1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /******************************************************************************
3 *
4 * Copyright © International Business Machines Corp., 2009
5 *
6 * DESCRIPTION
7 * GCC atomic builtin wrappers
8 * http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
9 *
10 * AUTHOR
11 * Darren Hart <dvhart@linux.intel.com>
12 *
13 * HISTORY
14 * 2009-Nov-17: Initial version by Darren Hart <dvhart@linux.intel.com>
15 *
16 *****************************************************************************/
17
18 #ifndef _ATOMIC_H
19 #define _ATOMIC_H
20
21 typedef struct {
22 volatile int val;
23 } atomic_t;
24
25 #define ATOMIC_INITIALIZER { 0 }
26
27 /**
28 * atomic_cmpxchg() - Atomic compare and exchange
29 * @uaddr: The address of the futex to be modified
30 * @oldval: The expected value of the futex
31 * @newval: The new value to try and assign the futex
32 *
33 * Return the old value of addr->val.
34 */
35 static inline int
36 atomic_cmpxchg(atomic_t *addr, int oldval, int newval)
37 {
38 return __sync_val_compare_and_swap(&addr->val, oldval, newval);
39 }
40
41 /**
42 * atomic_inc() - Atomic incrememnt
43 * @addr: Address of the variable to increment
44 *
45 * Return the new value of addr->val.
46 */
47 static inline int
48 atomic_inc(atomic_t *addr)
49 {
50 return __sync_add_and_fetch(&addr->val, 1);
51 }
52
53 /**
54 * atomic_dec() - Atomic decrement
55 * @addr: Address of the variable to decrement
56 *
57 * Return the new value of addr-val.
58 */
59 static inline int
60 atomic_dec(atomic_t *addr)
61 {
62 return __sync_sub_and_fetch(&addr->val, 1);
63 }
64
65 /**
66 * atomic_set() - Atomic set
67 * @addr: Address of the variable to set
68 * @newval: New value for the atomic_t
69 *
70 * Return the new value of addr->val.
71 */
72 static inline int
73 atomic_set(atomic_t *addr, int newval)
74 {
75 addr->val = newval;
76 return newval;
77 }
78
79 #endif