MdePkg/Library/BaseLib/Ia32/ReadPmc.c

   1 /** @file
   2   AsmReadPmc 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
  17
  18 /**
  19   Reads the current value of a Performance Counter (PMC).
  20
  21   Reads and returns the current value of performance counter specified by
  22   Index. This function is only available on IA-32 and X64.
  23
  24   @param  Index The 32-bit Performance Counter index to read.
  25
  26   @return The value of the PMC specified by Index.
  27
  28 **/
  29 UINT64
  30 EFIAPI
  31 AsmReadPmc (
  32   IN UINT32   PmcIndex
  33   )
  34 {
  35   _asm {
  36     mov     ecx, PmcIndex
  37     rdpmc
  38   }
  39 }
  40