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 **/
  14
  15 #include "BaseLibInternals.h"
  16
  17 /**
  18   Performs an atomic increment of an 32-bit unsigned integer.
  19
  20   Performs an atomic increment of the 32-bit unsigned integer specified by
  21   Value and returns the incremented value. The increment operation must be
  22   performed using MP safe mechanisms. The state of the return value is not
  23   guaranteed to be MP safe.
  24
  25   @param  Value A pointer to the 32-bit value to increment.
  26
  27   @return The incremented value.
  28
  29 **/
  30 UINT32
  31 EFIAPI
  32 InternalSyncIncrement (
  33   IN      volatile UINT32           *Value
  34   )
  35 {
  36   UINT32                            OriginalValue;
  37
  38   do {
  39     OriginalValue = *Value;
  40   } while (OriginalValue != InternalSyncCompareExchange32 (
  41                               Value,
  42                               OriginalValue,
  43                               OriginalValue + 1
  44                               ));
  45   return OriginalValue + 1;
  46 }
  47
  48 /**
  49   Performs an atomic decrement of an 32-bit unsigned integer.
  50
  51   Performs an atomic decrement of the 32-bit unsigned integer specified by
  52   Value and returns the decrement value. The decrement operation must be
  53   performed using MP safe mechanisms. The state of the return value is not
  54   guaranteed to be MP safe.
  55
  56   @param  Value A pointer to the 32-bit value to decrement.
  57
  58   @return The decrement value.
  59
  60 **/
  61 UINT32
  62 EFIAPI
  63 InternalSyncDecrement (
  64   IN      volatile UINT32           *Value
  65   )
  66 {
  67   UINT32                            OriginalValue;
  68
  69   do {
  70     OriginalValue = *Value;
  71   } while (OriginalValue != InternalSyncCompareExchange32 (
  72                               Value,
  73                               OriginalValue,
  74                               OriginalValue - 1
  75                               ));
  76   return OriginalValue - 1;
  77 }