class HRTimer {
public:
    HRTimer(void) {
        frequency = this->GetFrequency();
    }
    LARGE_INTEGER getFrequency() {
        LARGE_INTEGER proc_freq;
        QueryPerformanceFrequency(&proc_freq);
        return proc_freq.QuadPart;
    }
    void startTimer() {
        DWORD_PTR oldmask = ::SetThreadAffinityMask(::GetCurrentThread(), 0);
        ::QueryPerformanceCounter(&start);
        ::SetThreadAffinityMask(::GetCurrentThread(), oldmask);
    }
    double stopTimer() {
        DWORD_PTR oldmask = ::SetThreadAffinityMask(::GetCurrentThread(), 0);
        ::QueryPerformanceCounter(&stop);
        ::SetThreadAffinityMask(::GetCurrentThread(), oldmask);
        return ((stop.QuadPart - start.QuadPart) / (double)frequency);
    }
private:
    LARGE_INTEGER start;
    LARGE_INTEGER stop;
    LARGE_INTEGER frequency;
}