Eador Genesis GNU/Linux port

$ ./eador-conv -h
Usage : ./eador-conv [option]... original_save converted_save
Converts Eador : Genesis savegames between 32-bit and 64-bit formats

  -h, --help  this help message
  --64        convert from 32-bit to 64-bit (default)
  --32        convert from 64-bit to 32-bit

#include <allegro>

#define CMP_PFX_32 12628
#define CMP_PFX_64 12632
#define PLAYER_32 4148
#define PLAYER_64 4160
#define SHARD_32 212
#define SHARD_64 224
#define MASK_32 28
#define MASK_64 40
#define TUTORIAL 288

int main(int argc, char **argv)
{
   char buf[12800];

   if (argc != 3)
      return 1;

   PACKFILE *in  = pack_fopen(argv[1], F_READ_PACKED);
   PACKFILE *out = pack_fopen(argv[2], F_WRITE_PACKED);

   if (!in || !out)
      return 2;

   if (pack_getc(in) != 'o' || pack_getc(in) != 'k' || pack_getc(in) != 2)
      return 3;

   pack_fwrite("ok\002", 3, out);

   pack_fread (buf, CMP_PFX_32, in);
   memset(buf + CMP_PFX_32, 0, CMP_PFX_64 - CMP_PFX_32);
   pack_fwrite(buf, CMP_PFX_64, out);

   int shard_count = ((int *)buf)[3];

   for (int i = 0; i < 33; ++i)
   {
      pack_fread (buf, PLAYER_32, in);
      memset(buf + PLAYER_32 - 8, 0, PLAYER_64 - PLAYER_32 + 8);
      pack_fwrite(buf, PLAYER_64, out);
   }

   for (int i = 0; i < shard_count; ++i)
   {
      pack_fread (buf, SHARD_32, in);
      memset(buf + SHARD_32 - 12, 0, SHARD_64 - SHARD_32 + 12);
      pack_fwrite(buf, SHARD_64, out);

      pack_fread (buf, MASK_32, in);
      memset(buf + MASK_32 - 12, 0, MASK_64 - MASK_32 + 12);
      pack_fwrite(buf, MASK_64, out);
   }

   pack_fread (buf, TUTORIAL, in);
   pack_fwrite(buf, TUTORIAL, out);

   pack_fclose(in);
   pack_fclose(out);

   return 0;
}