MdePkg/Library/BaseLib/Ia32/Monitor.c

   1 /** @file
   2   AsmMonitor function
   3
   4   Copyright (c) 2006 - 2008, 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   Sets up a monitor buffer that is used by AsmMwait().
  17
  18   Executes a MONITOR instruction with the register state specified by Eax, Ecx
  19   and Edx. Returns Eax. This function is only available on IA-32 and X64.
  20
  21   @param  RegisterEax The value to load into EAX or RAX before executing the MONITOR
  22                       instruction.
  23   @param  RegisterEcx The value to load into ECX or RCX before executing the MONITOR
  24                       instruction.
  25   @param  RegisterEdx The value to load into EDX or RDX before executing the MONITOR
  26                       instruction.
  27
  28   @return RegisterEax
  29
  30 **/
  31 UINTN
  32 EFIAPI
  33 AsmMonitor (
  34   IN      UINTN                     RegisterEax,
  35   IN      UINTN                     RegisterEcx,
  36   IN      UINTN                     RegisterEdx
  37   )
  38 {
  39   _asm {
  40     mov     eax, RegisterEax
  41     mov     ecx, RegisterEcx
  42     mov     edx, RegisterEdx
  43     _emit   0x0f             // monitor
  44     _emit   0x01
  45     _emit   0xc8
  46   }
  47 }
  48