iokit/IOKit/i386/IOSharedLockImp.h

   1 /*
   2  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
  30  *
  31  * HISTORY
  32  *
  33  */
  34
  35 /*      Copyright (c) 1992 NeXT Computer, Inc.  All rights reserved.
  36  *
  37  * EventShmemLock.h -   Shared memory area locks for use between the
  38  *                      WindowServer and the Event Driver.
  39  *
  40  *
  41  * HISTORY
  42  * 29 April 1992    Mike Paquette at NeXT
  43  *      Created.
  44  *
  45  * Multiprocessor locks used within the shared memory area between the
  46  * kernel and event system.  These must work in both user and kernel mode.
  47  * The locks are defined in an include file so they get exported to the local
  48  * include file area.
  49  *
  50  * This is basically a ripoff of the spin locks under the cthreads packages.
  51  */
  52
  53 #ifndef _IOKIT_IOSHAREDLOCKIMP_H
  54 #define _IOKIT_IOSHAREDLOCKIMP_H
  55
  56 #include <architecture/i386/asm_help.h>
  57
  58 #ifndef KERNEL
  59 #error this file for kernel only; comm page has user versions
  60 #endif
  61
  62         TEXT
  63
  64 /*
  65  * void
  66  * ev_unlock(p)
  67  *      int *p;
  68  *
  69  * Unlock the lock pointed to by p.
  70  */
  71 LEAF(_ev_unlock, 0)
  72 LEAF(_IOSpinUnlock, 0)
  73 #if __x86_64__
  74         movl            $0, (%rdi)
  75 #else
  76         movl            4(%esp), %ecx
  77         movl            $0, (%ecx)
  78 #endif
  79 END(_ev_unlock)
  80
  81
  82 /*
  83  * int
  84  * ev_try_lock(p)
  85  *      int *p;
  86  *
  87  * Try to lock p.  Return zero if not successful.
  88  */
  89
  90 LEAF(_ev_try_lock, 0)
  91 LEAF(_IOTrySpinLock, 0)
  92 #if __x86_64__
  93         xorl            %eax, %eax
  94         orl             $-1, %edx
  95         lock
  96         cmpxchgl        %edx, (%rdi)
  97         setz            %dl
  98         movzbl          %dl, %eax
  99 #else
 100         movl            4(%esp), %ecx
 101         xorl            %eax, %eax
 102         lock
 103         cmpxchgl        %ecx, (%ecx)
 104         jne     1f
 105         movl    $1, %eax                /* yes */
 106         ret
 107 1:
 108         xorl    %eax, %eax              /* no */
 109 #endif
 110 END(_ev_try_lock)
 111
 112
 113 #endif /* ! _IOKIT_IOSHAREDLOCKIMP_H */