/** @file InterlockedCompareExchange32 function Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR> 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. **/ /** 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 ) { _asm { mov ecx, Value mov eax, CompareValue mov edx, ExchangeValue lock cmpxchg [ecx], edx } }