I'm thinking about writing (or at least trying to write) an editor, and I first want to poke around the ROM to see if I understand the format. The problem is that I can't follow the website. I tried following this formula to convert the offset to an address, but I'm not getting any useful results, e.g. the location that's supposed to be "empty and filled with $FF" has no $FF anywhere near it.
Am I missing something? Am I doing it completely wrong?
Okay, so somehow I determined that, in SNEStoPC(), header is -0x200. I'm not sure if my ROM is weird or it's actually supposed to be like that, but the values match up with the ROM map.
The one on the romhack.wikia uses a boolean to tell if it has a header or not, the one I posted requires header to be 0 if there is no header and 0x200 if there is.
Okay, now I'm confused again. For example, I can find the empty text at $11:98BF if I were to set the header to -512 (yes, negative), but the empty text at $03:EBD9 if the header is set to 0.
I am using the .sfc file that was mentioned in the sticky, and I'm assuming that it's a headerless file, yet the values for the header are inconsistent for some reason.
Guess and check, basically. If the data matches up with the description in the ROM map, I adjust the header accordingly.
Over all, the header value is not too important to me. All I'm trying to do is determine the PC address from the offset, which I will use to write my program. I guess, for now, I'll just keep guessing and checking because it works. Sorta.
Thats not really the best way to do it, I would suggest at least checking if it has a .sfc (non headered ROM) or .smc (headered ROM) extension. Or you can divide the ROM size by 0x8000 and keep the remainder:
Code
int header = romsize%0x8000;
if (header != 0x200) {
printf("ROM is un-headered.\n");
} else {
// header will be 0 here
printf("ROM is headered.");
}
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