MdePkg/Library/BaseLib/Ia32/Monitor.c

   1 /** @file
   2   AsmMonitor function
   3
   4   Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 /**
  10   Sets up a monitor buffer that is used by AsmMwait().
  11
  12   Executes a MONITOR instruction with the register state specified by Eax, Ecx
  13   and Edx. Returns Eax. This function is only available on IA-32 and x64.
  14
  15   @param  RegisterEax The value to load into EAX or RAX before executing the MONITOR
  16                       instruction.
  17   @param  RegisterEcx The value to load into ECX or RCX before executing the MONITOR
  18                       instruction.
  19   @param  RegisterEdx The value to load into EDX or RDX before executing the MONITOR
  20                       instruction.
  21
  22   @return RegisterEax
  23
  24 **/
  25 UINTN
  26 EFIAPI
  27 AsmMonitor (
  28   IN      UINTN                     RegisterEax,
  29   IN      UINTN                     RegisterEcx,
  30   IN      UINTN                     RegisterEdx
  31   )
  32 {
  33   _asm {
  34     mov     eax, RegisterEax
  35     mov     ecx, RegisterEcx
  36     mov     edx, RegisterEdx
  37     _emit   0x0f             // monitor
  38     _emit   0x01
  39     _emit   0xc8
  40   }
  41 }
  42