1#ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H
2#define _TOOLS_LINUX_ASM_X86_ATOMIC_H
3
4#include <linux/compiler.h>
5#include <linux/types.h>
6#include "rmwcc.h"
7
8#define LOCK_PREFIX "\n\tlock; "
9
10/*
11 * Atomic operations that C can't guarantee us.  Useful for
12 * resource counting etc..
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 */
23static inline int atomic_read(const atomic_t *v)
24{
25	return ACCESS_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 */
35static 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 */
46static inline void atomic_inc(atomic_t *v)
47{
48	asm volatile(LOCK_PREFIX "incl %0"
49		     : "+m" (v->counter));
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 */
60static inline int atomic_dec_and_test(atomic_t *v)
61{
62	GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
63}
64
65#endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */
66