4dc31432d4fc15d92372a714f188deb8ff301ff2
[apple/xnu.git] / libkern / ppc / OSAtomic.s
1 /*
2 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
7 *
8 * This file contains Original Code and/or Modifications of Original Code
9 * as defined in and that are subject to the Apple Public Source License
10 * Version 2.0 (the 'License'). You may not use this file except in
11 * compliance with the License. Please obtain a copy of the License at
12 * http://www.opensource.apple.com/apsl/ and read it before using this
13 * file.
14 *
15 * The Original Code and all software distributed under the License are
16 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
17 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
18 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
20 * Please see the License for the specific language governing rights and
21 * limitations under the License.
22 *
23 * @APPLE_LICENSE_HEADER_END@
24 */
25 /*
26 * Copyright (c) 1997-1998 Apple Computer, Inc.
27 *
28 *
29 * HISTORY
30 *
31 * sdouglas 22 Oct 97 - first checked in from DriverServices
32 * sdouglas 28 Jul 98 - start IOKit
33 */
34
35 #include <architecture/ppc/asm_help.h>
36
37 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
38 ;
39 ; ENTRY functionName
40 ;
41 ; Assembly directives to begin an exported function.
42 ;
43 ; Takes: functionName - name of the exported function
44 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
45
46 .macro ENTRY
47 .text
48 .align 2
49 .globl $0
50 $0:
51 .endmacro
52
53 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
54
55 /*
56 int OSCompareAndSwap( UInt32 oldVal, UInt32 newVal, UInt32 * addr )
57 */
58
59
60 ENTRY _OSCompareAndSwap
61 .L_CASretry:
62 lwz r6,0(r5) // Get the swap value
63 cmpw r6,r3 // Is is the same
64 bne-- .L_CASfail2 // No...
65
66 .L_CASretry2:
67 lwarx r6,0,r5 // Get it atomically now
68 cmpw r6,r3 // Same?
69 bne-- .L_CASfail // Nope, go say so and toss reservations...
70 stwcx. r4,0,r5 // Stash the new value
71 bne-- .L_CASretry2 // Just got collision...
72 isync
73 li r3, 1
74 blr
75
76 .L_CASfail:
77 li a7,-4 // Point to a spot in the red zone
78 stwcx. a7,a7,r1 // Kill reservation
79
80 .L_CASfail2:
81 li r3, 0
82 blr
83
84
85 /*
86 SInt32 OSDecrementAtomic(SInt32 * value)
87 */
88 ENTRY _OSDecrementAtomic
89 mr r4, r3
90 li r3, -1
91 b _OSAddAtomic
92
93 /*
94 SInt32 OSIncrementAtomic(SInt32 * value)
95 */
96
97 ENTRY _OSIncrementAtomic
98 mr r4, r3
99 li r3, 1
100
101 /*
102 SInt32 OSAddAtomic(SInt32 amount, SInt32 * value)
103 */
104
105 ENTRY _OSAddAtomic
106
107 mr r5,r3 /* Save the increment */
108 .L_AAretry:
109 lwarx r3, 0, r4 /* Grab the area value */
110 add r6, r3, r5 /* Add the value */
111 stwcx. r6, 0, r4 /* Try to save the new value */
112 bne- .L_AAretry /* Didn't get it, try again... */
113 blr /* Return the original value */