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// 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
// 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.
//
//
EXPORT InternalSyncCompareExchange16
EXPORT InternalSyncCompareExchange32
EXPORT InternalSyncCompareExchange64
EXPORT InternalSyncIncrement
EXPORT InternalSyncDecrement
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.
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
// )
InternalSyncCompareExchange32
dmb
InternalSyncCompareExchange32Again
ldrex r3, [r0]
cmp r3, r1
bne InternalSyncCompareExchange32Fail
InternalSyncCompareExchange32Exchange
strex ip, r2, [r0]
cmp ip, #0
bne InternalSyncCompareExchange32Again
InternalSyncCompareExchange32Fail
dmb
mov r0, r3
bx lr
/**
Performs an atomic compare exchange operation on a 64-bit unsigned integer.
Performs an atomic compare exchange operation on the 64-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 64-bit value for the compare exchange
operation.
@param CompareValue 64-bit value used in compare operation.
@param ExchangeValue 64-bit value used in exchange operation.
@return The original *Value before exchange.
**/
//UINT64
//EFIAPI
//InternalSyncCompareExchange64 (
// IN volatile UINT64 *Value, // r0
// IN UINT64 CompareValue, // r2-r3
// IN UINT64 ExchangeValue // stack
// )
InternalSyncCompareExchange64
push { r4-r7 }
ldrd r4, r5, [sp, #16]
dmb
InternalSyncCompareExchange64Again
ldrexd r6, r7, [r0]
cmp r6, r2
cmpeq r7, r3
bne InternalSyncCompareExchange64Fail
InternalSyncCompareExchange64Exchange
strexd ip, r4, r5, [r0]
cmp ip, #0
bne InternalSyncCompareExchange64Again
InternalSyncCompareExchange64Fail
dmb
mov r0, r6
mov r1, r7
pop { r4-r7 }
bx lr
/**
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
// )
InternalSyncIncrement
dmb
TryInternalSyncIncrement
ldrex r1, [r0]
add r1, r1, #1
strex r2, r1, [r0]
cmp r2, #0
bne TryInternalSyncIncrement
dmb
mov r0, r1
bx lr
/**
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
// )
InternalSyncDecrement
dmb
TryInternalSyncDecrement
ldrex r1, [r0]
sub r1, r1, #1
strex r2, r1, [r0]
cmp r2, #0
bne TryInternalSyncDecrement
dmb
mov r0, r1
bx lr
END
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