FreeBSD/Linux Kernel Cross Reference
sys/iokit/IOKit/IOSharedLock.h

     /*
      * 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
     *
     */
    
    /*
     * 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) = (IOSharedLockData)0)
    
    #ifndef KERNEL
    extern void IOSpinLock(IOSharedLock l);
    #endif
    
    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)
    
    #ifndef KERNEL
    extern void ev_lock(ev_lock_t l);               // Spin lock!
    #endif
    
    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 */

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