git.gag.com Git - fw/altos/blob - src/util/ublox-cksum

   1 #!/usr/bin/env nickle
   2
   3 typedef struct {
   4         int     a, b;
   5 } ck_t;
   6
   7 /* Fletcher algorithm */
   8 ck_t checksum(int[] msg)
   9 {
  10         ck_t    ck = { .a = 0, .b = 0 };
  11         for (int i = 4; i < dim(msg); i++) {
  12                 ck.a += msg[i];
  13                 ck.b += ck.a;
  14                 ck.a &= 0xff;
  15                 ck.b &= 0xff;
  16         }
  17         return ck;
  18 }
  19
  20 void main()
  21 {
  22         string[...]     input;
  23         int[...]        msg;
  24
  25         setdim(input, 0);
  26         while (!File::end(stdin)) {
  27                 input[dim(input)] = gets();
  28         }
  29
  30         setdim(msg, 0);
  31         for (int i = 0; i < dim(input); i++) {
  32                 string[*] words = String::wordsplit(input[i], " ,\t");
  33                 for (int j = 0; j < dim(words); j++) {
  34                         if (words[j] == "/" + "*")
  35                                 break;
  36                         if (String::length(words[j]) > 0 &&
  37                             Ctype::isdigit(words[j][0])) {
  38                                 msg[dim(msg)] = string_to_integer(words[j]);
  39                         }
  40                  }
  41         }
  42         printf("\t0xb5, 0x62, \t\t/* length: %d bytes */\n", dim(msg));
  43         for (int i = 0; i < dim(input); i++)
  44                 printf("%s\n", input[i]);
  45         ck_t ck = checksum(msg);
  46         printf ("\t0x%02x, 0x%02x,\n",
  47                 ck.a, ck.b);
  48 }
  49
  50 main();