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

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <inttypes.h>
   4
   5 /* EEPROM data size, not including checksum */
   6 #define EEP_DATA_SIZE 494
   7 /* FIXME: actually we should either find a way to include the declaration of
   8       struct storage_t here or at least make this a command line parameter */
   9
  10 /* code from http://www.nongnu.org/avr-libc/user-manual/group__util__crc.html */
  11 uint16_t crc16_update(uint16_t crc, uint8_t a)
  12 {
  13     int i;
  14
  15     crc ^= a;
  16     for (i = 0; i < 8; ++i)
  17     {
  18         if (crc & 1)
  19             crc = (crc >> 1) ^ 0xA001;
  20         else
  21             crc = (crc >> 1);
  22     }
  23
  24     return crc;
  25 }
  26
  27 /* oh, this is soooo ugly... :-( */
  28 int main(int argc, char ** argv)
  29 {
  30     int i, c, id;
  31     uint16_t checksum = 0;
  32
  33     if ((argc < 2) || ((id = atoi(argv[1])) > 15) || (id <= 0))
  34     {
  35         fputs("usage: patcheeprom id < eeprom-template > eeprom-binary\n\n", stderr);
  36         return 127;
  37     }
  38     /* print out magic byte and add it to checksum */
  39     putchar(0x23);
  40     checksum = crc16_update(checksum, 0x23);
  41
  42     /* print out id and add it to checksum */
  43     putchar(id);
  44     checksum = crc16_update(checksum, id);
  45
  46     /* ignore first two bytes of input */
  47     getchar();
  48     getchar();
  49
  50     /* now copy template and adapt checksum */
  51     for (i = 2; i < EEP_DATA_SIZE; i++) {
  52
  53         if ((c = getchar()) == EOF) {
  54             return 1;
  55         }
  56
  57         checksum = crc16_update(checksum, c);
  58
  59         if (putchar(c) == EOF) {
  60             return 2;
  61         }
  62     }
  63     /* print out checksum, and we're done */
  64     putchar(checksum & 0xff);
  65     putchar(checksum >> 8);
  66
  67     return 0;
  68 }
  69