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// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
#include "precomp.h"
static BOOL vfHighPerformanceCounter = TRUE; // assume the system has a high performance counter
static double vdFrequency = 1;
/********************************************************************
PerfInitialize - initializes internal static variables
********************************************************************/
extern "C" void DAPI PerfInitialize(
)
{
LARGE_INTEGER liFrequency = { };
//
// check for high perf counter
//
if (!::QueryPerformanceFrequency(&liFrequency))
{
vfHighPerformanceCounter = FALSE;
vdFrequency = 1000; // ticks are measured in milliseconds
}
else
vdFrequency = static_cast<double>(liFrequency.QuadPart);
}
/********************************************************************
PerfClickTime - resets the clicker, or returns elapsed time since last call
NOTE: if pliElapsed is NULL, resets the elapsed time
if pliElapsed is not NULL, returns perf number since last call to PerfClickTime()
********************************************************************/
extern "C" void DAPI PerfClickTime(
__out_opt LARGE_INTEGER* pliElapsed
)
{
static LARGE_INTEGER liStart = { };
LARGE_INTEGER* pli = pliElapsed;
if (!pli) // if elapsed time time was not requested, reset the start time
pli = &liStart;
if (vfHighPerformanceCounter)
::QueryPerformanceCounter(pli);
else
pli->QuadPart = ::GetTickCount();
if (pliElapsed)
pliElapsed->QuadPart -= liStart.QuadPart;
}
/********************************************************************
PerfConvertToSeconds - converts perf number to seconds
********************************************************************/
extern "C" double DAPI PerfConvertToSeconds(
__in const LARGE_INTEGER* pli
)
{
Assert(0 < vdFrequency);
return pli->QuadPart / vdFrequency;
}
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