iokit/Kernel/i386/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            4(%esp), %ecx
  40         movl            $0, (%ecx)
  41 END(_OSSpinLockUnlock)
  42
  43
  44 /*
  45  * int
  46  * OSSpinLockTry(p)
  47  *      int *p;
  48  *
  49  * Try to lock p.  Return zero if not successful.
  50  */
  51
  52 LEAF(_OSSpinLockTry, 0)
  53 LEAF(_IOTrySpinLock, 0)
  54 LEAF(_ev_try_lock, 0)
  55         movl            4(%esp), %ecx
  56         xorl            %eax, %eax
  57         lock
  58         cmpxchgl        %ecx, (%ecx)
  59         jne     1f
  60         movl    $1, %eax                /* yes */
  61         ret
  62 1:
  63         xorl    %eax, %eax              /* no */
  64 END(_OSSpinLockTry)