/***************************************************************************
 *   Copyright (C) 03/2010 by Olaf Rempel                                  *
 *   razzor@kopf-tisch.de                                                  *
 *                                                                         *
 *   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; version 2 of the License,               *
 *                                                                         *
 *   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 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 <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>

#define F_CPU 8000000
#include <util/delay.h>

#include "6x8_vertikal_LSB_1.h"

#define nop() asm volatile ("nop")

#define nCLEAR	PB0
#define RCLK	PB1
#define nOE	PB2
#define MOSI	PB3
#define MISO	PB3
#define SCK	PB5

#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))

static const char text[] = "    <<<atmega168:Scrolltext-Demo>>>  ";

/* scrollbuffer */
static volatile uint8_t data[32];
static volatile uint8_t offset;

void setRow(uint8_t row)
{
	uint8_t i;
	volatile uint8_t *p = data + offset + 19;

	row = (1 << row);

	/* bit-banging spi, 20 cols */
	for (i = 0; i < 20; i++) {
		PORTB &= ~(1<<MISO);
		if (*p-- & row)
			PORTB |= (1<<MOSI);

		PORTB |= (1<<SCK);
		PORTB &= ~(1<<SCK);

		/* insert extra cols (unused hc595 outputs) */
		if (i == 5 || i == 12 || i == 19) {
			PORTB |= (1<<SCK);
			PORTB &= ~(1<<SCK);
		}
	}

	/* disable outputs, update register */
	PORTB |= ((1<<nOE) | (1<<RCLK));

	/* select row */
	PORTC |= 0x07;
	PORTC &= ~(row & 0x07);
	PORTD |= 0x78;
	PORTD &= ~(row & 0x78);

	/* enable outputs again */
	PORTB &= ~((1<<nOE) | (1<<RCLK));
}

ISR(SIG_OVERFLOW0)
{
	static uint8_t row;

	/* 2ms */
	TCNT0 = 0xFF - 64;

	setRow(row++);
	if (row == 7)
		row = 0;
}

int main(void)
{
	/* row 1-3 */
	DDRC  = 0x07;
	PORTC = 0x07;

	/* row 4-7 */
	DDRD  = 0x78;
	PORTD = 0x78;

	/* ctrl signals */
	DDRB  = (1<<nCLEAR) | (1<<RCLK) | (1<<nOE) | (1<<MOSI) | (1<<SCK);
	PORTB = (1<<nCLEAR) | (1<<nOE);

	/* F_CPU/256, Overflow Interrupt */
	TCCR0B = (1<<CS02);
	TIMSK0 = (1<<TOIE0);

	sei();

	uint8_t mode = 0;
	uint8_t pos = 0;
	uint8_t delay = 0;

	while (1) {
		switch (mode)
		{
		case 0:
			if (offset == 6) {
				offset = 0;
				if (text[pos +3] == '\0') {
					pos = 0;
					mode++;

				} else {
					pos++;
				}
			}

			if (offset == 0) {
				int i;
				for (i = 0; i < 5; i++) {
					memcpy_P((void *)&data[i * 6], font[(uint8_t)text[pos + i]], 5);
				}
			}

			offset++;
			delay = 6;
			break;

		case 1:
			if (offset == 6) {
				offset = 0;
				if (pos == (ARRAY_SIZE(font) -3)) {
					pos = 0;
					mode++;

				} else {
					pos++;
				}
			}

			if (offset == 0) {
				int i;
				for (i = 0; i < 5; i++) {
					memcpy_P((void *)&data[i * 6], font[(uint8_t)pos + i], 5);
				}
			}

			offset++;
			delay = 6;
			break;

		default:
			mode = 0;
			delay = 0;
			break;
		}

		while (delay--)
			_delay_ms(10);
	}

	return 0;
}