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 UINT32
  16 EFIAPI
  17 AsmCpuid (
  18   IN      UINT32                    Index,
  19   OUT     UINT32                    *RegisterEax,  OPTIONAL
  20   OUT     UINT32                    *RegisterEbx,  OPTIONAL
  21   OUT     UINT32                    *RegisterEcx,  OPTIONAL
  22   OUT     UINT32                    *RegisterEdx   OPTIONAL
  23   )
  24 {
  25   _asm {
  26     mov     eax, Index
  27     cpuid
  28     push    ecx
  29     mov     ecx, RegisterEax
  30     jecxz   SkipEax
  31     mov     [ecx], eax
  32 SkipEax:
  33     mov     ecx, RegisterEbx
  34     jecxz   SkipEbx
  35     mov     [ecx], ebx
  36 SkipEbx:
  37     pop     eax
  38     mov     ecx, RegisterEcx
  39     jecxz   SkipEcx
  40     mov     [ecx], eax
  41 SkipEcx:
  42     mov     ecx, RegisterEdx
  43     jecxz   SkipEdx
  44     mov     [ecx], edx
  45 SkipEdx:
  46     mov     eax, Index
  47   }
  48 }
  49