tools/firmware-utils/src/mkdcs932.c

   1 /*
   2  * This program is free software; you can redistribute it and/or
   3  * modify it under the terms of the GNU General Public License,
   4  * version 2 as published by the Free Software Foundation.
   5  *
   6  * (C) John Crispin <blogic@openwrt.org>
   7  */
   8
   9 #include <sys/types.h>
  10 #include <sys/stat.h>
  11 #include <fcntl.h>
  12 #include <stdio.h>
  13 #include <stdint.h>
  14 #include <unistd.h>
  15 #include <errno.h>
  16
  17 int main(int argc, char **argv)
  18 {
  19         uint32_t t = 0, sum = 0x55aa55aa;
  20         int fd;
  21
  22         if ((argc != 2) || ((fd = open(argv[1], O_RDWR)) == -1)) {
  23                 fprintf(stderr, "Usage: %s input_file\n", *argv);
  24                 return -EINVAL;
  25         }
  26
  27         lseek(fd, -4, SEEK_END);
  28         write(fd, &t, 4);
  29         lseek(fd, 0, SEEK_SET);
  30
  31         while (read(fd, &t, 4) > 0)
  32                 sum -= t;
  33
  34         lseek(fd, -4, SEEK_END);
  35         write(fd, &sum, 4);
  36         close(fd);
  37
  38         return 0;
  39 }