1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __TOOLS_ASM_GENERIC_ATOMIC_H
3 #define __TOOLS_ASM_GENERIC_ATOMIC_H
5 #include <linux/compiler.h>
6 #include <linux/types.h>
9 * Atomic operations that C can't guarantee us. Useful for
10 * resource counting etc..
12 * Excerpts obtained from the Linux kernel sources.
15 #define ATOMIC_INIT(i) { (i) }
18 * atomic_read - read atomic variable
19 * @v: pointer of type atomic_t
21 * Atomically reads the value of @v.
23 static inline int atomic_read(const atomic_t *v)
25 return READ_ONCE((v)->counter);
29 * atomic_set - set atomic variable
30 * @v: pointer of type atomic_t
33 * Atomically sets the value of @v to @i.
35 static inline void atomic_set(atomic_t *v, int i)
41 * atomic_inc - increment atomic variable
42 * @v: pointer of type atomic_t
44 * Atomically increments @v by 1.
46 static inline void atomic_inc(atomic_t *v)
48 __sync_add_and_fetch(&v->counter, 1);
52 * atomic_dec_and_test - decrement and test
53 * @v: pointer of type atomic_t
55 * Atomically decrements @v by 1 and
56 * returns true if the result is 0, or false for all other
59 static inline int atomic_dec_and_test(atomic_t *v)
61 return __sync_sub_and_fetch(&v->counter, 1) == 0;
64 #define cmpxchg(ptr, oldval, newval) \
65 __sync_val_compare_and_swap(ptr, oldval, newval)
67 static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
69 return cmpxchg(&(v)->counter, oldval, newval);
72 #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */