/*
 * 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
 *
 */

/*
 * Multiprocessor locks used within the shared memory area between the
 * kernel and event system.  These must work in both user and kernel mode.
 * 
 * These routines are public, for the purpose of writing frame buffer device
 * drivers which handle their own cursors.  Certain architectures define a
 * generic display class which handles cursor drawing and is subclassed by
 * driver writers.  These drivers need not be concerned with the following
 * types and definitions.
 *
 * The ev_lock(), ev_unlock(), and ev_try_lock() functions are available only
 * to drivers built in or dynamically loaded into the kernel, and to DPS
 * drivers built in or dynamically loaded into the Window Server.  They do not
 * exist in any shared library.
 *
 * --> They're now in IOKit user lib.
 */

#ifndef _IOKIT_IOSHAREDLOCK_H
#define _IOKIT_IOSHAREDLOCK_H

#ifdef __cplusplus
extern "C" {
#endif

// should be 32 bytes on PPC
typedef volatile int		IOSharedLockData;
typedef IOSharedLockData    *   IOSharedLock;

#define IOSpinLockInit(l)	(*(l) = (IOSpinLockData)0)

extern void IOSpinLock(IOSharedLock l);
extern void IOSpinUnlock(IOSharedLock l);
extern boolean_t IOTrySpinLock(IOSharedLock l);

/* exact same stuff & implementation */

typedef IOSharedLockData 	ev_lock_data_t;
typedef ev_lock_data_t	    *	ev_lock_t;

#define ev_init_lock(l)		(*(l) = (ev_lock_data_t)0)
// needs isync?
//#define ev_is_locked(l)	(*(l) != (ev_lock_data_t)0)

extern void ev_lock(ev_lock_t l);		// Spin lock!
extern void ev_unlock(ev_lock_t l);
extern boolean_t ev_try_lock(ev_lock_t l);

#ifdef __cplusplus
}
#endif
#endif /* ! _IOKIT_IOSHAREDLOCK_H */
