Source code of Windows XP (NT5)
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2.3 KiB

//+------------------------------------------------------------------------
//
// Microsoft Windows
// Copyright (C) Microsoft Corporation, 1993.
//
// File: stopwtch.cxx
//
// Contents: StopWatch timer
//
// Classes: CStopWatch
//
// Functions:
//
// History: 30-June-93 t-martig Created
//
//--------------------------------------------------------------------------
extern "C"
{
#include <nt.h>
#include <ntrtl.h>
#include <nturtl.h>
};
#include <windows.h>
#include <stopwtch.hxx>
//+-------------------------------------------------------------------
//
// Member: CStopWatch::Resolution, public
//
// Synopsis: Inquires performance timer resolution
//
// Returns: Performance counter ticks / second
//
// History: 30-June-93 t-martig Created
//
//--------------------------------------------------------------------
CStopWatch::CStopWatch ()
{
QueryPerformanceFrequency (&liFreq);
}
//+-------------------------------------------------------------------
//
// Member: CStopWatch::Reset, public
//
// Synopsis: Starts measurement cycle
//
// History: 30-June-93 t-martig Created
//
//--------------------------------------------------------------------
void CStopWatch::Reset ()
{
QueryPerformanceCounter (&liStart); // BUGBUG - test for error !
}
//+-------------------------------------------------------------------
//
// Member: CStopWatch::Read, public
//
// Synopsis: Reads stop watch timer
//
// Returns: Time since call of CStopWatch::Reset (in microseconds)
//
// History: 30-June-93 t-martig Created
//
//--------------------------------------------------------------------
ULONG CStopWatch::Read ()
{
LARGE_INTEGER liNow, liDelta, liRemainder;
QueryPerformanceCounter (&liNow); // BUGBUG - test for error
liDelta = RtlLargeIntegerSubtract (liNow, liStart);
liDelta = RtlExtendedIntegerMultiply (liDelta, 1000000);
liDelta = RtlLargeIntegerDivide (liDelta, liFreq, &liRemainder);
return liDelta.LowPart;
}
//+-------------------------------------------------------------------
//
// Member: CStopWatch::Resolution, public
//
// Synopsis: Inquires performance timer resolution
//
// Returns: Performance counter ticks / second
//
// History: 30-June-93 t-martig Created
//
//--------------------------------------------------------------------
ULONG CStopWatch::Resolution ()
{
return liFreq.LowPart;
}