MdePkg/Library/BaseSynchronizationLib/Ia32/InterlockedCompareExchange64.c

   1 /** @file
   2   InterlockedCompareExchange64 function
   3
   4   Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9
  10
  11
  12 /**
  13   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
  14
  15   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
  16   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
  17   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
  18   The compare exchange operation must be performed using MP safe mechanisms.
  19
  20   @param  Value         A pointer to the 64-bit value for the compare exchange
  21                         operation.
  22   @param  CompareValue  A 64-bit value used in a compare operation.
  23   @param  ExchangeValue A 64-bit value used in an exchange operation.
  24
  25   @return The original *Value before exchange.
  26
  27 **/
  28 UINT64
  29 EFIAPI
  30 InternalSyncCompareExchange64 (
  31   IN      volatile UINT64           *Value,
  32   IN      UINT64                    CompareValue,
  33   IN      UINT64                    ExchangeValue
  34   )
  35 {
  36   _asm {
  37     mov     esi, Value
  38     mov     eax, dword ptr [CompareValue + 0]
  39     mov     edx, dword ptr [CompareValue + 4]
  40     mov     ebx, dword ptr [ExchangeValue + 0]
  41     mov     ecx, dword ptr [ExchangeValue + 4]
  42     lock    cmpxchg8b   qword ptr [esi]
  43   }
  44 }