git.zerfleddert.de Git - fnordlicht-mini/blob - firmware/tools/fixcrc.c

   1 #include <stdio.h>
   2 #include <inttypes.h>
   3
   4 /* EEPROM data size, not including checksum */
   5 #define EEP_DATA_SIZE 494
   6 /* FIXME: actually we should either find a way to include the declaration of
   7       struct storage_t here or at least make this a command line parameter */
   8
   9 /* code from http://www.nongnu.org/avr-libc/user-manual/group__util__crc.html */
  10 uint16_t crc16_update(uint16_t crc, uint8_t a)
  11 {
  12     int i;
  13
  14     crc ^= a;
  15     for (i = 0; i < 8; ++i)
  16     {
  17         if (crc & 1)
  18             crc = (crc >> 1) ^ 0xA001;
  19         else
  20             crc = (crc >> 1);
  21     }
  22
  23     return crc;
  24 }
  25
  26 int main(int argc, char ** argv)
  27 {
  28     int i, c;
  29     uint16_t checksum = 0;
  30     for (i = 0; i < EEP_DATA_SIZE; i++) {
  31
  32         if ((c = getchar()) == EOF) {
  33             return 1;
  34         }
  35
  36         checksum = crc16_update(checksum, c);
  37
  38         if (putchar(c) == EOF) {
  39             return 2;
  40         }
  41     }
  42     putchar(checksum >> 8);
  43     putchar(checksum & 0xff);
  44
  45     return 0;
  46 }
  47