iokit/Kernel/x86_64/IOSharedLock.s

   1 /*
   2  * Copyright (c) 1998-2010 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_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. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <architecture/i386/asm_help.h>
  25
  26         TEXT
  27
  28 /*
  29  * void
  30  * OSSpinLockUnlock(p)
  31  *      int *p;
  32  *
  33  * Unlock the lock pointed to by p.
  34  */
  35
  36 LEAF(_OSSpinLockUnlock, 0)
  37 LEAF(_IOSpinUnlock, 0)
  38 LEAF(_ev_unlock, 0)
  39         movl            $0, (%rdi)
  40 END(_OSSpinLockUnlock)
  41
  42
  43 /*
  44  * int
  45  * OSSpinLockTry(p)
  46  *      int *p;
  47  *
  48  * Try to lock p.  Return zero if not successful.
  49  */
  50
  51 LEAF(_OSSpinLockTry, 0)
  52 LEAF(_IOTrySpinLock, 0)
  53 LEAF(_ev_try_lock, 0)
  54         xorl            %eax, %eax
  55         orl             $-1, %edx
  56         lock
  57         cmpxchgl        %edx, (%rdi)
  58         setz            %dl
  59         movzbl          %dl, %eax
  60 END(_OSSpinLockTry)