MdePkg/Library/BaseLib/Ia32/ReadGs.c

   1 /** @file
   2   AsmReadGs 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
  17
  18 /**
  19   Reads the current value of GS Data Segment Register (GS).
  20
  21   Reads and returns the current value of GS. This function is only available on
  22   IA-32 and x64.
  23
  24   @return The current value of GS.
  25
  26 **/
  27 UINT16
  28 EFIAPI
  29 AsmReadGs (
  30   VOID
  31   )
  32 {
  33   __asm {
  34     xor     eax, eax
  35     mov     ax, gs
  36   }
  37 }
  38