MdePkg/Library/BaseLib/Ia32/ReadPmc.c

   1 /** @file
   2   AsmReadPmc 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   Reads the current value of a Performance Counter (PMC).
  17
  18   Reads and returns the current value of performance counter specified by
  19   Index. This function is only available on IA-32 and X64.
  20
  21   @param  Index The 32-bit Performance Counter index to read.
  22
  23   @return The value of the PMC specified by Index.
  24
  25 **/
  26 UINT64
  27 EFIAPI
  28 AsmReadPmc (
  29   IN UINT32   Index
  30   )
  31 {
  32   _asm {
  33     mov     ecx, Index
  34     rdpmc
  35   }
  36 }
  37