// Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).

 // All rights reserved.

 // This component and the accompanying materials are made available

 // under the terms of "Eclipse Public License v1.0"

 // which accompanies this distribution, and is available

 // at the URL "http://www.eclipse.org/legal/epl-v10.html".

 //

 // Initial Contributors:

 // Nokia Corporation - initial contribution.

 //

 // Contributors:

 //

 // Description:

 // wins\specific\timer.cpp

 // 

 //

 #include "variant.h"

 #define KWinsTimerPanicCategory "WinsTimer"

 enum TWinsTimerPanic

 	{

 	EReleaseSemaphoreError = 1,

 	ETimeSetEventError = 2

 	};

 void PanicFromWinsTimer(TWinsTimerPanic aReason)

 	{

 	Kern::Fault(KWinsTimerPanicCategory, aReason);

 	}

 inline Int64 FileTime2Milliseconds(const FILETIME& aFileTime)

 	{return ((Int64(aFileTime.dwHighDateTime)<<32) + aFileTime.dwLowDateTime)/10000;}

 void CALLBACK WinsTimer::Tick(UINT, UINT, DWORD aPtr, DWORD, DWORD) 

 	{

 	WinsTimer& timer=*(WinsTimer*)aPtr;

 	if (!ReleaseSemaphore(timer.iSemaphore,1,NULL))

 		{

 		__ASSERT_ALWAYS((GetLastError() == ERROR_TOO_MANY_POSTS), PanicFromWinsTimer(EReleaseSemaphoreError));

 		timeKillEvent(timer.iTimer);

 		// If WinsTimer::EventThread() has run since the above call to

 		// ReleaseSemaphore() (this has been observed to happen while 

 		// within the call to timeKillEvent()) then the semaphore may be 

 		// signallable again. If it is, restart the timer otherwise wait 

 		// for the event thread to restart it.

 		if (ReleaseSemaphore(timer.iSemaphore,1,NULL))

 			timer.Enable();

 		else

 			timer.iSuspend = timer.iMaxLagTicks;

 		}

 	}

 DWORD WINAPI WinsTimer::Thread(LPVOID aPtr)

 	{

 	static_cast<WinsTimer*>(aPtr)->EventThread(*(NTimerQ*)NTimerQ::TimerAddress());

 	return 0;

 	}

 void WinsTimer::EventThread(NTimerQ& aTimerQ)

 	{

 	for (;;)

 		{

 		WaitForSingleObject(iSemaphore,INFINITE);

 		if (iSuspend > 0)

 			{

 			// Emulator interrupted/suspended for too long, MM-callback has been suspended

 			//

 			// Rather than try and catch up now, just discard the lost ticks - this improves

 			// system behaviour particularly when debugging at the expense of losing sync

 			// between the Windows clock and the emulator RTC.

 			//

 			while (--iSuspend > 0)

 				WaitForSingleObject(iSemaphore, 0);	// absorb all signals

 			//

 			// un-nobble once we are debugging

 			if (iNobbleNanos && IsDebuggerPresent())

 				iNobbleNanos = 0;

 			//

 			// now restart the timer callbacks

 			Enable();

 			//

 			// don't deliver a tick until next callback

 			continue;

 			}

 		if (iNobbleNanos && iIdleThread != NKern::CurrentThread())

 			Kern::NanoWait(iNobbleNanos);

 		StartOfInterrupt();

 		iTime += iPeriod;

 		if (!iStandby)

 			aTimerQ.Tick();

 		EndOfInterrupt();

 		}

 	}

 WinsTimer::WinsTimer()

 	:iPeriod(0),iNobbleNanos(0),iMaxLagTicks(0),iSemaphore(NULL),iSuspend(0),iTime(0),iIdleThread(0)

 	{}

 void WinsTimer::Init(TUint aPeriod)

 	{

 	// calculate the y2k offset in seconds from Win32 'zero' FILETIME

 	// This initially synchronizes EPOC time with Windows time

 	const SYSTEMTIME KSystemTimeY2K = {2000,1,0,1,0,0,0,0};

 	FILETIME y2k, now;

 	SystemTimeToFileTime(&KSystemTimeY2K,&y2k);

 	GetSystemTimeAsFileTime(&now);

 	iTime = FileTime2Milliseconds(now) - FileTime2Milliseconds(y2k);

 	TIMECAPS caps;

 	timeGetDevCaps(&caps,sizeof(caps));

 	iPeriod = min(caps.wPeriodMax, max(caps.wPeriodMin, aPeriod));

 	TUint resolution = max(caps.wPeriodMin, iPeriod/2);

 	iMaxLagTicks = EMaxLag / iPeriod;

 	// limit 'catch-up' for when Win32 gets too busy for us to fire timer events

 	// making this too large causes delays when resuming from debug

 	iSemaphore = CreateSemaphoreA(NULL, 0, iMaxLagTicks, NULL);

 	timeBeginPeriod(resolution);

 	CreateWin32Thread(EThreadEvent, &WinsTimer::Thread, this, ETrue);

 	}

 void WinsTimer::Enable()

 	{

 	iTimer = timeSetEvent(iPeriod,0,&WinsTimer::Tick,DWORD(this),TIME_PERIODIC);

 	__ASSERT_ALWAYS(iTimer != NULL, PanicFromWinsTimer(ETimeSetEventError));

 	}

 TInt WinsTimer::SystemTime() const

 //

 // Return the time in seconds since y2k

 //

 	{

 	TInt irq = NKern::DisableAllInterrupts();

 	Int64 time = iTime;

 	NKern::RestoreInterrupts(irq);

 	if (time < 0)

 		time -= 999;	// we want rounding to -infinity for the division

 	return TInt(time/1000);

 	}

 void WinsTimer::SetSystemTime(TInt aTime)

 //

 // Set the time in seconds since y2k

 //

 	{

 	Int64 time=aTime;

 	time*=1000;

 	TInt irq = NKern::DisableAllInterrupts();

 	iTime = time;

 	NKern::RestoreInterrupts(irq);

 	}

 void WinsTimer::Standby()

 	{

 	iStandby = ETrue;

 	}

 void WinsTimer::Wakeup()

 	{

 	iStandby = EFalse;

 	// Busy wait for the next timer interrupt 

 	volatile Int64* t = &iTime;

 	Int64 time = *t;

 	while (time == *t)

 		{}

 	}