audk/MdePkg/Library/BaseLib/Ipf/Synchronization.c

/** @file
  Implementation of synchronization functions on Itanium.

  Copyright (c) 2006, Intel Corporation<BR>
  All rights reserved. This program and the accompanying materials
  are licensed and made available under the terms and conditions of the BSD License
  which accompanies this distribution.  The full text of the license may be found at
  http://opensource.org/licenses/bsd-license.php

  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

  Module Name:  Synchronization.c

**/

/**
  Performs an atomic compare exchange operation on a 32-bit unsigned integer.

  Performs an atomic compare exchange operation on the 32-bit unsigned integer
  specified by Value.  If Value is equal to CompareValue, then Value is set to 
  ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
  then Value is returned.  The compare exchange operation must be performed using 
  MP safe mechanisms.

  @param  Value         A pointer to the 32-bit value for the compare exchange
                        operation.
  @param  CompareValue  32-bit value used in compare operation.
  @param  ExchangeValue 32-bit value used in exchange operation.

  @return The original *Value before exchange.

**/
UINT32
EFIAPI
InternalSyncCompareExchange32 (
  IN      volatile UINT32           *Value,
  IN      UINT32                    CompareValue,
  IN      UINT32                    ExchangeValue
  );

/**
  Performs an atomic increment of an 32-bit unsigned integer.

  Performs an atomic increment of the 32-bit unsigned integer specified by
  Value and returns the incremented value. The increment operation must be
  performed using MP safe mechanisms. The state of the return value is not
  guaranteed to be MP safe.

  @param  Value A pointer to the 32-bit value to increment.

  @return The incremented value.

**/
UINT32
EFIAPI
InternalSyncIncrement (
  IN      volatile UINT32           *Value
  )
{
  UINT32                            OriginalValue;

  do {
    OriginalValue = *Value;
  } while (OriginalValue != InternalSyncCompareExchange32 (
                              Value,
                              OriginalValue,
                              OriginalValue + 1
                              ));
  return OriginalValue + 1;
}

/**
  Performs an atomic decrement of an 32-bit unsigned integer.

  Performs an atomic decrement of the 32-bit unsigned integer specified by
  Value and returns the decrement value. The decrement operation must be
  performed using MP safe mechanisms. The state of the return value is not
  guaranteed to be MP safe.

  @param  Value A pointer to the 32-bit value to decrement.

  @return The decrement value.

**/
UINT32
EFIAPI
InternalSyncDecrement (
  IN      volatile UINT32           *Value
  )
{
  UINT32                            OriginalValue;

  do {
    OriginalValue = *Value;
  } while (OriginalValue != InternalSyncCompareExchange32 (
                              Value,
                              OriginalValue,
                              OriginalValue - 1
                              ));
  return OriginalValue - 1;
}