blmc/eeprom.c

/***************************************************************************
 *   Copyright (C) 02/2008 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/eeprom.h>
#include <util/crc16.h>
#include "eeprom.h"

static const struct ee_param defaults = DEFAULT_PARAMETERS;

struct ee_param params;
struct ee_param params_in_eeprom EEMEM = DEFAULT_PARAMETERS;

void write_parameters(void)
{
	uint8_t i;
	uint16_t crc = 0x0000;
	uint8_t *tmp = (uint8_t *)&params;
	for (i = 0; i < sizeof(struct ee_param) -2; i++)
		crc = _crc_ccitt_update(crc, *tmp++);

	params.crc16 = crc;
	eeprom_write_block(&params, &params_in_eeprom, sizeof(struct ee_param));
}

uint8_t read_parameters(void)
{
	eeprom_read_block(&params, &params_in_eeprom, sizeof(struct ee_param));

	uint8_t i;
	uint16_t crc = 0x0000;
	uint8_t *tmp = (uint8_t *)&params;
	for (i = 0; i < sizeof(struct ee_param); i++)
		crc = _crc_ccitt_update(crc, *tmp++);

	if (crc != 0x0000) {
		i = sizeof(struct ee_param);
		uint8_t *src = (uint8_t *)&defaults;
		uint8_t *dst = (uint8_t *)&params;
		while (i--)
			*dst++ = *src++;

		write_parameters();
		return 1;
	}
	return 0;
}