1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0 */
2*4882a593Smuzhiyun #ifndef __TOOLS_ASM_GENERIC_ATOMIC_H
3*4882a593Smuzhiyun #define __TOOLS_ASM_GENERIC_ATOMIC_H
4*4882a593Smuzhiyun
5*4882a593Smuzhiyun #include <linux/compiler.h>
6*4882a593Smuzhiyun #include <linux/types.h>
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun /*
9*4882a593Smuzhiyun * Atomic operations that C can't guarantee us. Useful for
10*4882a593Smuzhiyun * resource counting etc..
11*4882a593Smuzhiyun *
12*4882a593Smuzhiyun * Excerpts obtained from the Linux kernel sources.
13*4882a593Smuzhiyun */
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #define ATOMIC_INIT(i) { (i) }
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun /**
18*4882a593Smuzhiyun * atomic_read - read atomic variable
19*4882a593Smuzhiyun * @v: pointer of type atomic_t
20*4882a593Smuzhiyun *
21*4882a593Smuzhiyun * Atomically reads the value of @v.
22*4882a593Smuzhiyun */
atomic_read(const atomic_t * v)23*4882a593Smuzhiyun static inline int atomic_read(const atomic_t *v)
24*4882a593Smuzhiyun {
25*4882a593Smuzhiyun return READ_ONCE((v)->counter);
26*4882a593Smuzhiyun }
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun /**
29*4882a593Smuzhiyun * atomic_set - set atomic variable
30*4882a593Smuzhiyun * @v: pointer of type atomic_t
31*4882a593Smuzhiyun * @i: required value
32*4882a593Smuzhiyun *
33*4882a593Smuzhiyun * Atomically sets the value of @v to @i.
34*4882a593Smuzhiyun */
atomic_set(atomic_t * v,int i)35*4882a593Smuzhiyun static inline void atomic_set(atomic_t *v, int i)
36*4882a593Smuzhiyun {
37*4882a593Smuzhiyun v->counter = i;
38*4882a593Smuzhiyun }
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun /**
41*4882a593Smuzhiyun * atomic_inc - increment atomic variable
42*4882a593Smuzhiyun * @v: pointer of type atomic_t
43*4882a593Smuzhiyun *
44*4882a593Smuzhiyun * Atomically increments @v by 1.
45*4882a593Smuzhiyun */
atomic_inc(atomic_t * v)46*4882a593Smuzhiyun static inline void atomic_inc(atomic_t *v)
47*4882a593Smuzhiyun {
48*4882a593Smuzhiyun __sync_add_and_fetch(&v->counter, 1);
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun /**
52*4882a593Smuzhiyun * atomic_dec_and_test - decrement and test
53*4882a593Smuzhiyun * @v: pointer of type atomic_t
54*4882a593Smuzhiyun *
55*4882a593Smuzhiyun * Atomically decrements @v by 1 and
56*4882a593Smuzhiyun * returns true if the result is 0, or false for all other
57*4882a593Smuzhiyun * cases.
58*4882a593Smuzhiyun */
atomic_dec_and_test(atomic_t * v)59*4882a593Smuzhiyun static inline int atomic_dec_and_test(atomic_t *v)
60*4882a593Smuzhiyun {
61*4882a593Smuzhiyun return __sync_sub_and_fetch(&v->counter, 1) == 0;
62*4882a593Smuzhiyun }
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun #define cmpxchg(ptr, oldval, newval) \
65*4882a593Smuzhiyun __sync_val_compare_and_swap(ptr, oldval, newval)
66*4882a593Smuzhiyun
atomic_cmpxchg(atomic_t * v,int oldval,int newval)67*4882a593Smuzhiyun static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
68*4882a593Smuzhiyun {
69*4882a593Smuzhiyun return cmpxchg(&(v)->counter, oldval, newval);
70*4882a593Smuzhiyun }
71*4882a593Smuzhiyun
72*4882a593Smuzhiyun #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
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