {
48 	__sync_add_and_fetch(&v->counter, 1);
49 }
50 
51 /**
52  * atomic_dec_and_test - decrement and test
53  * @v: pointer of type atomic_t
54  *
55  * Atomically decrements @v by 1 and
56  * returns true if the result is 0, or false for all other
57  * cases.
58  */
59 static inline int atomic_dec_and_test(atomic_t *v)
60 {
61 	return __sync_sub_and_fetch(&v->counter, 1) == 0;
62 }
63 
64 #define cmpxchg(ptr, oldval, newval) \
65 	__sync_val_compare_and_swap(ptr, oldval, newval)
66 
67 static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
68 {
69 	return cmpxchg(&(v)->counter, oldval, newval);
70 }
71 
72 #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
73