zelda-cksum.c

   1 // Copyright 2007,2008  Segher Boessenkool  <segher@kernel.crashing.org>
   2 // Licensed under the terms of the GNU GPL, version 2
   3 // http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
   4
   5 #include <stdio.h>
   6
   7 #include "tools.h"
   8
   9 static u8 buf[0x4000];
  10
  11 static void slot_checksum(u8 *x)
  12 {
  13         u32 i;
  14         u32 sum, nsum;
  15
  16         sum = 0;
  17         for (i = 0; i < 0x0a8c; i++)
  18                 sum += x[i];
  19         nsum = -(sum + 0x0a8c);
  20
  21         wbe32(x + 0x0a8c, sum);
  22         wbe32(x + 0x0a90, nsum);
  23 }
  24
  25 static void save_checksum(u8 *x)
  26 {
  27         u32 i;
  28         u16 sum, nsum;
  29
  30         slot_checksum(x + 8);
  31         slot_checksum(x + 8 + 0x0a94);
  32         slot_checksum(x + 8 + 2*0x0a94);
  33
  34         sum = 0;
  35         for (i = 0; i < 0x0ffe; i++)
  36                 sum += be16(x + 2*i);
  37         nsum = -(sum + 0x0ffe);
  38
  39         wbe16(x + 0x1ffc, sum);
  40         wbe16(x + 0x1ffe, nsum);
  41 }
  42
  43 int main(int argc, char **argv)
  44 {
  45         FILE *fp;
  46
  47         if (argc != 2) {
  48                 fprintf(stderr, "Usage: %s <zeldaTp.dat>\n", argv[0]);
  49                 return 1;
  50         }
  51
  52         fp = fopen(argv[1], "rb+");
  53         if (!fp)
  54                 fatal("open %s", argv[1]);
  55         if (fread(buf, 0x4000, 1, fp) != 1)
  56                 fatal("read %s", argv[1]);
  57
  58         save_checksum(buf);
  59         save_checksum(buf + 0x2000);
  60
  61         if (fseek(fp, 0, SEEK_SET))
  62                 fatal("seek");
  63         if (fwrite(buf, 0x4000, 1, fp) != 1)
  64                 fatal("write %s", argv[1]);
  65         fclose(fp);
  66
  67         return 0;
  68 }