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 */
atomic_read(const atomic_t * v)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 */
atomic_set(atomic_t * v,int i)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 */
atomic_inc(atomic_t * v)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 */
atomic_dec_and_test(atomic_t * v)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
atomic_cmpxchg(atomic_t * v,int oldval,int newval)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