reactos/hal/halx86/perfcnt.c

   1 /* $Id: perfcnt.c,v 1.2 2002/09/07 15:12:10 chorns Exp $
   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 <hal.h>
  17
  18 #define NDEBUG
  19 #include <internal/debug.h>
  20
  21
  22 /* FUNCTIONS **************************************************************/
  23
  24
  25 VOID STDCALL
  26 HalCalibratePerformanceCounter(ULONG Count)
  27 {
  28    ULONG i;
  29
  30    /* save flags and disable interrupts */
  31    __asm__("pushf\n\t" \
  32            "cli\n\t");
  33
  34    for (i = 0; i < Count; i++);
  35
  36    /* restore flags */
  37    __asm__("popf\n\t");
  38 }
  39
  40
  41 LARGE_INTEGER STDCALL
  42 KeQueryPerformanceCounter(PLARGE_INTEGER PerformanceFreq)
  43 /*
  44  * FUNCTION: Queries the finest grained running count avaiable in the system
  45  * ARGUMENTS:
  46  *         PerformanceFreq (OUT) = The routine stores the number of
  47  *                                 performance counters tick per second here
  48  * RETURNS: The performance counter value in HERTZ
  49  * NOTE: Returns the system tick count or the time-stamp on the pentium
  50  */
  51 {
  52   if (PerformanceFreq != NULL)
  53     {
  54       PerformanceFreq->QuadPart = 0;
  55       return *PerformanceFreq;
  56     }
  57   else
  58     {
  59      LARGE_INTEGER Value;
  60
  61      Value.QuadPart = 0;
  62      return Value;
  63     }
  64 }
  65
  66 /* EOF */