fix byte sex

[fnordlicht-mini] / firmware / tools / fixcrc.c

#include <stdio.h>
#include <inttypes.h>

/* EEPROM data size, not including checksum */
#define EEP_DATA_SIZE 494
/* FIXME: actually we should either find a way to include the declaration of
      struct storage_t here or at least make this a command line parameter */

/* code from http://www.nongnu.org/avr-libc/user-manual/group__util__crc.html */
uint16_t crc16_update(uint16_t crc, uint8_t a)
{
    int i;

    crc ^= a;
    for (i = 0; i < 8; ++i)
    {
        if (crc & 1)
            crc = (crc >> 1) ^ 0xA001;
        else
            crc = (crc >> 1);
    }

    return crc;
}

int main(int argc, char ** argv)
{
    int i, c;
    uint16_t checksum = 0;
    for (i = 0; i < EEP_DATA_SIZE; i++) {

        if ((c = getchar()) == EOF) {
            return 1;
        }

        checksum = crc16_update(checksum, c);

        if (putchar(c) == EOF) {
            return 2;
        }
    }
    putchar(checksum & 0xff);
    putchar(checksum >> 8);

    return 0;
}