MdePkg/Library/BaseLib/Ia32/Monitor.c

   1 /** @file
   2   AsmMonitor function
   3
   4   Copyright (c) 2006 - 2007, Intel Corporation<BR>
   5   All rights reserved. This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 //
  16 // Include common header file for this module.
  17 //
  18
  19
  20 /**
  21   Sets up a monitor buffer that is used by AsmMwait().
  22
  23   Executes a MONITOR instruction with the register state specified by Eax, Ecx
  24   and Edx. Returns Eax. This function is only available on IA-32 and X64.
  25
  26   @param  Eax The value to load into EAX or RAX before executing the MONITOR
  27               instruction.
  28   @param  Ecx The value to load into ECX or RCX before executing the MONITOR
  29               instruction.
  30   @param  Edx The value to load into EDX or RDX before executing the MONITOR
  31               instruction.
  32
  33   @return Eax
  34
  35 **/
  36 UINTN
  37 EFIAPI
  38 AsmMonitor (
  39   IN      UINTN                     RegisterEax,
  40   IN      UINTN                     RegisterEcx,
  41   IN      UINTN                     RegisterEdx
  42   )
  43 {
  44   _asm {
  45     mov     eax, RegisterEax
  46     mov     ecx, RegisterEcx
  47     mov     edx, RegisterEdx
  48     _emit   0x0f             // monitor
  49     _emit   0x01
  50     _emit   0xc8
  51   }
  52 }
  53