1 #ifndef _ASM_X86_ATOMIC_H
2 #define _ASM_X86_ATOMIC_H
3
4 #include <linux/compiler.h>
5 #include <linux/types.h>
6 #include <asm/processor.h>
7
8 typedef struct { volatile int counter; } atomic_t;
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 */
atomic_read(const atomic_t * v)23 static 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 */
atomic_set(atomic_t * v,int i)35 static inline void atomic_set(atomic_t *v, int i)
36 {
37 v->counter = i;
38 }
39
40 /**
41 * atomic_add - add integer to atomic variable
42 * @i: integer value to add
43 * @v: pointer of type atomic_t
44 *
45 * Atomically adds @i to @v.
46 */
atomic_add(int i,atomic_t * v)47 static inline void atomic_add(int i, atomic_t *v)
48 {
49 asm volatile(LOCK_PREFIX "addl %1,%0"
50 : "+m" (v->counter)
51 : "ir" (i));
52 }
53
54 /**
55 * atomic_sub - subtract integer from atomic variable
56 * @i: integer value to subtract
57 * @v: pointer of type atomic_t
58 *
59 * Atomically subtracts @i from @v.
60 */
atomic_sub(int i,atomic_t * v)61 static inline void atomic_sub(int i, atomic_t *v)
62 {
63 asm volatile(LOCK_PREFIX "subl %1,%0"
64 : "+m" (v->counter)
65 : "ir" (i));
66 }
67
68 /**
69 * atomic_inc - increment atomic variable
70 * @v: pointer of type atomic_t
71 *
72 * Atomically increments @v by 1.
73 */
atomic_inc(atomic_t * v)74 static inline void atomic_inc(atomic_t *v)
75 {
76 asm volatile(LOCK_PREFIX "incl %0"
77 : "+m" (v->counter));
78 }
79
80 /**
81 * atomic_dec - decrement atomic variable
82 * @v: pointer of type atomic_t
83 *
84 * Atomically decrements @v by 1.
85 */
atomic_dec(atomic_t * v)86 static inline void atomic_dec(atomic_t *v)
87 {
88 asm volatile(LOCK_PREFIX "decl %0"
89 : "+m" (v->counter));
90 }
91
92 /**
93 * atomic_inc_short - increment of a short integer
94 * @v: pointer to type int
95 *
96 * Atomically adds 1 to @v
97 * Returns the new value of @u
98 */
atomic_inc_short(short int * v)99 static inline short int atomic_inc_short(short int *v)
100 {
101 asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
102 return *v;
103 }
104
105 /* These are x86-specific, used by some header files */
106 #define atomic_clear_mask(mask, addr) \
107 asm volatile(LOCK_PREFIX "andl %0,%1" \
108 : : "r" (~(mask)), "m" (*(addr)) : "memory")
109
110 #define atomic_set_mask(mask, addr) \
111 asm volatile(LOCK_PREFIX "orl %0,%1" \
112 : : "r" ((unsigned)(mask)), "m" (*(addr)) \
113 : "memory")
114
115 #endif /* _ASM_X86_ATOMIC_H */
116