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1/******************************************************************************
2 *
3 * Copyright © International Business Machines Corp., 2009
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * DESCRIPTION
11 * GCC atomic builtin wrappers
12 * http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
13 *
14 * AUTHOR
15 * Darren Hart <dvhart@linux.intel.com>
16 *
17 * HISTORY
18 * 2009-Nov-17: Initial version by Darren Hart <dvhart@linux.intel.com>
19 *
20 *****************************************************************************/
21
22#ifndef _ATOMIC_H
23#define _ATOMIC_H
24
25typedef struct {
26 volatile int val;
27} atomic_t;
28
29#define ATOMIC_INITIALIZER { 0 }
30
31/**
32 * atomic_cmpxchg() - Atomic compare and exchange
33 * @uaddr: The address of the futex to be modified
34 * @oldval: The expected value of the futex
35 * @newval: The new value to try and assign the futex
36 *
37 * Return the old value of addr->val.
38 */
39static inline int
40atomic_cmpxchg(atomic_t *addr, int oldval, int newval)
41{
42 return __sync_val_compare_and_swap(&addr->val, oldval, newval);
43}
44
45/**
46 * atomic_inc() - Atomic incrememnt
47 * @addr: Address of the variable to increment
48 *
49 * Return the new value of addr->val.
50 */
51static inline int
52atomic_inc(atomic_t *addr)
53{
54 return __sync_add_and_fetch(&addr->val, 1);
55}
56
57/**
58 * atomic_dec() - Atomic decrement
59 * @addr: Address of the variable to decrement
60 *
61 * Return the new value of addr-val.
62 */
63static inline int
64atomic_dec(atomic_t *addr)
65{
66 return __sync_sub_and_fetch(&addr->val, 1);
67}
68
69/**
70 * atomic_set() - Atomic set
71 * @addr: Address of the variable to set
72 * @newval: New value for the atomic_t
73 *
74 * Return the new value of addr->val.
75 */
76static inline int
77atomic_set(atomic_t *addr, int newval)
78{
79 addr->val = newval;
80 return newval;
81}
82
83#endif