1 /* $NetBSD: atomic.h,v 1.6 2014/12/10 04:38:00 christos Exp $ */
2
3 /*
4 * Copyright (C) 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
5 *
6 * Permission to use, copy, modify, and/or distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
11 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
12 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
13 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
14 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
15 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
16 * PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 /* Id: atomic.h,v 1.4 2007/06/19 23:47:18 tbox Exp */
20
21 #ifndef ISC_ATOMIC_H
22 #define ISC_ATOMIC_H 1
23
24 #include <isc/platform.h>
25 #include <isc/types.h>
26
27 /* XXX: These are not atomic! */
28 /*
29 * This routine atomically increments the value stored in 'p' by 'val', and
30 * returns the previous value.
31 */
32 static __inline isc_int32_t
isc_atomic_xadd(isc_int32_t * p,isc_int32_t val)33 isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) {
34 isc_int32_t prev = *p;
35
36 *p += val;
37
38 return prev;
39 }
40
41 /*
42 * This routine atomically stores the value 'val' in 'p'.
43 */
44 static __inline void
isc_atomic_store(isc_int32_t * p,isc_int32_t val)45 isc_atomic_store(isc_int32_t *p, isc_int32_t val) {
46 *p = val;
47 }
48
49 /*
50 * This routine atomically replaces the value in 'p' with 'val', if the
51 * original value is equal to 'cmpval'. The original value is returned in any
52 * case.
53 */
54 static __inline isc_int32_t
isc_atomic_cmpxchg(isc_int32_t * p,isc_int32_t cmpval,isc_int32_t val)55 isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
56 isc_int32_t prev = *p;
57
58 if (*p == cmpval)
59 *p = val;
60
61 return prev;
62 }
63
64 #endif /* ISC_ATOMIC_H */
65