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 #include <linux/bitops.h>
8 
9 /*
10  * Atomic operations that C can't guarantee us.  Useful for
11  * resource counting etc..
12  *
13  * Excerpts obtained from the Linux kernel sources.
14  */
15 
16 #define ATOMIC_INIT(i)	{ (i) }
17 
18 /**
19  * atomic_read - read atomic variable
20  * @v: pointer of type atomic_t
21  *
22  * Atomically reads the value of @v.
23  */
24 static inline int atomic_read(const atomic_t *v)
25 {
26 	return READ_ONCE((v)->counter);
27 }
28 
29 /**
30  * atomic_set - set atomic variable
31  * @v: pointer of type atomic_t
32  * @i: required value
33  *
34  * Atomically sets the value of @v to @i.
35  */
36 static inline void atomic_set(atomic_t *v, int i)
37 {
38         v->counter = i;
39 }
40 
41 /**
42  * atomic_inc - increment atomic variable
43  * @v: pointer of type atomic_t
44  *
45  * Atomically increments @v by 1.
46  */
47 static inline void atomic_inc(atomic_t *v)
48 {
49 	__sync_add_and_fetch(&v->counter, 1);
50 }
51 
52 /**
53  * atomic_dec_and_test - decrement and test
54  * @v: pointer of type atomic_t
55  *
56  * Atomically decrements @v by 1 and
57  * returns true if the result is 0, or false for all other
58  * cases.
59  */
60 static inline int atomic_dec_and_test(atomic_t *v)
61 {
62 	return __sync_sub_and_fetch(&v->counter, 1) == 0;
63 }
64 
65 #define cmpxchg(ptr, oldval, newval) \
66 	__sync_val_compare_and_swap(ptr, oldval, newval)
67 
68 static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
69 {
70 	return cmpxchg(&(v)->counter, oldval, newval);
71 }
72 
73 static inline int test_and_set_bit(long nr, unsigned long *addr)
74 {
75 	unsigned long mask = BIT_MASK(nr);
76 	long old;
77 
78 	addr += BIT_WORD(nr);
79 
80 	old = __sync_fetch_and_or(addr, mask);
81 	return !!(old & mask);
82 }
83 
84 static inline int test_and_clear_bit(long nr, unsigned long *addr)
85 {
86 	unsigned long mask = BIT_MASK(nr);
87 	long old;
88 
89 	addr += BIT_WORD(nr);
90 
91 	old = __sync_fetch_and_and(addr, ~mask);
92 	return !!(old & mask);
93 }
94 
95 #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
96