MdePkg/Library/BaseLib/Ia32/ReadDr4.c

   1 /** @file
   2   AsmReadDr4 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   Reads the current value of Debug Register 4 (DR4).
  11
  12   Reads and returns the current value of DR4. This function is only available
  13   on IA-32 and x64. This returns a 32-bit value on IA-32 and a 64-bit value on
  14   x64.
  15
  16   @return The value of Debug Register 4 (DR4).
  17
  18 **/
  19 UINTN
  20 EFIAPI
  21 AsmReadDr4 (
  22   VOID
  23   )
  24 {
  25   __asm {
  26     _emit  0x0f
  27     _emit  0x21
  28     _emit  0xe0
  29   }
  30 }