U0 PortNop()
{//Innoculous (reads IRQ Mask) which should take fixed time
//because it's an ISA-bus standard.  It takes 1.0uS-2.0uS.
	InU8(0x21);
}

U0 IntCore0TimerHandler(CTask *)
{//Called from $LK,"IntCore0TimerHandler",A="FF:::/Kernel/KInterrupts.CC,IntCore0TimerHandler"$
	I64 i;
	if (mp_count>1)
		while (LBts(&sys_semas[SEMA_SYS_TIMER],0))
			PAUSE
	lock counts.jiffies++;
	counts.timer+=SYS_TIMER0_PERIOD+1;
	LBtr(&sys_semas[SEMA_SYS_TIMER],0);
	for (i=1;i<mp_count;i++)
		MPInt(I_TIMER,i);
	OutU8(PIC1,PIC_EOI); //Acknowledge PIC Interrupt
}

I64 SysTimerRead()
{//System timer count with overflow already handled.
	I64 i,res;
	PUSHFD
	CLI
	if (mp_count > 1)
		while (LBts(&sys_semas[SEMA_SYS_TIMER],0))
			PAUSE
	OutU8(PIT_CMD, PIT_CMDF_CHANNEL0); //Latch Timer0
	if ((i=InU8(PIT0) + InU8(PIT0) << 8) == SYS_TIMER0_PERIOD)
	{
		if (InU8(PIC1) & 1)
			i=-1;
	}
	res=counts.timer+SYS_TIMER0_PERIOD-i;
	LBtr(&sys_semas[SEMA_SYS_TIMER],0);
	POPFD
	return res;
}

I64 TimeCal()
{
	static I64 time_stamp_start=0,timer_start=0;
	I64 i;
	if (time_stamp_start)
	{
		PUSHFD
		CLI
			counts.time_stamp_freq = SYS_TIMER_FREQ * (GetTSC - time_stamp_start);
			i = SysTimerRead - timer_start;
		if (!i)
			ZenithErr("Timer Cal Error");
		else
		{
			counts.time_stamp_freq/=i;
			counts.time_stamp_kHz_freq=counts.time_stamp_freq/1000;
			counts.time_stamp_calibrated=TRUE;
		}
		POPFD
	}
	PUSHFD
	CLI
	timer_start = SysTimerRead;
	time_stamp_start = GetTSC;
	POPFD
	return counts.time_stamp_freq;
}

F64 tS()
{//Time since boot in seconds as a float.
	return SysTimerRead/ToF64(SYS_TIMER_FREQ);
}

Bool Blink(F64 Hz=2.5)
{//Return TRUE, then FALSE, then TRUE at given frequency.
	if (!Hz) return 0;
	return ToI64(counts.jiffies*2*Hz/JIFFY_FREQ)&1;
}

U0 Busy(I64 ęS)
{//Loosely timed.
	I64 i;
	for (i=0;i<ęS;i++)
		PortNop;
}

U0 SleepUntil(I64 wake_jiffy)
{//Not for power-saving.It is to make a program pause without hogging the CPU.
	Bool old_idle=LBts(&Fs->task_flags,TASKf_IDLE);
	Fs->wake_jiffy=wake_jiffy;
	Yield;
	LBEqual(&Fs->task_flags,TASKf_IDLE,old_idle);
}

U0 Sleep(I64 mS)
{//Not for power-saving.It is to make a program pause without hogging the CPU.
	if (!mS)
		Yield;
	else
		SleepUntil(counts.jiffies+mS*JIFFY_FREQ/1000);
}

F64 Ona2Freq(I8 ona)
{//Ona to freq. Ona=60 is 432.0Hz.
	if (!ona)
		return 0;
	else
		return 432.0/32*2.0`(ona/12.0);
}

I8 Freq2Ona(F64 freq)
{//Freq to Ona. 432.0Hz is Ona=60.
	if (freq>0)
		return ClampI64(12*Log2(32.0/432.0*freq),1,I8_MAX);
	else
		return 0;
}

U0 Sound(I8 ona=0)
{//Play ona, a piano key num. 0 means rest.
	I64 period;
	CSoundData *d;
	if (!Bt(&sys_semas[SEMA_MUTE],0) && !LBts(&sys_semas[SEMA_SOUND],0))
	{ //Mutex. Just throw-out if in use
		if (!ona)
		{
			screencast.ona=ona;
			OutU8(PCSPKR, InU8(PCSPKR) & ~3);
		}
		else if (ona!=screencast.ona)
		{
			screencast.ona=ona;
			period=ClampI64(SYS_TIMER_FREQ/Ona2Freq(ona),1,U16_MAX);
			//See $LK,"::/Doc/PIT.DD",A="FI:::/Doc/PIT.DD"$.
			OutU8(PIT_CMD,PIT_CMDF_CHANNEL2 | PIT_CMDF_OPMODE_SQUARE_WAVE | PIT_CMDF_ACCESS_WORD);
			OutU8(PIT2,period);
			OutU8(PIT2,period.u8[1]);
			OutU8(PCSPKR,3|InU8(PCSPKR)); //enable speaker
		}
		if (!IsDebugMode && screencast.record)
		{
			d=ZCAlloc(sizeof(CSoundData));
			d->ona=ona;
			d->tS=tS;
			QueueInsert(d,screencast.sound_head.last);
		}
		LBtr(&sys_semas[SEMA_SOUND],0);
	}
}

Bool ScreenCast(Bool val=ON,Bool just_audio=FALSE,U8 *print_format="B:/Tmp/%X.GR")
{//WinMgr saves GR files to a dir.
	Bool old_val;
	screencast.just_audio=just_audio;
	if (val) {
		if (!(old_val=LBtr(&screencast.record,0))) {
			Free(screencast.print_format);
			screencast.print_format=ZStrNew(print_format);
			screencast.t0_now=Now;
			screencast.sound_head.tS=screencast.t0_tS=tS;
			screencast.sound_head.ona=screencast.ona;
			LBts(&screencast.record,0);
		}
	} else
		old_val=LBtr(&screencast.record,0);
	Sound;
	return old_val;
}

U0 SoundReset()
{//Fix stuck sound.
	if (Bt(&sys_semas[SEMA_SOUND],0)) {
		Sleep(1);
		if (Bt(&sys_semas[SEMA_SOUND],0)) {
			Sleep(1);
			LBtr(&sys_semas[SEMA_SOUND],0);
		}
	}
	Sound;
}

U0 Beep(I8 ona=62,Bool busy=FALSE)
{//Make beep at given ona freq.
	Sound(ona);
	if (busy)
		Busy(500000);
	else
		Sleep(500);
	Sound;
	if (busy)
		Busy(200000);
	else
		Sleep(200);
}

Bool Mute(Bool val)
{//Turn-off sound.
	Bool res;
	if (val) {
		PUSHFD
		CLI
		Sound;
		res=LBts(&sys_semas[SEMA_MUTE],0);
		POPFD
	} else
		res=LBtr(&sys_semas[SEMA_MUTE],0);
	return res;
}

Bool IsMute()
{//Return is-mute flag.
	return Bt(&sys_semas[SEMA_MUTE],0);
}

Bool Silent(Bool val=ON)
{//Turn-off StdOut console text. (Not sound.)
	return LBEqual(&Fs->display_flags,DISPLAYf_SILENT,val);
}

Bool IsSilent()
{//Return StdOut turned-off?
	return Bt(&Fs->display_flags,DISPLAYf_SILENT);
}

Bool SysDebug(Bool val)
{//Set SysDebug bit you can use while debugging.
	return LBEqual(&sys_semas[SEMA_DEBUG],0,val);
}

Bool IsSysDebug()
{//Return SysDebug bit.
	return Bt(&sys_semas[SEMA_DEBUG],0);
}

Bool Raw(Bool val)
{//Set to direct screen, BLACK & WHITE, non-windowed output mode.
	if (!val)
		VBEFlush;
	return !LBEqual(&Fs->display_flags,DISPLAYf_NOT_RAW,!val);
}

Bool IsRaw()
{//Are we in BLACK & WHITE raw screen mode?
	return !Bt(&Fs->display_flags,DISPLAYf_NOT_RAW);
}

Bool SingleUser(Bool val)
{//Set single-user mode.
	return LBEqual(&sys_semas[SEMA_SINGLE_USER],0,val);
}

Bool IsSingleUser()
{//Return single-user mode.
	return Bt(&sys_semas[SEMA_SINGLE_USER],0);
}

Bool DebugMode(Bool val)
{//Set debug-mode.
	return LBEqual(&sys_semas[SEMA_DEBUG_MODE],0,val);
}

Bool IsDebugMode()
{//Return debug-mode.
	return Bt(&sys_semas[SEMA_DEBUG_MODE],0);
}

U0 ProgressBarsReset(U8 *path=NULL)
{//Reset all progress bars to zero.
	CallExtStr("ProgressBarsRegTf",path);
	MemSet(sys_progresses,0,sizeof(sys_progresses));
}