watrbx-game-engine/Microsoft.Xbox.Samples.NetworkMesh/Utils/Clock.h

#pragma once

#include <synchapi.h>

class Clock
{
public:
    Clock() : m_heartbeats(0), m_wakeUps(0)
    {
        m_timerFrequency.QuadPart = 0;
        m_timerStart.QuadPart = 0;
        m_countPerPeriod.QuadPart = 0;
    }

    ~Clock()
    {
    }

    void Initialize( UINT uPeriodMS )
    {
        if (!QueryPerformanceFrequency(&m_timerFrequency))
        {
            assert(false); 
        }

        SetInterval(uPeriodMS);
    }

    void SetInterval( UINT uPeriodMS )
    {
        m_countPerPeriod.QuadPart = ( m_timerFrequency.QuadPart * uPeriodMS ) / c_uOneSecondInMS;
    }

    void SleepUntilNextHeartbeat()
    {
        LARGE_INTEGER timeOfNextHeartbeat = GetNextHeartbeat();
        LARGE_INTEGER timeNow;

        m_heartbeats++; // so that the next one will be 20ms (or whatever) later...

        if (!QueryPerformanceCounter(&timeNow))
        {
            assert(false); 
        }

        LONGLONG timeDelta = timeOfNextHeartbeat.QuadPart - timeNow.QuadPart;

        if ( timeDelta > 0 )
        {
            LONGLONG numberOfMilliSecondsSinceLast = c_uOneSecondInMS * timeDelta / m_timerFrequency.QuadPart;
            WCHAR text[200] = {0};
            swprintf_s( text, L"I Slept: %lld", numberOfMilliSecondsSinceLast );
            OutputDebugString( text );
            DWORD dwSleepTime = static_cast<DWORD>(numberOfMilliSecondsSinceLast);
            Sleep( dwSleepTime );
        }
    }

    DWORD WaitForEventsOrHeartbeat(HANDLE hObject, HANDLE hObject2)
    {
        LARGE_INTEGER liExpected = GetNextHeartbeat();
        LARGE_INTEGER liNow;

        m_wakeUps = 0;
        m_heartbeats++; // so that the next one will be 20ms (or whatever) later...

        if (!QueryPerformanceCounter(&liNow))
        {
            assert(false); 
        }

        LONGLONG llDiff = liExpected.QuadPart - liNow.QuadPart;

        HANDLE aObjects[2];
        aObjects[0] = hObject;
        aObjects[1] = hObject2;

        if ( llDiff > 0 )
        {
            DWORD dwSleepTime = static_cast<DWORD>(c_uOneSecondInMS * llDiff / m_timerFrequency.QuadPart);
            m_wakeUps++;

            return ::WaitForMultipleObjectsEx( 2, aObjects, false, dwSleepTime, FALSE );
        }

        // we're already late, no need to wait, but we still need to test the object
        m_wakeUps++;
        return ::WaitForMultipleObjectsEx( 2, aObjects, false, 0, FALSE );
    }

    UINT m_wakeUps;
private:
    static const UINT c_uOneSecondInMS = 1000;
    UINT m_heartbeats;


    LARGE_INTEGER m_timerFrequency;
    LARGE_INTEGER m_timerStart;
    LARGE_INTEGER m_countPerPeriod;

    LARGE_INTEGER GetNextHeartbeat()
    {
        LARGE_INTEGER timeExpected;

        // Update Start
        if ( m_timerStart.QuadPart == 0 )
        {
            if (!QueryPerformanceCounter( &m_timerStart ))
            {
                assert(false); 
            }
            m_heartbeats = 1; // we are on the very first heartbeat
        }

        timeExpected.QuadPart = m_timerStart.QuadPart + (m_countPerPeriod.QuadPart * m_heartbeats);
        return timeExpected;
    }
};