MdePkg/Library/BaseLib/Ipf/Synchronization.c

   1 /** @file
   2   Implementation of synchronization functions on Itanium.
   3
   4   Copyright (c) 2006, Intel Corporation<BR>
   5   All rights reserved. This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13   Module Name:  Synchronization.c
  14
  15 **/
  16
  17 /**
  18   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
  19
  20   Performs an atomic compare exchange operation on the 32-bit unsigned integer
  21   specified by Value.  If Value is equal to CompareValue, then Value is set to
  22   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
  23   then Value is returned.  The compare exchange operation must be performed using
  24   MP safe mechanisms.
  25
  26   @param  Value         A pointer to the 32-bit value for the compare exchange
  27                         operation.
  28   @param  CompareValue  32-bit value used in compare operation.
  29   @param  ExchangeValue 32-bit value used in exchange operation.
  30
  31   @return The original *Value before exchange.
  32
  33 **/
  34 UINT32
  35 EFIAPI
  36 InternalSyncCompareExchange32 (
  37   IN      volatile UINT32           *Value,
  38   IN      UINT32                    CompareValue,
  39   IN      UINT32                    ExchangeValue
  40   );
  41
  42 /**
  43   Performs an atomic increment of an 32-bit unsigned integer.
  44
  45   Performs an atomic increment of the 32-bit unsigned integer specified by
  46   Value and returns the incremented value. The increment operation must be
  47   performed using MP safe mechanisms. The state of the return value is not
  48   guaranteed to be MP safe.
  49
  50   @param  Value A pointer to the 32-bit value to increment.
  51
  52   @return The incremented value.
  53
  54 **/
  55 UINT32
  56 EFIAPI
  57 InternalSyncIncrement (
  58   IN      volatile UINT32           *Value
  59   )
  60 {
  61   UINT32                            OriginalValue;
  62
  63   do {
  64     OriginalValue = *Value;
  65   } while (OriginalValue != InternalSyncCompareExchange32 (
  66                               Value,
  67                               OriginalValue,
  68                               OriginalValue + 1
  69                               ));
  70   return OriginalValue + 1;
  71 }
  72
  73 /**
  74   Performs an atomic decrement of an 32-bit unsigned integer.
  75
  76   Performs an atomic decrement of the 32-bit unsigned integer specified by
  77   Value and returns the decrement value. The decrement operation must be
  78   performed using MP safe mechanisms. The state of the return value is not
  79   guaranteed to be MP safe.
  80
  81   @param  Value A pointer to the 32-bit value to decrement.
  82
  83   @return The decrement value.
  84
  85 **/
  86 UINT32
  87 EFIAPI
  88 InternalSyncDecrement (
  89   IN      volatile UINT32           *Value
  90   )
  91 {
  92   UINT32                            OriginalValue;
  93
  94   do {
  95     OriginalValue = *Value;
  96   } while (OriginalValue != InternalSyncCompareExchange32 (
  97                               Value,
  98                               OriginalValue,
  99                               OriginalValue - 1
 100                               ));
 101   return OriginalValue - 1;
 102 }