Ticket #12076: QPC_Check.cpp

// QPC_Check.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <stdio.h>
#include <conio.h>      // _kbhit()
#include <windows.h>    // Sleep()

// This constant is used to check for forward jumps of the performance counter
// It is dependent upon the frequency of the counter (determined via 
// QueryPerformanceFrequency() -- not used in this test app for brevity).
#define FWD_LIMIT (0x1000000)

int _tmain(int argc, _TCHAR* argv[])
{
  BOOL bDone = FALSE ;
  char cUserInput ;
  LARGE_INTEGER  liLastCount, liNewCount ;
  int nBackEventTally = 0 ;
  int nFwdEventTally = 0 ;
  
  (void)printf("QPC Check - v1.0  Hit 'c' to display current count, 'x' to exit\n") ;

  // Read counter to prime the LastCount value
  if (TRUE != QueryPerformanceCounter ( &liLastCount )) 
  {
    printf("QPC read error\n") ;
    bDone = TRUE ;
  }

  while (FALSE == bDone) 
  {
    // Respond to user input, if any
    if (0 != _kbhit()) // _kbhit() returns 0 or "non-zero"
    {
      // Get the key
      cUserInput = _getch() ;

      if (('x' == cUserInput) || ('X' == cUserInput)) 
      {
        printf("Exiting QPC_Check\n") ;
        bDone = TRUE ;
      }
      // Print status and last count
      else if (('c' == cUserInput) || ('C' == cUserInput)) 
      {
        printf("Backward events: %d   Forward events: %d", nBackEventTally, nFwdEventTally ) ;
        printf("  Last Count = 0x%08x:%08x\n", liLastCount.u.HighPart, liLastCount.u.LowPart ) ;
      }
      else if ('b' == cUserInput) 
      {
        printf("Testing backward event...\n") ;
        liLastCount.QuadPart += FWD_LIMIT ;
      }
      else if ('f' == cUserInput) 
      {
        printf("Testing forward event...\n") ;
        liLastCount.QuadPart -= (FWD_LIMIT + 1);
      }
    }

    // Read & check counter
    if (TRUE == QueryPerformanceCounter ( &liNewCount )) 
    {
      // Check for new < last
      if (liNewCount.QuadPart < liLastCount.QuadPart)
      {
        nBackEventTally++ ;
        printf("Jump backward event: Last = 0x%08x:%08x, New = 0x%08x:%08x\n", 
                liLastCount.u.HighPart, liLastCount.u.LowPart,
                liNewCount.u.HighPart,  liNewCount.u.LowPart ) ;
      }

      // Check for new >> last
      if (liNewCount.QuadPart > (liLastCount.QuadPart + FWD_LIMIT))
      {
        nFwdEventTally++ ;
        printf("Jump forward event:  Last = 0x%08x:%08x, New = 0x%08x:%08x\n", 
                liLastCount.u.HighPart, liLastCount.u.LowPart,
                liNewCount.u.HighPart,  liNewCount.u.LowPart ) ;
      }

      // Update LastCount with new value
      liLastCount.QuadPart = liNewCount.QuadPart ;
    }
    else 
    {
      printf("QPC read error\n" ) ;
      bDone = TRUE ;
    }
    Sleep( 50 ) ; // wait 50 millisecs then check counter again
  }

        return 0;
}