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   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
  11
  12   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
  13   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
  14   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
  15   The compare exchange operation must be performed using MP safe mechanisms.
  16
  17   @param  Value         A pointer to the 64-bit value for the compare exchange
  18                         operation.
  19   @param  CompareValue  A 64-bit value used in a compare operation.
  20   @param  ExchangeValue A 64-bit value used in an exchange operation.
  21
  22   @return The original *Value before exchange.
  23
  24 **/
  25 UINT64
  26 EFIAPI
  27 InternalSyncCompareExchange64 (
  28   IN      volatile UINT64  *Value,
  29   IN      UINT64           CompareValue,
  30   IN      UINT64           ExchangeValue
  31   )
  32 {
  33   _asm {
  34     mov     esi, Value
  35     mov     eax, dword ptr [CompareValue + 0]
  36     mov     edx, dword ptr [CompareValue + 4]
  37     mov     ebx, dword ptr [ExchangeValue + 0]
  38     mov     ecx, dword ptr [ExchangeValue + 4]
  39     lock    cmpxchg8b   qword ptr [esi]
  40   }
  41 }