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 This is now an alias to hw_compare_and_store, see xnu/libkern/Makefile
  58 */
  59
  60 /*
  61 Note:  We can not use the hw_atomic routines provided by osfmk/ppc as
  62 the return the result of the addition not the original value.
  63 */
  64 /*
  65 SInt32  OSDecrementAtomic(SInt32 * value)
  66 */
  67     ENTRY       _OSDecrementAtomic
  68     mr          r4, r3
  69     li          r3, -1
  70     b           _OSAddAtomic
  71
  72 /*
  73 SInt32  OSIncrementAtomic(SInt32 * value)
  74 */
  75
  76     .align      5
  77
  78     ENTRY       _OSIncrementAtomic
  79     mr          r4, r3
  80     li          r3, 1
  81
  82 /*
  83 SInt32  OSAddAtomic(SInt32 amount, SInt32 * value)
  84 */
  85
  86     ENTRY       _OSAddAtomic
  87
  88     mr          r5,r3           /* Save the increment */
  89 .L_AAretry:
  90     lwarx       r3, 0, r4       /* Grab the area value */
  91     add         r6, r3, r5      /* Add the value */
  92     stwcx.      r6, 0, r4       /* Try to save the new value */
  93     bne-        .L_AAretry      /* Didn't get it, try again... */
  94     blr                         /* Return the original value */