/*
 *  Copyright (C) 2002-2003  The DOSBox Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Library General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <time.h>

#include "dosbox.h"
#include "timer.h"
#include "pic.h"
#include "inout.h"
#include "mem.h"

static struct {
	Bit8u regs[0x40];
	bool nmi;
	bool bcd;
	Bit8u reg;
	struct {
		bool enabled;
		Bit8u div;
		Bitu micro;
	} timer;
	struct {
		Bit64u timer;
		Bit64u ended;
		Bit64u alarm;
	} last;
	bool ack;
	bool update_ended;
} cmos;

static void cmos_timerevent(void) {
	PIC_ActivateIRQ(8); 
	if (cmos.ack) {
		PIC_AddEvent(cmos_timerevent,cmos.timer.micro);
		cmos.regs[0x0c]|=0x0a0;
		cmos.ack=false;
	}
}

static void cmos_checktimer(void) {
	PIC_RemoveEvents(cmos_timerevent);	
	if (cmos.timer.div<=2) cmos.timer.div+=7;
	cmos.timer.micro=(Bitu) (1000000.0/(32768.0 / (1 << (cmos.timer.div - 1))));
	if (!cmos.timer.div || !cmos.timer.enabled) return;
	LOG(LOG_PIT,LOG_NORMAL)("RTC Timer at %f hz",1000000.0/cmos.timer.micro);
	PIC_AddEvent(cmos_timerevent,cmos.timer.micro);
}

void cmos_selreg(Bit32u port,Bit8u val) {
	cmos.reg=val & 0x3f;
	cmos.nmi=(val & 0x80)>0;
}

static void cmos_writereg(Bit32u port,Bit8u val) {
	switch (cmos.reg) {
	case 0x00:		/* Seconds */
	case 0x02:		/* Minutes */
	case 0x04:		/* Hours */
	case 0x06:		/* Day of week */
	case 0x07:		/* Date of month */
	case 0x08:		/* Month */
	case 0x09:		/* Year */
		/* Ignore writes to change alarm */
		break;
	case 0x01:		/* Seconds Alarm */
	case 0x03:		/* Minutes Alarm */
	case 0x05:		/* Hours Alarm */
		LOG(LOG_BIOS,LOG_NORMAL)("CMOS:Trying to set alarm");
		cmos.regs[cmos.reg]=val;
		break;

	case 0x0a:		/* Status reg A */
		cmos.regs[cmos.reg]=val & 0x7f;
		if (val & 0x70!=0x20) LOG(LOG_BIOS,LOG_ERROR)("CMOS Illegal 22 stage divider value");
		cmos.timer.div=(val & 0xf);
		cmos_checktimer();
		break;
	case 0x0b:		/* Status reg B */
		cmos.bcd=!(val & 0x4);
		cmos.regs[cmos.reg]=val & 0x7f;
		cmos.timer.enabled=(val & 0x40)>0;
		if (val&0x10) LOG(LOG_BIOS,LOG_ERROR)("CMOS:Updated ended interrupt not supported yet");
		cmos_checktimer();
		break;
	case 0x0f:		/* Shutdown status byte */
		cmos.regs[cmos.reg]=val & 0x7f;
		break;
	default:
		cmos.regs[cmos.reg]=val & 0x7f;
		LOG(LOG_BIOS,LOG_ERROR)("CMOS:WRite to unhandled register %x",cmos.reg);
	}
}


#define MAKE_RETURN(_VAL) (cmos.bcd ? (((_VAL / 10) << 4) | (_VAL % 10)) : _VAL);

static Bit8u cmos_readreg(Bit32u port) {
	if (cmos.reg>0x3f) {
		LOG(LOG_BIOS,LOG_ERROR)("CMOS:Read from illegal register %x",cmos.reg);
		return 0xff;
	}
	time_t curtime;
	struct tm *loctime;

	/* Get the current time. */
	curtime = time (NULL);

	/* Convert it to local time representation. */
	loctime = localtime (&curtime);

	switch (cmos.reg) {
	case 0x00:		/* Seconds */
		return 	MAKE_RETURN(loctime->tm_sec);
	case 0x02:		/* Minutes */
		return 	MAKE_RETURN(loctime->tm_min);
	case 0x04:		/* Hours */
		return 	MAKE_RETURN(loctime->tm_hour);
	case 0x06:		/* Day of week */
		return 	MAKE_RETURN(loctime->tm_wday);
	case 0x07:		/* Date of month */
		return 	MAKE_RETURN(loctime->tm_mday);
	case 0x08:		/* Month */
		return 	MAKE_RETURN(loctime->tm_mon);
	case 0x09:		/* Year */
		return 	MAKE_RETURN(loctime->tm_year);
	case 0x01:		/* Seconds Alarm */
	case 0x03:		/* Minutes Alarm */
	case 0x05:		/* Hours Alarm */
		return cmos.regs[cmos.reg];
	case 0x0a:		/* Status register C */
		if (PIC_Index()<0x2) {
			return (cmos.regs[0x0a]&0x7f) | 0x80;
		} else {
			return (cmos.regs[0x0a]&0x7f);
		}
	case 0x0c:		/* Status register C */
		if (cmos.timer.enabled) {
			/* In periodic interrupt mode only care for those flags */
			Bit8u val=cmos.regs[0xc];
			cmos.regs[0xc]=0;
			return val;
		} else {
			/* Give correct values at certain times */
			Bit8u val=0;
			Bit64u index=PIC_MicroCount();
			if (index>=(cmos.last.timer+cmos.timer.micro)) {
				cmos.last.timer=index;
				val|=0x40;
			} 
			if (index>=(cmos.last.ended+1000000)) {
				cmos.last.ended=index;
				val|=0x10;
			} 
			return val;
		}
	case 0x0b:		/* Status register B */
	case 0x0f:		/* Shutdown status byte */
	case 0x17:		/* Extended memory in KB Low Byte */
	case 0x18:		/* Extended memory in KB High Byte */
	case 0x30:		/* Extended memory in KB Low Byte */
	case 0x31:		/* Extended memory in KB High Byte */
		return cmos.regs[cmos.reg];
	default:
		LOG(LOG_BIOS,LOG_NORMAL)("CMOS:Read from reg %F",cmos.reg);
		return cmos.regs[cmos.reg];
	}
}

void CMOS_Init(Section* sec) {
	IO_RegisterWriteHandler(0x70,cmos_selreg,"CMOS");
	IO_RegisterWriteHandler(0x71,cmos_writereg,"CMOS");
	IO_RegisterReadHandler(0x71,cmos_readreg,"CMOS");
	cmos.timer.enabled=false;
	cmos.reg=0xa;
	cmos_writereg(0x71,0x26);
	cmos.reg=0xb;
	cmos_writereg(0x71,0);
	/* Fill in extended memory size */
	Bitu exsize=(MEM_TotalPages()*4)-1024;
	cmos.regs[0x17]=(Bit8u)exsize;
	cmos.regs[0x18]=(Bit8u)(exsize >> 8);
	cmos.regs[0x30]=(Bit8u)exsize;
	cmos.regs[0x31]=(Bit8u)(exsize >> 8);
}