libkern/ppc/OSAtomic.s

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28  /*
  29  * Copyright (c) 1997-1998 Apple Computer, Inc.
  30  *
  31  *
  32  * HISTORY
  33  *
  34  * sdouglas  22 Oct 97 - first checked in from DriverServices
  35  * sdouglas  28 Jul 98 - start IOKit
  36  */
  37
  38 #include <architecture/ppc/asm_help.h>
  39
  40 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  41 ;
  42 ; ENTRY         functionName
  43 ;
  44 ; Assembly directives to begin an exported function.
  45 ;
  46 ; Takes: functionName - name of the exported function
  47 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  48
  49 .macro ENTRY
  50     .text
  51     .align      2
  52     .globl      $0
  53 $0:
  54 .endmacro
  55
  56 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  57
  58 /*
  59 int     OSCompareAndSwap( UInt32 oldVal, UInt32 newVal, UInt32 * addr )
  60     This is now an alias to hw_compare_and_store, see xnu/libkern/Makefile.
  61
  62 void *  OSDequeueAtomic(void ** inList, SInt32 inOffset)
  63     This is also aliased, to hw_dequeue_atomic.
  64
  65 void    OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
  66     This is aliased to hw_queue_atomic.
  67 */
  68
  69 /*
  70 Note:  We can not use the hw_atomic routines provided by osfmk/ppc as
  71 the return the result of the addition not the original value.
  72 */
  73 /*
  74 SInt32  OSDecrementAtomic(SInt32 * value)
  75 */
  76     ENTRY       _OSDecrementAtomic
  77     mr          r4, r3
  78     li          r3, -1
  79     b           _OSAddAtomic
  80
  81 /*
  82 SInt32  OSIncrementAtomic(SInt32 * value)
  83 */
  84
  85     .align      5
  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 */