projects / apple / xnu.git / blame
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|---|---|---|
| 1c79356b A |
1 | /* |
| 2 | * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved. | |
| 3 | * | |
| 4 | * @APPLE_LICENSE_HEADER_START@ | |
| 5 | * | |
| d7e50217 | 6 | * Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved. |
| 1c79356b | 7 | * |
| d7e50217 A |
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 | |
| 1c79356b A |
17 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
| 18 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| d7e50217 A |
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. | |
| 1c79356b A |
22 | * |
| 23 | * @APPLE_LICENSE_HEADER_END@ | |
| 24 | */ | |
| 25 | /* | |
| 26 | * Copyright (c) 1998 Apple Computer, Inc. All rights reserved. | |
| 27 | * | |
| 28 | * HISTORY | |
| 29 | * | |
| 30 | */ | |
| 31 | ||
| 32 | /* Copyright (c) 1992 NeXT Computer, Inc. All rights reserved. | |
| 33 | * | |
| 34 | * EventShmemLock.h - Shared memory area locks for use between the | |
| 35 | * WindowServer and the Event Driver. | |
| 36 | * | |
| 37 | * | |
| 38 | * HISTORY | |
| 39 | * 29 April 1992 Mike Paquette at NeXT | |
| 40 | * Created. | |
| 41 | * | |
| 42 | * Multiprocessor locks used within the shared memory area between the | |
| 43 | * kernel and event system. These must work in both user and kernel mode. | |
| 44 | * The locks are defined in an include file so they get exported to the local | |
| 45 | * include file area. | |
| 46 | * | |
| 47 | * This is basically a ripoff of the spin locks under the cthreads packages. | |
| 48 | */ | |
| 49 | ||
| 50 | #ifndef _IOKIT_IOSHAREDLOCKIMP_H | |
| 51 | #define _IOKIT_IOSHAREDLOCKIMP_H | |
| 52 | ||
| 53 | #include <architecture/i386/asm_help.h> | |
| 54 | ||
| 55 | // 'Till we're building in kernel | |
| 56 | .macro DISABLE_PREEMPTION | |
| 57 | #ifdef KERNEL | |
| 58 | #endif | |
| 59 | .endmacro | |
| 60 | .macro ENABLE_PREEMPTION | |
| 61 | #ifdef KERNEL | |
| 62 | #endif | |
| 63 | .endmacro | |
| 64 | ||
| 65 | /* | |
| 66 | * void | |
| 67 | * ev_lock(p) | |
| 68 | * int *p; | |
| 69 | * | |
| 70 | * Lock the lock pointed to by p. Spin (possibly forever) until the next | |
| 71 | * lock is available. | |
| 72 | */ | |
| 73 | TEXT | |
| 74 | ||
| 75 | #ifndef KERNEL | |
| 76 | LEAF(_ev_lock, 0) | |
| 77 | LEAF(_IOSpinLock, 0) | |
| 78 | push %eax | |
| 79 | push %ecx | |
| 80 | movl $1, %ecx | |
| 81 | movl 12(%esp), %eax | |
| 82 | _spin: | |
| 83 | xchgl %ecx,0(%eax) | |
| 84 | cmp $0, %ecx | |
| 85 | jne _spin | |
| 86 | pop %ecx | |
| 87 | pop %eax | |
| 88 | END(_ev_lock) | |
| 89 | #endif | |
| 90 | ||
| 91 | /* | |
| 92 | * void | |
| 93 | * ev_unlock(p) | |
| 94 | * int *p; | |
| 95 | * | |
| 96 | * Unlock the lock pointed to by p. | |
| 97 | */ | |
| 98 | LEAF(_ev_unlock, 0) | |
| 99 | LEAF(_IOSpinUnlock, 0) | |
| 100 | push %eax | |
| 101 | movl 8(%esp),%eax | |
| 102 | movl $0,0(%eax) | |
| 103 | ENABLE_PREEMPTION() | |
| 104 | pop %eax | |
| 105 | END(_ev_unlock) | |
| 106 | ||
| 107 | ||
| 108 | ||
| 109 | /* | |
| 110 | * int | |
| 111 | * ev_try_lock(p) | |
| 112 | * int *p; | |
| 113 | * | |
| 114 | * Try to lock p. Return zero if not successful. | |
| 115 | */ | |
| 116 | ||
| 117 | LEAF(_ev_try_lock, 0) | |
| 118 | LEAF(_IOTrySpinLock, 0) | |
| 119 | DISABLE_PREEMPTION() | |
| 120 | movl 4(%esp), %eax | |
| 121 | lock;bts $0, 0(%eax) | |
| 122 | jb 1f | |
| 123 | movl $1, %eax /* yes */ | |
| 124 | ret | |
| 125 | 1: | |
| 126 | ENABLE_PREEMPTION() | |
| 127 | xorl %eax, %eax /* no */ | |
| 128 | END(_ev_try_lock) | |
| 129 | ||
| 130 | ||
| 131 | #endif /* ! _IOKIT_IOSHAREDLOCKIMP_H */ |