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
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