// 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)

		{}

	}