#include <avr/io.h>
#include <util/delay.h>
#include <util/setbaud.h>

#include "fpm.h"

#define MAXPDLEN        64
#define RST_DELAY_MS   500

#define OK            0x00

static uint8_t start_code[] = { 0xEF, 0x01 };
static uint8_t addr[] = { 0xFF, 0xFF, 0xFF, 0xFF };

static inline uint8_t read(void)
{
	while (!(UCSR0A & (1 << RXC0)))
		;
	return UDR0;
}

static inline void write(uint8_t c)
{
	while (!(UCSR0A & (1 << UDRE0)))
		;
	UDR0 = c;
}

static inline void write_bulk(uint8_t *data, uint16_t n)
{
	int i;

	for (i = 0; i < n; i++)
		write(data[i]);
}

static inline void send(uint8_t pktid, uint8_t *data, uint8_t n)
{
	int i;
	uint16_t pktlen, sum;

	write_bulk(start_code, 2);
	write_bulk(addr, 4);
	write(pktid);

	pktlen = n + 3;
	write((uint8_t)(pktlen >> 8));
	write((uint8_t)pktlen);

	sum = (pktlen >> 8) + (pktlen & 0xFF) + pktid;
	for (i = 0; i < n; i++) {
		write(data[i]);
		sum += data[i];
	}

	write((uint8_t)(sum >> 8));
	write((uint8_t)sum);
}

static inline void recv(uint8_t buf[MAXPDLEN], uint16_t *n)
{
	int i;
	uint16_t len;
	uint8_t byte;

	i = 0, len = 0;

	for (;;) {
		byte = read();
		switch (i) {
		case 0:
			if (byte != start_code[0])
				continue;
			break;
		case 1:
			if (byte != start_code[1])
				goto bad_pkt;
			break;
		case 2:
		case 3:
		case 4:
		case 5:
			// toss the address
			break;
		case 6:
			// toss the packet id
			break;
		case 7:
			len = (uint16_t)byte << 8;
			break;
		case 8:
			len |= byte;
			break;
		default:
			if ((i - 9) < MAXPDLEN) {
				buf[i - 9] = byte;
				if ((i - 8) == len) {
					*n = len;
					return;
				}
			} else {
				goto bad_pkt;
			}
			break;
		}
		i++;
	}

bad_pkt:
	*n = 0;
	return;
}

static inline uint8_t check_pwd(void)
{
	unsigned int n;
	uint8_t buf[MAXPDLEN];

	buf[0] = 0x13;
	buf[1] = (uint8_t)((uint32_t)FPM_PWD >> 24);
	buf[2] = (uint8_t)((uint32_t)FPM_PWD >> 16);
	buf[3] = (uint8_t)((uint32_t)FPM_PWD >> 8);
	buf[4] = (uint8_t)((uint32_t)FPM_PWD & 0xFF);

	send(0x01, buf, 5);
	recv(buf, &n);
	return buf[0] == OK;
}

uint8_t fpm_init(void)
{
	UBRR0H = UBRRH_VALUE;
	UBRR0L = UBRRL_VALUE;
#if USE_2X
	UCSR0A |= (1 << U2X0);
#else
	UCSR0A &= ~(1 << U2X0);
#endif
	UCSR0B = (1 << TXEN0) | (1 << RXEN0);
	UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);

	_delay_ms(RST_DELAY_MS);

	uint8_t buf[5];
	buf[0] = 0x35;
	buf[1] = 0x03;
	buf[2] = 0x00;
	buf[3] = 0x01;
	buf[4] = 0x00;
	send(0x01, buf, 5);	

	return check_pwd();
}

uint8_t fpm_getcfg(struct fpm_cfg *cfg)
{
	uint16_t n;
	uint8_t buf[MAXPDLEN];

	buf[0] = 0x0F;
	send(0x01, buf, 1);
	recv(buf, &n);

	if (buf[0] == OK && n >= 17) {
		cfg->status = ((uint16_t)buf[1] << 8) | buf[2];
		cfg->sysid = ((uint16_t)buf[3] << 8) | buf[4];
		cfg->cap = ((uint16_t)buf[5] << 8) | buf[6];
		cfg->sec_level = ((uint16_t)buf[7] << 8) | buf[8];
		cfg->addr[0] = buf[9];
		cfg->addr[1] = buf[10];
		cfg->addr[2] = buf[11];
		cfg->addr[3] = buf[12];
		cfg->pkt_size = ((uint16_t)buf[13] << 8) | buf[14];
		cfg->pkt_size = 1 << (cfg->pkt_size + 5); 
		cfg->baud = (((uint16_t)buf[15] << 8) | buf[16]);

		return 1;
	}
	return 0;
}

uint8_t fpm_setpwd(uint32_t pwd)
{
	uint16_t n;
	uint8_t buf[MAXPDLEN];

	buf[0] = 0x12;
	buf[1] = (uint8_t)(pwd >> 24);
	buf[2] = (uint8_t)(pwd >> 16);
	buf[3] = (uint8_t)(pwd >> 8);
	buf[4] = (uint8_t)(pwd & 0xFF);

	send(0x01, buf, 5);
	recv(buf, &n);
	return buf[0] == OK;
}

uint16_t fpm_get_count(void)
{
	uint16_t n, count;
	uint8_t buf[MAXPDLEN];

	buf[0] = 0x1D;
	send(0x01, buf, 1);
	recv(buf, &n);

	count = 0;
	if (buf[0] == OK && n >= 2) {
		count = buf[1];
		count <<= 8;
		count |= buf[2];
	}
	return count;
}

uint8_t fpm_enroll(void)
{
	uint16_t n, retries;
	uint8_t buf[MAXPDLEN];
	
	retries = 0;

	do {
		_delay_ms(100);
		buf[0] = 0x10;
		send(0x01, buf, 1);
		recv(buf, &n);
		retries++;
	} while (buf[0] != OK && retries < 50);
	
	return buf[0] == OK;
}

uint8_t fpm_match(void)
{
	uint16_t n, retries;
	uint8_t buf[MAXPDLEN];

	retries = 0;
	
	do {
		_delay_ms(100);
		buf[0] = 0x11;
		send(0x01, buf, 1);
		recv(buf, &n);
		retries++;
	} while (buf[0] != OK && retries < 10);

	return buf[0] == OK;
}

uint8_t fpm_delete_all(void)
{
	uint16_t n;
	uint8_t buf[MAXPDLEN];

	buf[0] = 0x0D;
	send(0x01, buf, 1);
	recv(buf, &n);
	return buf[0] == OK;
}