example use of QueryPerformanceCounter

gistfile1.txt

long double PCFreqMillis = 0.0;

// this call only needed once...
// who knows if this is useful or not, speed-wise...
void WarmupCounter()
{
    LARGE_INTEGER li;
	BOOL ret = QueryPerformanceFrequency(&li);
	assert(ret != 0); // only gets run in debug mode LODO
    PCFreqMillis = (long double(li.QuadPart))/1000.0;
}

__int64 StartCounter()
{
    LARGE_INTEGER li;
    QueryPerformanceCounter(&li);
    return (__int64) li.QuadPart;
}

long double GetCounterSinceStartMillis(__int64 sinceThisTime)
{
    LARGE_INTEGER li;
    QueryPerformanceCounter(&li);
	assert(PCFreq!= 0.0);
    return long double(li.QuadPart-sinceThisTime)/PCFreqMillis; //division kind of forces us to return a double of some sort...
} // LODO do I really need long double here? no really.
// use like 
// 	__int64 start = StartCounter();
// ...
// long double elapsed = GetCounterSinceStartMillis(start)
// printf("took %.020Lf ms", elapsed);
// or to deeply debug: printf("start %I64d end %I64d took %.020Lf ms", start, StartCounter(), elapsed);