HighPrecisionTime.hxx

#pragma once
#include <Windows.h>

class HighPrecisionTime
{
	LARGE_INTEGER m_freq;

	FILETIME m_lastTime;
	LARGE_INTEGER m_lastCount;

public:
	static const unsigned long ONE_HUNDRED_NANOSECS_PER_SEC = 10 * 1000 * 1000;

	HighPrecisionTime()
	{
		if (!::QueryPerformanceFrequency(&m_freq))
		{
			m_freq.QuadPart = 0;
		}
	}

	bool IsAvailabe() const
	{
		return m_freq.QuadPart != 0;
	}

	// system tick of 100-nanosecond intervals
	LONGLONG GetNanoTime()
	{
		if (!IsAvailabe()) return 0;

		LARGE_INTEGER count;
		if (::QueryPerformanceCounter(&count))
		{
			return (count.QuadPart * ONE_HUNDRED_NANOSECS_PER_SEC) / m_freq.QuadPart;
		}
		return 0;
	}

	bool GetCurrentAsFileTime(LPFILETIME lpSystemTimeAsFiletime)
	{
		::GetSystemTimeAsFileTime(lpSystemTimeAsFiletime);

		if (memcmp(lpSystemTimeAsFiletime, &m_lastTime, sizeof(FILETIME)) != 0)
		{
			::QueryPerformanceCounter(&m_lastCount);
			m_lastTime = *lpSystemTimeAsFiletime;
			return true;
		}

		LARGE_INTEGER count;
		if (::QueryPerformanceCounter(&count))
		{
			LONGLONG countdiff = count.QuadPart - m_lastCount.QuadPart;
			LONGLONG nanosecdiff = (countdiff * ONE_HUNDRED_NANOSECS_PER_SEC) / m_freq.QuadPart;

			ULARGE_INTEGER tmp = { lpSystemTimeAsFiletime->dwLowDateTime, lpSystemTimeAsFiletime->dwHighDateTime };
			tmp.QuadPart += nanosecdiff;
			lpSystemTimeAsFiletime->dwLowDateTime = tmp.LowPart;
			lpSystemTimeAsFiletime->dwHighDateTime = tmp.HighPart;

			return true;
		}

		return false;
	}

	bool GetCurrentLocalTime(LPSYSTEMTIME lpLocalTime, const TIME_ZONE_INFORMATION* lpTimezoneInfo = NULL)
	{
		SYSTEMTIME sysTime;
		return GetCurrentSystemTime(&sysTime) && ::SystemTimeToTzSpecificLocalTime(lpTimezoneInfo, &sysTime, lpLocalTime);
	}

	bool GetCurrentSystemTime(LPSYSTEMTIME lpSysTime)
	{
		FILETIME filetime;
		return GetCurrentAsFileTime(&filetime) && ::FileTimeToSystemTime(&filetime, lpSysTime) != 0;
	}
};