#include "hw.h"
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/eeprom.h>
#include <stdlib.h>
#include <string.h>
#include "hbw.h"

uint8_t my_address[4];

uint8_t rind;
uint16_t rcrc;
uint8_t raddress[4];
uint8_t rdest[4];
uint8_t resc;
uint8_t rctl;
volatile uint8_t rready;
uint8_t rmessage[62];
uint8_t rlen;

uint8_t sind;
uint8_t sdisc;
uint8_t sctl;
uint16_t scrc;
uint8_t sesc;
uint8_t saddress[4];
uint8_t slen;
uint8_t smessage[62];

uint16_t sdelay;

uint8_t asent;
uint8_t waitack;
uint8_t gotack;

static uint16_t crc16shift(uint16_t crc, uint8_t data)
{
        int stat, i;

        for (i=0; i<8; i++) {
                stat = crc & 0x8000;
                crc = crc << 1;
                if (data & 0x80)
                        crc = crc | 1;

                if (stat)
                        crc = crc ^ 0x1002;

                data = data << 1;
        }
        return crc;
}

static void readaddr(void)
{
	my_address[0]=eeprom_read_byte((const uint8_t *)EESIZE-4);
	my_address[1]=eeprom_read_byte((const uint8_t *)EESIZE-3);
	my_address[2]=eeprom_read_byte((const uint8_t *)EESIZE-2);
	my_address[3]=eeprom_read_byte((const uint8_t *)EESIZE-1);

	if ((my_address[0] == 0xFF) &&
	    (my_address[1] == 0xFF) &&
	    (my_address[2] == 0xFF) &&
	    (my_address[3] == 0xFF))
		my_address[0] = 0x42;
}

static void send(uint8_t i,uint8_t crc)
{
	if (bit_is_set(UCSR0A, UDRE0)) {
		if (sesc) {
			UDR0 = i & 0x7F;
			sind++;
			sesc = 0;
			return;
		}
		if (crc == 1) {
			scrc = crc16shift(scrc, i);
		}
		if (crc == 2) {
			scrc = crc16shift(scrc, 0);
			scrc = crc16shift(scrc, 0);
			i = (scrc >> 8) & 0xFF;
		}
		if ((i == 0xFD) || (i == 0xFC) || (i == 0xFE)) {
			UDR0 = 0xFC;
			sesc = 1;
			return;
		}
		UDR0 = i;
		sind++;
	}
}

void rloop(void)
{
	if (!sind)
		return;

	if (sdisc) {
		if (sind == 1) {
			send(0x04,1);
			return;
		}
		if (sind == 2) {
			send(0x01,1);
			return;
		}
		if (sind == 3) {
			send((scrc >> 8) & 0xFF,2);
			return;
		}
		if (sind == 4) {
			send(scrc & 0xFF,0);
			return;
		}
		if (bit_is_set(UCSR0A, TXC0)) {
			PORTD  &= ~(1<<SenderEnable);
			PORTD  &= ~(1<<ReceiverDisable);
			sind = 0;
			sdisc = 0;
		}
		return;
	}

	if (sind < 5) {
		send(saddress[sind-1],1);
		return;
	}
	if (sind == 5) {
		send(sctl,1);
		return;
	}
	if (sind < 10) {
		send(my_address[sind-6],1);
		return;
	}
	if (sind == 10) {
		send(slen+2,1);
		return;
	}
	if (sind < slen+10) {
		send(smessage[sind-11],1);
		return;
	}
	if (sind == slen+10) {
		send(smessage[sind-11],1);
		return;
	}
	if (sind == slen+11) {
		send((scrc >> 8) & 0xFF,2);
		return;
	}
	if (sind == slen+12) {
		send(scrc & 0xFF,0);
		return;
	}
	if (bit_is_set(UCSR0A, TXC0)) {
		PORTD  &= ~(1<<SenderEnable);
		PORTD  &= ~(1<<ReceiverDisable);
		sind = 0;
	}
}

static uint8_t sendmsg(void)
{
	if (sind)
		return 0;

	PORTD  |= (1<<SenderEnable);
	PORTD  |= (1<<ReceiverDisable);
	UCSR0A  = (1<<TXC0);

	scrc = crc16shift(0xFFFF, 0xFD);
	UDR0 = 0xFD;
	sind = 1;
	sesc = 0;
	sdisc = 0;
	return ~0;
}

static uint8_t senddsc(void)
{
	if (sind)
		return 0;

	PORTD  |= (1<<SenderEnable);
	PORTD  |= (1<<ReceiverDisable);
	UCSR0A  = (1<<TXC0);

	scrc = crc16shift(0xFFFF, 0xFE);
	UDR0 = 0xFE;
	sind = 1;
	sesc = 0;
	sdisc = 1;
	return ~0;
}

static uint8_t is_bus_free(void)
{

	if(sdelay - hbw_timer > 0x7FFF)
		return 1;
	return 0;
}

static void announce(void)
{
        sctl = 0xF8;

        saddress[0] = 0xFF;
        saddress[1] = 0xFF;
        saddress[2] = 0xFF;
        saddress[3] = 0xFF;

        slen = 16;

        smessage[0] = 0x41;
        smessage[1] = 0;
        smessage[2] = HBWTYPE;
        smessage[3] = 0;
        smessage[4] = HBWMAJOR;
        smessage[5] = HBWMINOR;
        smessage[6] = HBWSERIAL0;
        smessage[7] = HBWSERIAL1;
        smessage[8] = HBWSERIAL2;
        smessage[9] = HBWSERIAL3;
        smessage[10] = HBWSERIAL4;
        smessage[11] = HBWSERIAL5;
        smessage[12] = HBWSERIAL6;
        smessage[13] = HBWSERIAL7;
        smessage[14] = HBWSERIAL8;
        smessage[15] = HBWSERIAL9;
        sendmsg();

	asent = 1;
}

void hbw_init(void)
{
	DDRD |= (1<<SenderEnable);
	DDRD |= (1<<ReceiverDisable);

	PORTD  &= ~(1<<SenderEnable);
	PORTD  &= ~(1<<ReceiverDisable);

	UBRR0L = ((F_CPU/(BAUDRATE*16))-1) & 0xFF;
	UBRR0H = 0;
	UCSR0B = (1 << TXEN0) | (1 << RXEN0) | (1 << RXCIE0);
	UCSR0C = (1 << UPM01) | (1 << UCSZ01) | (1 << UCSZ00);

        OCR2A = 0xF9;
        TIMSK2 |= (1 << OCIE2A);
        TCCR2A |= (1 << WGM21);
        TCCR2B = TCCR2B | (1 << CS21) | (1 << CS20);

	rind = 0;
	sind = 0;
	sdisc = 0;
	rready = 0;
	asent = 0;
	hbw_timer = 0;

	readaddr();
	srand(my_address[3]);
	sdelay = 1000 + (rand() & 0x1F);
	sei();
}

static void process(void)
{
	uint8_t seq,i;
	uint16_t addr;

	if ((rdest[0] == my_address[0]) &&
	    (rdest[1] == my_address[1]) &&
	    (rdest[2] == my_address[2]) &&
	    (rdest[3] == my_address[3]) &&
	    ((rctl & 0x13) == 0x11)) {
		if (waitack) {
			waitack = 0;
			gotack = 1;
		}
		return;
	}
	if ((rdest[0] == my_address[0]) &&
	    (rdest[1] == my_address[1]) &&
	    (rdest[2] == my_address[2]) &&
	    (rdest[3] == my_address[3]) &&
	    ((rctl & 0x11) == 0x10)) {
		saddress[0] = raddress[0];
		saddress[1] = raddress[1];
		saddress[2] = raddress[2];
		saddress[3] = raddress[3];
		seq = (rctl >> 1) & 3;

		switch (rmessage[0]) {
			case '@':
				if (rmessage[1] == 'a') {
					eeprom_write_byte((uint8_t *)EESIZE-4, rmessage[2]);
					eeprom_write_byte((uint8_t *)EESIZE-3, rmessage[3]);
					eeprom_write_byte((uint8_t *)EESIZE-2, rmessage[4]);
					eeprom_write_byte((uint8_t *)EESIZE-1, rmessage[5]);

					readaddr();
				}
				slen = 0;
				sctl = 0x19 | (seq << 5);
				sendmsg();
				break;
			case 'h':
				smessage[0] = HBWTYPE;
				smessage[1] = 0;
				slen = 2;
				sctl = 0x18 | (seq << 5);
				sendmsg();
				break;
			case 'n':
				smessage[0] = HBWSERIAL0;
				smessage[1] = HBWSERIAL1;
				smessage[2] = HBWSERIAL2;
				smessage[3] = HBWSERIAL3;
				smessage[4] = HBWSERIAL4;
				smessage[5] = HBWSERIAL5;
				smessage[6] = HBWSERIAL6;
				smessage[7] = HBWSERIAL7;
				smessage[8] = HBWSERIAL8;
				smessage[9] = HBWSERIAL9;
                                slen = 10;
                                seq = (rctl >> 1) & 3;
                                sctl = 0x18 | (seq << 5);
                                sendmsg();
				break;
			case 'v':
                                smessage[0] = HBWMAJOR;
                                smessage[1] = HBWMINOR;
                                slen = 2;
                                seq = (rctl >> 1) & 3;
                                sctl = 0x18 | (seq << 5);
                                sendmsg();
				break;
			case 'R':
				addr = (rmessage[1] >> 8) | rmessage[2];
				for (i = 0; i < rmessage[3]; i++)
					smessage[i] = eeprom_read_byte((const uint8_t *)addr+i);
				slen = rmessage[3];
				seq = (rctl >> 1) & 3;
				sctl = 0x18 | (seq << 5);
				sendmsg();
				break;
			case 'W':
				addr = (rmessage[1] >> 8) | rmessage[2];
				for (i = 0; i < rmessage[3]; i++)
					eeprom_write_byte((uint8_t *)addr+i, rmessage[4+i]);
				slen = 0;
				sctl = 0x19 | (seq << 5);
				sendmsg();
				break;
			case 'x':
			case 's':
				hbw_set_channel(rmessage[1], rlen - 2, &(rmessage[2]));
			case 'S':
				smessage[0] = 'i';
				smessage[1] = rmessage[1];
				slen = hbw_get_channel(rmessage[1], &(smessage[2])) + 2;
				seq = (rctl >> 1) & 3;
				sctl = 0x18 | (seq << 5);
				sendmsg();
				break;
			case 'C':
				slen = 0;
				sctl = 0x19 | (seq << 5);
				sendmsg();
				break;
		}
	}
}

void hbw_loop(void)
{
	rloop();
	if (rready) {
		process();
		rready = 0;
	}
	if (!asent) {
		if (is_bus_free()) {
			announce();
		}
	}
}

uint8_t hbw_send_channel(uint8_t channel, uint8_t length, uint8_t const * const data, uint32_t target_address)
{
	if (gotack) {
		gotack = 0;
		return 1;
	}

	if (!is_bus_free())
		return 0;

	if (waitack)
		return 0;

	slen = length + 2;
	sctl = 0xF8;
	saddress[0] = eeprom_read_byte((const uint8_t *)2);
	saddress[1] = eeprom_read_byte((const uint8_t *)3);
	saddress[2] = eeprom_read_byte((const uint8_t *)4);
	saddress[3] = eeprom_read_byte((const uint8_t *)5);
	smessage[0] = 'i';
	smessage[1] = channel;
	memcpy(&(smessage[2]), data, length);
	sendmsg();
	waitack = 1;
	gotack = 0;
	return 0;
}

ISR(USART_RX_vect)
{
	uint8_t c;

	sdelay = hbw_timer + 100 + (rand() & 0x1F);

	c = UDR0;
	if (c == 0xFE) {
		rind = 255;
		resc = 0;
	}
	if (c == 0xFD) {
		rind = 0;
		resc = 0;
		rready = 0;
		rcrc =0xFFFF;
	}
	if (rind < 255) {
		if (c == 0xFC) {
			resc = 1;
			return;
		}
		if (resc)
			c = c | 0x80;
		rcrc = crc16shift(rcrc, c);
		resc = 0;
		rind++;
	}
	if ((rind == 1) || (rind == 255))
		return;
	if (rind < 6) {
		rdest[rind-2] = c;
		return;
	}
	if (rind == 6) {
		rctl = c;
		return;
	}
	if (rind < 11) {
		raddress[rind-7] = c;
		return;
	}
	if (rind == 11) {
		rlen = c;
		return;
	}
	if ((rlen < 2) || (rlen > 64)) {
		rind = 255;
		return;
	}
	if ((rind < rlen + 10)) {
		rmessage[rind-12] = c;
		return;
	}
	if (rind == rlen + 10)
		return;
	if (rind == rlen + 11) {
		rind = 255;
		if (rcrc)
			return;
		rready = 1;
		return;
	}
}


ISR(TIMER2_COMPA_vect)
{
	cli();
	hbw_timer++;
	sei();
}