1 /* $NetBSD: atomic_sub_32_cas.c,v 1.2 2014/06/23 21:53:45 joerg Exp $ */
2
3 /*-
4 * Copyright (c) 2014 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/atomic.h>
33
34 uint32_t fetch_and_sub_4(volatile uint32_t *, uint32_t, ...)
35 asm("__sync_fetch_and_sub_4");
36 uint32_t sub_and_fetch_4(volatile uint32_t *, uint32_t, ...)
37 asm("__sync_sub_and_fetch_4");
38
39 uint32_t
fetch_and_sub_4(volatile uint32_t * addr,uint32_t val,...)40 fetch_and_sub_4(volatile uint32_t *addr, uint32_t val, ...)
41 {
42 uint32_t old, new;
43
44 do {
45 old = *addr;
46 new = old - val;
47 } while (atomic_cas_32(addr, old, new) != old);
48 return old;
49 }
50
51 uint32_t
sub_and_fetch_4(volatile uint32_t * addr,uint32_t val,...)52 sub_and_fetch_4(volatile uint32_t *addr, uint32_t val, ...)
53 {
54 uint32_t old, new;
55
56 do {
57 old = *addr;
58 new = old - val;
59 } while (atomic_cas_32(addr, old, new) != old);
60 return new;
61 }
62
63 __strong_alias(__atomic_fetch_sub_4,__sync_fetch_and_sub_4)
64