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MdePkg/BaseSynchronizationLib: Add InterlockedCompareExchange16 

This implements the function InterlockedCompareExchange16 () for all
architectures, using architecture and toolchain specific intrinsics
or primitive assembler instructions.

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Olivier Martin <olivier.martin@arm.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16966 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Ard Biesheuvel 2015-02-28 20:31:54 +00:00 committed by lersek
parent cc3104283f
commit 9b89163eea
17 changed files with 622 additions and 0 deletions
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26
MdePkg/Include/Library/SynchronizationLib.h
View File

@ -183,6 +183,32 @@ InterlockedDecrement (
);
/**
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.
If Value is NULL, then ASSERT().
@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
InterlockedCompareExchange16 (
IN OUT UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
);
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

44
MdePkg/Library/BaseSynchronizationLib/AArch64/Synchronization.S
View File

@ -16,11 +16,55 @@
.text
.align 3
GCC_ASM_EXPORT(InternalSyncCompareExchange16)
GCC_ASM_EXPORT(InternalSyncCompareExchange32)
GCC_ASM_EXPORT(InternalSyncCompareExchange64)
GCC_ASM_EXPORT(InternalSyncIncrement)
GCC_ASM_EXPORT(InternalSyncDecrement)
/**
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_PFX(InternalSyncCompareExchange16):
uxth w1, w1
uxth w2, w2
dmb sy
InternalSyncCompareExchange16Again:
ldxrh w3, [x0]
cmp w3, w1
bne InternalSyncCompareExchange16Fail
InternalSyncCompareExchange16Exchange:
stxrh w4, w2, [x0]
cbnz w4, InternalSyncCompareExchange16Again
InternalSyncCompareExchange16Fail:
dmb sy
mov w0, w3
ret
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

44
MdePkg/Library/BaseSynchronizationLib/Arm/Synchronization.S
View File

@ -1,6 +1,7 @@
// Implementation of synchronization functions for ARM architecture
//
// Copyright (c) 2012-2015, ARM Limited. All rights reserved.
// Copyright (c) 2015, Linaro Limited. All rights reserved.
//
// This program and the accompanying materials
// are licensed and made available under the terms and conditions of the BSD License
@ -15,11 +16,54 @@
.text
.align 3
GCC_ASM_EXPORT(InternalSyncCompareExchange16)
GCC_ASM_EXPORT(InternalSyncCompareExchange32)
GCC_ASM_EXPORT(InternalSyncCompareExchange64)
GCC_ASM_EXPORT(InternalSyncIncrement)
GCC_ASM_EXPORT(InternalSyncDecrement)
/**
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_PFX(InternalSyncCompareExchange16):
dmb
InternalSyncCompareExchange16Again:
ldrexh r3, [r0]
cmp r3, r1
bne InternalSyncCompareExchange16Fail
InternalSyncCompareExchange16Exchange:
strexh ip, r2, [r0]
cmp ip, #0
bne InternalSyncCompareExchange16Again
InternalSyncCompareExchange16Fail:
dmb
mov r0, r3
bx lr
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

44
MdePkg/Library/BaseSynchronizationLib/Arm/Synchronization.asm
View File

@ -1,6 +1,7 @@
// Implementation of synchronization functions for ARM architecture
//
// Copyright (c) 2012-2015, ARM Limited. All rights reserved.
// Copyright (c) 2015, Linaro Limited. All rights reserved.
//
// This program and the accompanying materials
// are licensed and made available under the terms and conditions of the BSD License
@ -12,6 +13,7 @@
//
//
EXPORT InternalSyncCompareExchange16
EXPORT InternalSyncCompareExchange32
EXPORT InternalSyncCompareExchange64
EXPORT InternalSyncIncrement
@ -19,6 +21,48 @@
AREA ArmSynchronization, CODE, READONLY
/**
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
// )
InternalSyncCompareExchange16
dmb
InternalSyncCompareExchange16Again
ldrexh r3, [r0]
cmp r3, r1
bne InternalSyncCompareExchange16Fail
InternalSyncCompareExchange16Exchange
strexh ip, r2, [r0]
cmp ip, #0
bne InternalSyncCompareExchange16Again
InternalSyncCompareExchange16Fail
dmb
mov r0, r3
bx lr
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

5
MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
View File

@ -32,12 +32,14 @@
[Sources.IA32]
Ia32/InterlockedCompareExchange64.c | MSFT
Ia32/InterlockedCompareExchange32.c | MSFT
Ia32/InterlockedCompareExchange16.c | MSFT
Ia32/InterlockedDecrement.c | MSFT
Ia32/InterlockedIncrement.c | MSFT
SynchronizationMsc.c | MSFT
Ia32/InterlockedCompareExchange64.asm | INTEL
Ia32/InterlockedCompareExchange32.asm | INTEL
Ia32/InterlockedCompareExchange16.asm | INTEL
Ia32/InterlockedDecrement.asm | INTEL
Ia32/InterlockedIncrement.asm | INTEL
Synchronization.c | INTEL
@ -48,9 +50,11 @@
[Sources.X64]
X64/InterlockedCompareExchange64.c | MSFT
X64/InterlockedCompareExchange32.c | MSFT
X64/InterlockedCompareExchange16.c | MSFT
X64/InterlockedCompareExchange64.asm | INTEL
X64/InterlockedCompareExchange32.asm | INTEL
X64/InterlockedCompareExchange16.asm | INTEL
X64/InterlockedDecrement.c | MSFT
X64/InterlockedIncrement.c | MSFT
@ -67,6 +71,7 @@
Ipf/Synchronization.c
Ipf/InterlockedCompareExchange64.s
Ipf/InterlockedCompareExchange32.s
Ipf/InterlockedCompareExchange16.s
Synchronization.c | INTEL
SynchronizationMsc.c | MSFT

26
MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLibInternals.h
View File

@ -62,6 +62,32 @@ InternalSyncDecrement (
);
/**
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 A 16-bit value used in compare operation.
@param ExchangeValue A 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
);
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

31
MdePkg/Library/BaseSynchronizationLib/Ebc/Synchronization.c
View File

@ -12,6 +12,37 @@
**/
/**
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
)
{
return *Value != CompareValue ? *Value :
((*Value = ExchangeValue), CompareValue);
}
/**
Performs an atomic compare exchange operation on a 32-bit
unsigned integer.

42
MdePkg/Library/BaseSynchronizationLib/Ia32/GccInline.c
View File

@ -87,6 +87,48 @@ InternalSyncDecrement (
return Result;
}
/**
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 OUT volatile UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
__asm__ __volatile__ (
" \n\t"
"lock \n\t"
"cmpxchgw %1, %2 \n\t"
: "=a" (CompareValue)
: "q" (ExchangeValue),
"m" (*Value),
"0" (CompareValue)
: "memory",
"cc"
);
return CompareValue;
}
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

46
MdePkg/Library/BaseSynchronizationLib/Ia32/InterlockedCompareExchange16.asm Normal file
View File

@ -0,0 +1,46 @@
;------------------------------------------------------------------------------
;
; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
; Copyright (c) 2015, Linaro Ltd. 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.
;
; Module Name:
;
; InterlockedCompareExchange16.Asm
;
; Abstract:
;
; InterlockedCompareExchange16 function
;
; Notes:
;
;------------------------------------------------------------------------------
.486
.model flat,C
.code
;------------------------------------------------------------------------------
; UINT16
; EFIAPI
; InternalSyncCompareExchange16 (
; IN UINT16 *Value,
; IN UINT16 CompareValue,
; IN UINT16 ExchangeValue
; );
;------------------------------------------------------------------------------
InternalSyncCompareExchange16 PROC
mov ecx, [esp + 4]
mov ax, [esp + 8]
mov dx, [esp + 12]
lock cmpxchg [ecx], dx
ret
InternalSyncCompareExchange16 ENDP
END

51
MdePkg/Library/BaseSynchronizationLib/Ia32/InterlockedCompareExchange16.c Normal file
View File

@ -0,0 +1,51 @@
/** @file
InterlockedCompareExchange16 function
Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
Copyright (c) 2015, Linaro Ltd. 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 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 UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
_asm {
mov ecx, Value
mov ax, CompareValue
mov dx, ExchangeValue
lock cmpxchg [ecx], dx
}
}

30
MdePkg/Library/BaseSynchronizationLib/Ipf/InterlockedCompareExchange16.s Normal file
View File

@ -0,0 +1,30 @@
/// @file
/// Contains an implementation of InterlockedCompareExchange16 on Itanium-
/// based architecture.
///
/// Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
/// Copyright (c) 2015, Linaro Ltd. 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.
///
/// Module Name: InterlockedCompareExchange16.s
///
///
.auto
.text
.proc InternalSyncCompareExchange16
.type InternalSyncCompareExchange16, @function
InternalSyncCompareExchange16::
zxt2 r33 = r33
mov ar.ccv = r33
cmpxchg2.rel r8 = [r32], r34
mf
br.ret.sptk.many b0
.endp InternalSyncCompareExchange16

31
MdePkg/Library/BaseSynchronizationLib/Synchronization.c
View File

@ -276,6 +276,37 @@ InterlockedDecrement (
return InternalSyncDecrement (Value);
}
/**
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.
If Value is NULL, then ASSERT().
@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
InterlockedCompareExchange16 (
IN OUT UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
ASSERT (Value != NULL);
return InternalSyncCompareExchange16 (Value, CompareValue, ExchangeValue);
}
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

31
MdePkg/Library/BaseSynchronizationLib/SynchronizationGcc.c
View File

@ -292,6 +292,37 @@ InterlockedDecrement (
return InternalSyncDecrement (Value);
}
/**
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.
If Value is NULL, then ASSERT().
@param Value A pointer to the 16-bit value for the compare exchange
operation.
@param CompareValue A 16-bit value used in compare operation.
@param ExchangeValue A 16-bit value used in exchange operation.
@return The original *Value before exchange.
**/
UINT16
EFIAPI
InterlockedCompareExchange16 (
IN OUT UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
ASSERT (Value != NULL);
return InternalSyncCompareExchange16 (Value, CompareValue, ExchangeValue);
}
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

31
MdePkg/Library/BaseSynchronizationLib/SynchronizationMsc.c
View File

@ -294,6 +294,37 @@ InterlockedDecrement (
return InternalSyncDecrement (Value);
}
/**
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.
If Value is NULL, then ASSERT().
@param Value A pointer to the 16-bit value for the compare exchange
operation.
@param CompareValue A 16-bit value used in a compare operation.
@param ExchangeValue A 16-bit value used in an exchange operation.
@return The original *Value before exchange.
**/
UINT16
EFIAPI
InterlockedCompareExchange16 (
IN OUT UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
ASSERT (Value != NULL);
return InternalSyncCompareExchange16 (Value, CompareValue, ExchangeValue);
}
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

44
MdePkg/Library/BaseSynchronizationLib/X64/GccInline.c
View File

@ -88,6 +88,50 @@ InternalSyncDecrement (
}
/**
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 OUT volatile UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
__asm__ __volatile__ (
"lock \n\t"
"cmpxchgw %3, %1 "
: "=a" (CompareValue),
"=m" (*Value)
: "a" (CompareValue),
"r" (ExchangeValue),
"m" (*Value)
: "memory",
"cc"
);
return CompareValue;
}
/**
Performs an atomic compare exchange operation on a 32-bit unsigned integer.

42
MdePkg/Library/BaseSynchronizationLib/X64/InterlockedCompareExchange16.asm Normal file
View File

@ -0,0 +1,42 @@
;------------------------------------------------------------------------------
;
; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
; Copyright (c) 2015, Linaro Ltd. 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.
;
; Module Name:
;
; InterlockedCompareExchange16.Asm
;
; Abstract:
;
; InterlockedCompareExchange16 function
;
; Notes:
;
;------------------------------------------------------------------------------
.code
;------------------------------------------------------------------------------
; UINT16
; EFIAPI
; InterlockedCompareExchange16 (
; IN UINT16 *Value,
; IN UINT16 CompareValue,
; IN UINT16 ExchangeValue
; );
;------------------------------------------------------------------------------
InternalSyncCompareExchange16 PROC
mov ax, dx
lock cmpxchg [rcx], r8w
ret
InternalSyncCompareExchange16 ENDP
END

54
MdePkg/Library/BaseSynchronizationLib/X64/InterlockedCompareExchange16.c Normal file
View File

@ -0,0 +1,54 @@
/** @file
InterlockedCompareExchange16 function
Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
Copyright (c) 2015, Linaro Ltd. 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.
**/
/**
Microsoft Visual Studio 7.1 Function Prototypes for I/O Intrinsics.
**/
__int16 _InterlockedCompareExchange16(
__int16 volatile * Destination,
__int16 Exchange,
__int16 Comperand
);
#pragma intrinsic(_InterlockedCompareExchange16)
/**
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 UINT16 *Value,
IN UINT16 CompareValue,
IN UINT16 ExchangeValue
)
{
return _InterlockedCompareExchange16 (Value, ExchangeValue, CompareValue);
}