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/** @file
InterlockedCompareExchange16 function
Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
/**
Performs an atomic compare exchange operation on a 16-bit unsigned integer.
Performs an atomic compare exchange operation on the 16-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 16-bit value for the compare exchange
operation.
@param CompareValue 16-bit value used in compare operation.
@param ExchangeValue 16-bit value used in exchange operation.
@return The original *Value before exchange.
**/
UINT16
EFIAPI
InternalSyncCompareExchange16 (
IN volatile UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
_asm {
mov ecx, Value
mov ax, CompareValue
mov dx, ExchangeValue
lock cmpxchg [ecx], dx
}
}
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