/* * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The 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, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_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 * 30 Nov 1992 Ben Fathi (benf@next.com) * Ported to m98k. * * 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. */ #ifndef _IOKIT_IOSHAREDLOCKIMP_H #define _IOKIT_IOSHAREDLOCKIMP_H #include <architecture/ppc/asm_help.h> #ifdef KERNEL #undef END #include <mach/ppc/asm.h> #endif /* * void * ev_lock(p) * register int *p; * * Lock the lock pointed to by p. Spin (possibly forever) until * the lock is available. Test and test and set logic used. */ TEXT #ifndef KERNEL LEAF(_ev_lock) li a6,1 // lock value 8: lwz a7,0(a0) // Get lock word mr. a7,a7 // Is it held? bne-- 8b // Yup... 9: lwarx a7,0,a0 // read the lock mr. a7,a7 // Is it held? bne-- 7f // yes, kill reservation stwcx. a6,0,a0 // try to get the lock bne-- 9b // failed, try again isync blr // got it, return 7: li a7,-4 // Point to a spot in the red zone stwcx. a7,a7,r1 // Kill reservation b 8b // Go wait some more... END(_ev_lock) LEAF(_IOSpinLock) li a6,1 // lock value 8: lwz a7,0(a0) // Get lock word mr. a7,a7 // Is it held? bne-- 8b // Yup... 9: lwarx a7,0,a0 // read the lock mr. a7,a7 // Is it held? bne-- 7f // yes, kill reservation stwcx. a6,0,a0 // try to get the lock bne-- 9b // failed, try again isync blr // got it, return 7: li a7,-4 // Point to a spot in the red zone stwcx. a7,a7,r1 // Kill reservation b 8b // Go wait some more... END(_IOSpinLock) #endif /* * void * spin_unlock(p) * int *p; * * Unlock the lock pointed to by p. */ LEAF(_ev_unlock) sync li a7,0 stw a7,0(a0) blr END(_ev_unlock) LEAF(_IOSpinUnlock) sync li a7,0 stw a7,0(a0) blr END(_IOSpinUnlock) /* * ev_try_lock(p) * int *p; * * Try to lock p. Return TRUE if successful in obtaining lock. */ LEAF(_ev_try_lock) li a6,1 // lock value lwz a7,0(a0) // Get lock word mr. a7,a7 // Is it held? bne-- 6f // Yup... 9: lwarx a7,0,a0 // read the lock mr. a7,a7 // Is it held? bne-- 7f // yes, kill reservation stwcx. a6,0,a0 // try to get the lock bne-- 9b // failed, try again li a0,1 // return TRUE isync blr // got it, return 7: li a7,-4 // Point to a spot in the red zone stwcx. a7,a7,r1 // Kill reservation 6: li a0,0 // return FALSE blr END(_ev_try_lock) LEAF(_IOTrySpinLock) li a6,1 // lock value lwz a7,0(a0) // Get lock word mr. a7,a7 // Is it held? bne-- 6f // Yup... 9: lwarx a7,0,a0 // read the lock mr. a7,a7 // Is it held? bne-- 7f // yes, kill reservation stwcx. a6,0,a0 // try to get the lock bne-- 9b // failed, try again li a0,1 // return TRUE isync blr // got it, return 7: li a7,-4 // Point to a spot in the red zone stwcx. a7,a7,r1 // Kill reservation 6: li a0,0 // return FALSE blr END(_IOTrySpinLock) #endif /* ! _IOKIT_IOSHAREDLOCKIMP_H */