1 files changed, 50 insertions, 0 deletions
diff --git a/Core/MdePkg/Library/BaseSynchronizationLib/Ia32/InterlockedCompareExchange64.c b/Core/MdePkg/Library/BaseSynchronizationLib/Ia32/InterlockedCompareExchange64.c
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index 0000000000..73af6ef91a
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+++ b/Core/MdePkg/Library/BaseSynchronizationLib/Ia32/InterlockedCompareExchange64.c
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+/** @file
+  InterlockedCompareExchange64 function
+
+  Copyright (c) 2006 - 2010, 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 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  A 64-bit value used in a compare operation.
+  @param  ExchangeValue A 64-bit value used in an exchange operation.
+
+  @return The original *Value before exchange.
+
+**/
+UINT64
+EFIAPI
+InternalSyncCompareExchange64 (
+  IN      UINT64                    *Value,
+  IN      UINT64                    CompareValue,
+  IN      UINT64                    ExchangeValue
+  )
+{
+  _asm {
+    mov     esi, Value
+    mov     eax, dword ptr [CompareValue + 0]
+    mov     edx, dword ptr [CompareValue + 4]
+    mov     ebx, dword ptr [ExchangeValue + 0]
+    mov     ecx, dword ptr [ExchangeValue + 4]
+    lock    cmpxchg8b   qword ptr [esi]
+  }
+}