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counter.c
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counter.c
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/**
* @file counter.c
*
* @brief This file contains programming counter functions
*
* @author Thomas Fischl
* @copyright (c) 2013 Thomas Fischl
*
* 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 3 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <inttypes.h>
#include <avr/eeprom.h>
/**
* @brief Defines how often the counter value is stored in EEPROM
*/
#define COUNTER_REDUNCY 3
/**
* @brief Read current programming counter value from EEPROM
* @return Programming counter value
*/
uint16_t counter_read() {
uint16_t counter = 0xffff;
uint8_t i;
uint16_t * eeadr = 0;
for (i = 0; i < COUNTER_REDUNCY; i++) {
uint16_t eeval = eeprom_read_word(eeadr++);
if (eeval == ~eeprom_read_word(eeadr++)) {
// valid value
if (eeval < counter) counter = eeval;
}
}
return counter;
}
/**
* @brief Write given programming counter value to EEPROM
* @param counter Programming counter value
*/
void counter_write(uint16_t counter) {
uint8_t i;
uint16_t * eeadr = 0;
for (i = 0; i < COUNTER_REDUNCY; i++) {
eeprom_write_word(eeadr++, counter);
eeprom_write_word(eeadr++, ~counter);
}
}
/**
* @brief Decrement the programming counter
* @param startvalue Initial value of programming counter
*/
void counter_decrement(uint16_t startvalue) {
uint16_t counter = counter_read();
if (counter == 0xffff) counter = startvalue;
if (counter == 0) return;
counter--;
counter_write(counter);
}