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46 lines
1.3 KiB
C
46 lines
1.3 KiB
C
/** @file
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InterlockedCompareExchange16 function
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Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
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Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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/**
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Performs an atomic compare exchange operation on a 16-bit unsigned integer.
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Performs an atomic compare exchange operation on the 16-bit unsigned integer
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specified by Value. If Value is equal to CompareValue, then Value is set to
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ExchangeValue and CompareValue is returned. If Value is not equal to CompareValue,
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then Value is returned. The compare exchange operation must be performed using
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MP safe mechanisms.
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@param Value A pointer to the 16-bit value for the compare exchange
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operation.
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@param CompareValue 16-bit value used in compare operation.
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@param ExchangeValue 16-bit value used in exchange operation.
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@return The original *Value before exchange.
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**/
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UINT16
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EFIAPI
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InternalSyncCompareExchange16 (
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IN volatile UINT16 *Value,
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IN UINT16 CompareValue,
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IN UINT16 ExchangeValue
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)
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{
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_asm {
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mov ecx, Value
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mov ax, CompareValue
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mov dx, ExchangeValue
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lock cmpxchg [ecx], dx
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}
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}
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