libkern/ppc/OSAtomic.s

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_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.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30  /*
  31  * Copyright (c) 1997-1998 Apple Computer, Inc.
  32  *
  33  *
  34  * HISTORY
  35  *
  36  * sdouglas  22 Oct 97 - first checked in from DriverServices
  37  * sdouglas  28 Jul 98 - start IOKit
  38  */
  39
  40 #include <architecture/ppc/asm_help.h>
  41
  42 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  43 ;
  44 ; ENTRY         functionName
  45 ;
  46 ; Assembly directives to begin an exported function.
  47 ;
  48 ; Takes: functionName - name of the exported function
  49 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  50
  51 .macro ENTRY
  52     .text
  53     .align      2
  54     .globl      $0
  55 $0:
  56 .endmacro
  57
  58 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  59
  60 /*
  61 int     OSCompareAndSwap( UInt32 oldVal, UInt32 newVal, UInt32 * addr )
  62     This is now an alias to hw_compare_and_store, see xnu/libkern/Makefile.
  63
  64 void *  OSDequeueAtomic(void ** inList, SInt32 inOffset)
  65     This is also aliased, to hw_dequeue_atomic.
  66
  67 void    OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
  68     This is aliased to hw_queue_atomic.
  69 */
  70
  71 /*
  72 Note:  We can not use the hw_atomic routines provided by osfmk/ppc as
  73 the return the result of the addition not the original value.
  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     .align      5
  88
  89     ENTRY       _OSIncrementAtomic
  90     mr          r4, r3
  91     li          r3, 1
  92
  93 /*
  94 SInt32  OSAddAtomic(SInt32 amount, SInt32 * value)
  95 */
  96
  97     ENTRY       _OSAddAtomic
  98
  99     mr          r5,r3           /* Save the increment */
 100 .L_AAretry:
 101     lwarx       r3, 0, r4       /* Grab the area value */
 102     add         r6, r3, r5      /* Add the value */
 103     stwcx.      r6, 0, r4       /* Try to save the new value */
 104     bne-        .L_AAretry      /* Didn't get it, try again... */
 105     blr                         /* Return the original value */