hal/halx86/perfcnt.c

   1 /* $Id$
   2  *
   3  * COPYRIGHT:      See COPYING in the top level directory
   4  * PROJECT:        ReactOS kernel
   5  * FILE:           ntoskrnl/hal/x86/perfcnt.c
   6  * PURPOSE:        Performance counter functions
   7  * PROGRAMMER:     David Welch (welch@mcmail.com)
   8  *                 Eric Kohl (ekohl@rz-online.de)
   9  * UPDATE HISTORY:
  10  *                 09/06/2000: Created
  11  */
  12
  13
  14 /* INCLUDES ***************************************************************/
  15
  16 #include <ddk/ntddk.h>
  17
  18 /* FUNCTIONS **************************************************************/
  19
  20
  21 VOID STDCALL
  22 HalCalibratePerformanceCounter(ULONG Count)
  23 {
  24    ULONG i;
  25
  26    /* save flags and disable interrupts */
  27    __asm__("pushf\n\t" \
  28            "cli\n\t");
  29
  30    for (i = 0; i < Count; i++);
  31
  32    /* restore flags */
  33    __asm__("popf\n\t");
  34 }
  35
  36
  37 LARGE_INTEGER STDCALL
  38 KeQueryPerformanceCounter(PLARGE_INTEGER PerformanceFreq)
  39 /*
  40  * FUNCTION: Queries the finest grained running count avaiable in the system
  41  * ARGUMENTS:
  42  *         PerformanceFreq (OUT) = The routine stores the number of
  43  *                                 performance counters tick per second here
  44  * RETURNS: The performance counter value in HERTZ
  45  * NOTE: Returns the system tick count or the time-stamp on the pentium
  46  */
  47 {
  48   if (PerformanceFreq != NULL)
  49     {
  50       PerformanceFreq->QuadPart = 0;
  51       return *PerformanceFreq;
  52     }
  53   else
  54     {
  55      LARGE_INTEGER Value;
  56
  57      Value.QuadPart = 0;
  58      return Value;
  59     }
  60 }
  61
  62 /* EOF */