/* * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * The contents of this file constitute Original Code as defined in and * are subject to the Apple Public Source License Version 1.1 (the * "License"). You may not use this file except in compliance with the * License. Please obtain a copy of the License at * http://www.apple.com/publicsource and read it before using this file. * * This Original Code and all software distributed under the License are * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the * License for the specific language governing rights and limitations * under the License. * * @APPLE_LICENSE_HEADER_END@ */ /* * Copyright (c) 1998 Apple Computer, Inc. All rights reserved. * * HISTORY * */ /* Copyright (c) 1992 NeXT Computer, Inc. All rights reserved. * * EventShmemLock.h - Shared memory area locks for use between the * WindowServer and the Event Driver. * * * HISTORY * 29 April 1992 Mike Paquette at NeXT * Created. * * Multiprocessor locks used within the shared memory area between the * kernel and event system. These must work in both user and kernel mode. * The locks are defined in an include file so they get exported to the local * include file area. * * This is basically a ripoff of the spin locks under the cthreads packages. */ #ifndef _IOKIT_IOSHAREDLOCKIMP_H #define _IOKIT_IOSHAREDLOCKIMP_H #include <architecture/i386/asm_help.h> /* * void * ev_lock(p) * int *p; * * Lock the lock pointed to by p. Spin (possibly forever) until the next * lock is available. */ TEXT #ifndef KERNEL LEAF(_ev_lock, 0) LEAF(_IOSpinLock, 0) movl 4(%esp), %ecx 0: xorl %eax, %eax rep nop /* pause for hyperthreaded CPU's */ lock cmpxchgl %ecx, (%ecx) jne 0b ret END(_ev_lock) #endif /* * void * ev_unlock(p) * int *p; * * Unlock the lock pointed to by p. */ LEAF(_ev_unlock, 0) LEAF(_IOSpinUnlock, 0) movl 4(%esp), %ecx movl $0, (%ecx) ret END(_ev_unlock) /* * int * ev_try_lock(p) * int *p; * * Try to lock p. Return zero if not successful. */ LEAF(_ev_try_lock, 0) LEAF(_IOTrySpinLock, 0) movl 4(%esp), %ecx xorl %eax, %eax lock cmpxchgl %ecx, (%ecx) jne 1f movl $1, %eax /* yes */ ret 1: xorl %eax, %eax /* no */ END(_ev_try_lock) #endif /* ! _IOKIT_IOSHAREDLOCKIMP_H */