MdePkg/Library/BaseLib/Ia32/CpuId.c

   1 /** @file
   2   AsmCpuid 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 #include "CommonHeader.h"
  19
  20 UINT32
  21 EFIAPI
  22 AsmCpuid (
  23   IN      UINT32                    Index,
  24   OUT     UINT32                    *RegisterEax,  OPTIONAL
  25   OUT     UINT32                    *RegisterEbx,  OPTIONAL
  26   OUT     UINT32                    *RegisterEcx,  OPTIONAL
  27   OUT     UINT32                    *RegisterEdx   OPTIONAL
  28   )
  29 {
  30   _asm {
  31     mov     eax, Index
  32     cpuid
  33     push    ecx
  34     mov     ecx, RegisterEax
  35     jecxz   SkipEax
  36     mov     [ecx], eax
  37 SkipEax:
  38     mov     ecx, RegisterEbx
  39     jecxz   SkipEbx
  40     mov     [ecx], ebx
  41 SkipEbx:
  42     pop     eax
  43     mov     ecx, RegisterEcx
  44     jecxz   SkipEcx
  45     mov     [ecx], eax
  46 SkipEcx:
  47     mov     ecx, RegisterEdx
  48     jecxz   SkipEdx
  49     mov     [ecx], edx
  50 SkipEdx:
  51     mov     eax, Index
  52   }
  53 }
  54