//See $LK,"::/Doc/TimeDate.DD"$

U16 month_start_days[12] = {0,31,59,90,120,151,181,212,243,273,304,334};
U16 month_start_days_leap[12] = {0,31,60,91,121,152,182,213,244,274,305,335};

I64 YearStartDate(I64 year)
{//32-bit day since AD 0, given year number.
	I64 y1=year-1,yd4000=y1/4000,yd400=y1/400,yd100=y1/100,yd4=y1/4;
	return year*365+yd4-yd100+yd400-yd4000;
}

CDate Struct2Date(CDateStruct *_ds)
{//Convert CDateStruct to CDate.
	CDate cdt;
	I64 i1,i2;
	i1=YearStartDate(_ds->year);
	i2=YearStartDate(_ds->year+1);
	if (i2-i1==365)
		i1+=month_start_days[_ds->mon-1];
	else
		i1+=month_start_days_leap[_ds->mon-1];
	cdt.date=i1+_ds->day_of_mon-1;
	cdt.time=(_ds->sec10000+100*(_ds->sec100+100*(_ds->sec
				+60*(_ds->min+60*_ds->hour))))<<21/(15*15*3*625);
	return cdt;
}

I64 DayOfWeek(I64 i)
{//Day of week, given 32-bit day since AD 0.
	i+=CDATE_BASE_DAY_OF_WEEK;
	if (i>=0)
		return i % 7;
	else
		return 6-(6-i)%7;
}

U0 Date2Struct(CDateStruct *_ds,CDate cdt)
{//Convert CDate to CDateStruct.
	I64 i,k,date=cdt.date;
	_ds->day_of_week=DayOfWeek(date);
	_ds->year=(date+1)*100000/CDATE_YEAR_DAYS_INT;
	i=YearStartDate(_ds->year);
	while (i>date) {
		_ds->year--;
		i=YearStartDate(_ds->year);
	}
	date-=i;
	if (YearStartDate(_ds->year+1)-i==365) {
		k=0;
		while (date>=month_start_days[k+1] && k<11)
			k++;
		date-=month_start_days[k];
	} else {
		k=0;
		while (date>=month_start_days_leap[k+1] && k<11)
			k++;
		date-=month_start_days_leap[k];
	}
	_ds->mon=k+1;
	_ds->day_of_mon=date+1;
	k=(625*15*15*3*cdt.time)>>21+1;
	_ds->sec10000=ModU64(&k,100);
	_ds->sec100=ModU64(&k,100);
	_ds->sec=ModU64(&k,60);
	_ds->min=ModU64(&k,60);
	_ds->hour  =k;
}

I64 FirstDayOfMon(I64 i)
{//First day of month, given 32-bit day since AD 0.
	CDateStruct ds;
	CDate cdt=0;
	cdt.date=i;
	Date2Struct(&ds,cdt);
	ds.day_of_mon=1;
	cdt=Struct2Date(&ds);
	return cdt.date;
}

I64 LastDayOfMon(I64 i)
{//Last day of month, given 32-bit day since AD 0.
	CDateStruct ds;
	CDate cdt=0;
	cdt.date=i;
	Date2Struct(&ds,cdt);
	ds.mon++;
	if (ds.mon==13) {
		ds.mon=0;
		ds.year++;
	}
	ds.day_of_mon=1;
	cdt=Struct2Date(&ds);
	return cdt.date-1;
}

I64 FirstDayOfYear(I64 i)
{//First day of year, given 32-bit day since AD 0.
	CDateStruct ds;
	CDate cdt=0;
	cdt.date=i;
	Date2Struct(&ds,cdt);
	ds.day_of_mon=1;
	ds.mon=1;
	cdt=Struct2Date(&ds);
	return cdt.date;
}

I64 LastDayOfYear(I64 i)
{//Last day of year, given 32-bit day since AD 0.
	CDateStruct ds;
	CDate cdt=0;
	cdt.date=i;
	Date2Struct(&ds,cdt);
	ds.day_of_mon=1;
	ds.mon=1;
	ds.year++;
	cdt=Struct2Date(&ds);
	return cdt.date-1;
}

U8 CMOSRegRead(I64 register)
{//Read val from CMOS register. See $LK,"CMOS Registers",A="MN:CMOSR_SEC"$.
	OutU8(CMOS_SEL, register);
	return InU8(CMOS_DATA);
}

U0 CMOSRegWrite(I64 register, I64 val)
{//Write val to CMOS register. See $LK,"CMOS Registers",A="MN:CMOSR_SEC"$.
	OutU8(CMOS_SEL, register);
	OutU8(CMOS_DATA, val);
}

Bool CMOSIsBcd()
{//Check of CMOS is in binary-coded decimal mode.
// Ex: 15:32:44 == 0x15:0x32:0x44 (not good). We use $LK,"Bcd2Binary",A="MN:Bcd2Binary"$() to convert.
	return !(CMOSRegRead(CMOSR_STATUS_B) & CMOSF_BINARY);
}

I64 Bcd2Binary(U64 b)
{
	I64 i,res = 0;
	for (i = 0; i < 16; i++)
	{
		res = res * 10 + b >> 60;
		b <<= 4;
	}
	return res;
}

U0 NowDateTimeStruct(CDateStruct *_ds)
{
	I64 i;
	U8 *b = _ds;

	MemSet(_ds, 0, sizeof(CDateStruct));
	PUSHFD
	CLI
	while (LBts(&sys_semas[SEMA_SYS_DATE],0))
		PAUSE

	do {
		while (CMOSRegRead(CMOSR_STATUS_A) & CMOSF_UPDATING)
			PAUSE

		b[2] = CMOSRegRead(CMOSR_SEC);
		b[3] = CMOSRegRead(CMOSR_MIN);
		b[4] = CMOSRegRead(CMOSR_HOUR);
		b[5] = CMOSRegRead(CMOSR_DAY_OF_WEEK);
		b[6] = CMOSRegRead(CMOSR_DAY_OF_MONTH);
		b[7] = CMOSRegRead(CMOSR_MONTH);
		b[8] = CMOSRegRead(CMOSR_YEAR);

	} while (CMOSRegRead(CMOSR_STATUS_A) & CMOSF_UPDATING);

	LBtr(&sys_semas[SEMA_SYS_DATE],0);
	POPFD
	if (CMOSIsBcd)
		for (i = 2; i < 9; i++)
			b[i] = Bcd2Binary(b[i]);

	if (_ds->year > 255)			_ds->year = 255;
	_ds->year += 2000;

	if (_ds->mon > 12)				_ds->mon = 12;
	if (_ds->day_of_mon > 31) _ds->day_of_mon=31;
	if (_ds->day_of_week > 6) _ds->day_of_week=6;
	if (_ds->hour > 23) 			_ds->hour=23;
	if (_ds->min > 59)				_ds->min=59;
	if (_ds->sec > 59)				_ds->sec=59;
}

CDate Now()
{//Current datetime.
	CDateStruct ds;
	NowDateTimeStruct(&ds);
	return Struct2Date(&ds)-local_time_offset;
}

U0 TimeSet(CDateStruct *ds)
{//Set CMOS time from user crafted $LK,"CDateStruct",A="MN:CDateStruct"$.
//$BK,1$Make sure to use hex as decimals if BCD mode.$BK,0$ Check using $LK,"CMOSIsBcd",A="MN:CMOSIsBcd"$().
//Ex: if bcd mode and we want 12/30, 10:45:15 -- 0x12/0x30, 0x10:0x45:0x15.
//Pass year as double digit number (obviously 20XX is too big for a U8).
	U8 *b = ds;

	PUSHFD
	CLI
	while (LBts(&sys_semas[SEMA_SYS_DATE],0))
		PAUSE

	while (CMOSRegRead(CMOSR_STATUS_A) & CMOSF_UPDATING)
		PAUSE

	CMOSRegWrite(CMOSR_SEC, b[2]);
	CMOSRegWrite(CMOSR_MIN, b[3]);
	CMOSRegWrite(CMOSR_HOUR, b[4]);
	CMOSRegWrite(CMOSR_DAY_OF_WEEK, b[5]);
	CMOSRegWrite(CMOSR_DAY_OF_MONTH, b[6]);
	CMOSRegWrite(CMOSR_MONTH, b[7]);
	CMOSRegWrite(CMOSR_YEAR, b[8]);

	LBtr(&sys_semas[SEMA_SYS_DATE],0);
	POPFD
}