MdePkg: Replace BSD License with BSD+Patent License

[mirror_edk2.git] / MdePkg / Library / BaseSynchronizationLib / Ia32 / InterlockedCompareExchange64.c

/** @file\r
  InterlockedCompareExchange64 function\r
\r
  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>\r
  SPDX-License-Identifier: BSD-2-Clause-Patent\r
\r
**/\r
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/**\r
  Performs an atomic compare exchange operation on a 64-bit unsigned integer.\r
\r
  Performs an atomic compare exchange operation on the 64-bit unsigned integer specified\r
  by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and\r
  CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.\r
  The compare exchange operation must be performed using MP safe mechanisms.\r
\r
  @param  Value         A pointer to the 64-bit value for the compare exchange\r
                        operation.\r
  @param  CompareValue  A 64-bit value used in a compare operation.\r
  @param  ExchangeValue A 64-bit value used in an exchange operation.\r
\r
  @return The original *Value before exchange.\r
\r
**/\r
UINT64\r
EFIAPI\r
InternalSyncCompareExchange64 (\r
  IN      volatile UINT64           *Value,\r
  IN      UINT64                    CompareValue,\r
  IN      UINT64                    ExchangeValue\r
  )\r
{\r
  _asm {\r
    mov     esi, Value\r
    mov     eax, dword ptr [CompareValue + 0]\r
    mov     edx, dword ptr [CompareValue + 4]\r
    mov     ebx, dword ptr [ExchangeValue + 0]\r
    mov     ecx, dword ptr [ExchangeValue + 4]\r
    lock    cmpxchg8b   qword ptr [esi]\r
  }\r
}\r