atomic.h revision 290001 
1/*
2 * Copyright (C) 2005, 2007, 2008  Internet Systems Consortium, Inc. ("ISC")
3 *
4 * Permission to use, copy, modify, and/or distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
9 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
10 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
11 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
12 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
13 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
14 * PERFORMANCE OF THIS SOFTWARE.
15 */
16
17/* $Id: atomic.h,v 1.6 2008/01/24 23:47:00 tbox Exp $ */
18
19#ifndef ISC_ATOMIC_H
20#define ISC_ATOMIC_H 1
21
22#include <isc/platform.h>
23#include <isc/types.h>
24
25#ifdef ISC_PLATFORM_USEGCCASM
26
27/* We share the gcc-version with x86_32 */
28#error "impossible case.  check build configuration"
29
30#elif defined(ISC_PLATFORM_USESTDASM)
31/*
32 * The followings are "generic" assembly code which implements the same
33 * functionality in case the gcc extension cannot be used.  It should be
34 * better to avoid inlining below, since we directly refer to specific
35 * registers for arguments, which would not actually correspond to the
36 * intended address or value in the embedded mnemonic.
37 */
38#include <isc/util.h>		/* for 'UNUSED' macro */
39
40static isc_int32_t
41isc_atomic_xadd(isc_int32_t *p, isc_int32_t val) {
42	UNUSED(p);
43	UNUSED(val);
44
45	__asm (
46		"movq %rdi, %rdx\n"
47		"movl %esi, %eax\n"
48#ifdef ISC_PLATFORM_USETHREADS
49		"lock;"
50#endif
51		"xadd %eax, (%rdx)\n"
52		/*
53		 * XXX: assume %eax will be used as the return value.
54		 */
55		);
56}
57
58#ifdef ISC_PLATFORM_HAVEXADDQ
59static isc_int64_t
60isc_atomic_xaddq(isc_int64_t *p, isc_int64_t val) {
61	UNUSED(p);
62	UNUSED(val);
63
64	__asm (
65		"movq %rdi, %rdx\n"
66		"movq %rsi, %rax\n"
67#ifdef ISC_PLATFORM_USETHREADS
68		"lock;"
69#endif
70		"xaddq %rax, (%rdx)\n"
71		/*
72		 * XXX: assume %rax will be used as the return value.
73		 */
74		);
75}
76#endif
77
78static void
79isc_atomic_store(isc_int32_t *p, isc_int32_t val) {
80	UNUSED(p);
81	UNUSED(val);
82
83	__asm (
84		"movq %rdi, %rax\n"
85		"movl %esi, %edx\n"
86#ifdef ISC_PLATFORM_USETHREADS
87		"lock;"
88#endif
89		"xchgl (%rax), %edx\n"
90		/*
91		 * XXX: assume %rax will be used as the return value.
92		 */
93		);
94}
95
96static isc_int32_t
97isc_atomic_cmpxchg(isc_int32_t *p, isc_int32_t cmpval, isc_int32_t val) {
98	UNUSED(p);
99	UNUSED(cmpval);
100	UNUSED(val);
101
102	__asm (
103		"movl %edx, %ecx\n"
104		"movl %esi, %eax\n"
105		"movq %rdi, %rdx\n"
106
107#ifdef ISC_PLATFORM_USETHREADS
108		"lock;"
109#endif
110		/*
111		 * If (%rdi) == %eax then (%rdi) := %edx.
112		 * %eax is set to old (%ecx), which will be the return value.
113		 */
114		"cmpxchgl %ecx, (%rdx)"
115		);
116}
117
118#else /* !ISC_PLATFORM_USEGCCASM && !ISC_PLATFORM_USESTDASM */
119
120#error "unsupported compiler.  disable atomic ops by --disable-atomic"
121
122#endif
123#endif /* ISC_ATOMIC_H */
124