libkern/ppc/OSAtomic.s

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25  /*
  26  * Copyright (c) 1997-1998 Apple Computer, Inc.
  27  *
  28  *
  29  * HISTORY
  30  *
  31  * sdouglas  22 Oct 97 - first checked in from DriverServices
  32  * sdouglas  28 Jul 98 - start IOKit
  33  */
  34
  35 #include <architecture/ppc/asm_help.h>
  36
  37 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  38 ;
  39 ; ENTRY         functionName
  40 ;
  41 ; Assembly directives to begin an exported function.
  42 ;
  43 ; Takes: functionName - name of the exported function
  44 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  45
  46 .macro ENTRY
  47         .text
  48         .align          2
  49         .globl          $0
  50 $0:
  51 .endmacro
  52
  53 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  54
  55 /*
  56 int OSCompareAndSwap( UInt32 oldVal, UInt32 newVal, UInt32 * addr )
  57 */
  58
  59
  60         ENTRY   _OSCompareAndSwap
  61 .L_CASretry:
  62         lwarx   r6,     0,r5
  63         cmpw    r6,     r3
  64         bne-    .L_CASfail
  65         stwcx.  r4,     0,r5
  66         bne-    .L_CASretry
  67         isync
  68         li      r3,     1
  69         blr
  70 .L_CASfail:
  71         li      r3,     0
  72         blr
  73
  74
  75 /*
  76 SInt32  OSDecrementAtomic(SInt32 * value)
  77 */
  78         ENTRY   _OSDecrementAtomic
  79         mr      r4, r3
  80         li      r3, -1
  81         b       _OSAddAtomic
  82
  83 /*
  84 SInt32  OSIncrementAtomic(SInt32 * value)
  85 */
  86
  87         ENTRY   _OSIncrementAtomic
  88         mr      r4, r3
  89         li      r3, 1
  90
  91 /*
  92 SInt32  OSAddAtomic(SInt32 amount, SInt32 * value)
  93 */
  94
  95         ENTRY   _OSAddAtomic
  96
  97         mr      r5,r3                           /* Save the increment */
  98 .L_AAretry:
  99         lwarx   r3, 0, r4                       /* Grab the area value */
 100         add     r6, r3, r5                      /* Add the value */
 101         stwcx.  r6, 0, r4                       /* Try to save the new value */
 102         bne-    .L_AAretry                      /* Didn't get it, try again... */
 103         blr                                     /* Return the original value */