libkern/ppc/OSAtomic.s

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22  /*
  23  * Copyright (c) 1997-1998 Apple Computer, Inc.
  24  *
  25  *
  26  * HISTORY
  27  *
  28  * sdouglas  22 Oct 97 - first checked in from DriverServices
  29  * sdouglas  28 Jul 98 - start IOKit
  30  */
  31
  32 #include <architecture/ppc/asm_help.h>
  33
  34 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  35 ;
  36 ; ENTRY         functionName
  37 ;
  38 ; Assembly directives to begin an exported function.
  39 ;
  40 ; Takes: functionName - name of the exported function
  41 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  42
  43 .macro ENTRY
  44     .text
  45     .align      2
  46     .globl      $0
  47 $0:
  48 .endmacro
  49
  50 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  51
  52 /*
  53 int     OSCompareAndSwap( UInt32 oldVal, UInt32 newVal, UInt32 * addr )
  54     This is now an alias to hw_compare_and_store, see xnu/libkern/Makefile.
  55
  56 void *  OSDequeueAtomic(void ** inList, SInt32 inOffset)
  57     This is also aliased, to hw_dequeue_atomic.
  58
  59 void    OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
  60     This is aliased to hw_queue_atomic.
  61 */
  62
  63 /*
  64 Note:  We can not use the hw_atomic routines provided by osfmk/ppc as
  65 the return the result of the addition not the original value.
  66 */
  67 /*
  68 SInt32  OSDecrementAtomic(SInt32 * value)
  69 */
  70     ENTRY       _OSDecrementAtomic
  71     mr          r4, r3
  72     li          r3, -1
  73     b           _OSAddAtomic
  74
  75 /*
  76 SInt32  OSIncrementAtomic(SInt32 * value)
  77 */
  78
  79     .align      5
  80
  81     ENTRY       _OSIncrementAtomic
  82     mr          r4, r3
  83     li          r3, 1
  84
  85 /*
  86 SInt32  OSAddAtomic(SInt32 amount, SInt32 * value)
  87 */
  88
  89     ENTRY       _OSAddAtomic
  90
  91     mr          r5,r3           /* Save the increment */
  92 .L_AAretry:
  93     lwarx       r3, 0, r4       /* Grab the area value */
  94     add         r6, r3, r5      /* Add the value */
  95     stwcx.      r6, 0, r4       /* Try to save the new value */
  96     bne-        .L_AAretry      /* Didn't get it, try again... */
  97     blr                         /* Return the original value */