HearItAll/CPULimiter.cpp at master · ander94lakx/HearItAll · GitHub

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#include "CPULimiter.h"

CPULimiter::CPULimiter(int p_ratio)
{
	m_ratio = p_ratio;
}

bool CPULimiter::CalculateAndSleep()
{
	// Declare variables;
	FILETIME sysidle, kerusage, userusage, threadkern
		, threaduser, threadcreat, threadexit;
	LARGE_INTEGER tmpvar, thissystime, thisthreadtime;

	// Get system kernel, user and idle times
	if (!::GetSystemTimes(&sysidle, &kerusage, &userusage))
		return false;

	// Get Thread user and kernel times
	if (!::GetThreadTimes(GetCurrentThread(), &threadcreat, &threadexit
		, &threadkern, &threaduser))
		return false;

	// Calculates total system times
	// This is sum of time used by system in kernel, user and idle mode.

	tmpvar.LowPart = sysidle.dwLowDateTime;
	tmpvar.HighPart = sysidle.dwHighDateTime;
	thissystime.QuadPart = tmpvar.QuadPart;

	tmpvar.LowPart = kerusage.dwLowDateTime;
	tmpvar.HighPart = kerusage.dwHighDateTime;
	thissystime.QuadPart = thissystime.QuadPart + tmpvar.QuadPart;

	tmpvar.LowPart = userusage.dwLowDateTime;
	tmpvar.HighPart = userusage.dwHighDateTime;
	thissystime.QuadPart = thissystime.QuadPart + tmpvar.QuadPart;

	// Calculates time spent by this thread in user and kernel mode.

	tmpvar.LowPart = threadkern.dwLowDateTime;
	tmpvar.HighPart = threadkern.dwHighDateTime;
	thisthreadtime.QuadPart = tmpvar.QuadPart;

	tmpvar.LowPart = threaduser.dwLowDateTime;
	tmpvar.HighPart = threaduser.dwHighDateTime;
	thisthreadtime.QuadPart = thisthreadtime.QuadPart + tmpvar.QuadPart;

	// Check if this is first time this function is called
	// if yes, escape rest after copying current system and thread time
	// for further use
	// Also check if the ratio of differences between current and previous times
	// exceeds the specified ratio.

	if (thisthreadtime.QuadPart != 0
		&& (((thisthreadtime.QuadPart - m_lastThreadUsageTime.QuadPart) * 100)
		- ((thissystime.QuadPart - m_lastTotalSystemTime.QuadPart)*m_ratio)) > 0)
	{
		// Calculate the time interval to sleep for averaging the extra CPU usage
		// by this thread.

		LARGE_INTEGER timetosleepin100ns;
		timetosleepin100ns.QuadPart = (((thisthreadtime.QuadPart
			- m_lastThreadUsageTime.QuadPart) * 100) / m_ratio)
			- (thissystime.QuadPart
			- m_lastTotalSystemTime.QuadPart);

		// Check if time is less than a millisecond, if yes, keep it for next time.
		if ((timetosleepin100ns.QuadPart / 10000) <= 0)
			return false;

		// Time to Sleep :)
		Sleep(timetosleepin100ns.QuadPart / 10000);
	}

	// Copy usage time values for next time calculations.
	m_lastTotalSystemTime.QuadPart = thissystime.QuadPart;
	m_lastThreadUsageTime.QuadPart = thisthreadtime.QuadPart;
	return true;
}