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Emulation & ROM Hacking

Hex Editing Questions - Page 1

Hex Editing Questions

Posted by: J92R
Date: 2019-03-24 10:04:02
So, since I am limited to being on mobile, I just want a general idea of what the highest level of hacking can be done using just a hex editor.

Like, are there specific hex triggers or number/letter sets to look for that outline various aspects of these games, such as specific sections that outline just the Pokedex, or Trainer Pokemon, etc?

Just kind of curious what I can do to contribute to the hacking community with the limited resources I have. I mean, I already can contribute GBC music just fine, but I want to be able to add more, such as knowing how to hardcore nuzlocke into these games or enforcing specific moves to be used or making the games play themselves or something.

Like I get it, ASM is clearly the way to go and by far beyond superior to hex hacking, but I do feel that there has to be some use for deeper hex editing.

Re: Hex Editing Questions

Posted by: Parzival
Date: 2019-03-24 12:09:07
If you don't know anything about code flow, GBz80 opcodes, code start addresses or little-endian CPUs, not really. To edit code, you'd have to at least know the GBz80's opcodes and where whatever code you wish to alter STARTS, to avoid multi-byte opcode desync.

without a debugger it's nigh impossible to do more than edit data.

Re: Hex Editing Questions

Posted by: Sherkel
Date: 2019-03-25 23:00:02
I did all of what existed of Cyan (no, not that other very fleshed-out fangame that came later and actually got finished, but the REAL Cyan) without the slightest hint of what a debugger was. Custom moves, the script as seen there, other stuff I don't remember…aside from the sprites, I just had a hex editor and a lot of stuff open at once.

I'm not sure I'd advise developing the patience to do that on mobile, though. Maybe look to other goals for the time being?

Re: Hex Editing Questions

Posted by: ISSOtm
Date: 2019-03-26 06:52:55
My opinion on dev on mobile in general, no matter the dev: "forget it".

A hex editor can get you more or less far, if you have a ROM map (the .sym from pret's disasms would be a great help) but without editing the disassemblies, you'll only get so far.
Much more so if you're only editing data, not code.

Re: Hex Editing Questions

Posted by: Sherkel
Date: 2019-03-28 04:33:57
Man, things have sure changed…when did the disassembly reach the stage where editing it and rebuilding became the best way to hack?

Re: Hex Editing Questions

Posted by: Halfshadow
Date: 2019-03-28 05:24:50
Trough a hex editor + GBasmEditor and the PokéCrystal repository I made G/S/C 2.0.

But just in binary mode, without use the assembler, 'cause couldn't work with Silver and really with Gold (the disassembly isn't complete yet) and especially with italian roms, I made the hack also for international roms to release it to a larger audience, but I made it especially for me, and I'm italian. Was impossible with the pokécrystal disassembly create the 3 roms I wished when I was a kid without create fake Gold and Silver over PokéCrystal and without re-translate all. And to be honest, I released Crystal together with the other 5 roms, but I re-made it in only 3 days before the release, copying all the work from italia Crystal with the hex editor.

For me was very helpful.

The disassembly can make more easy add routines without be worried about free space (simply move the next bytes after your added) but have other issues, for me Cygwin worked very bad, crashed for graphic files broken (but just downloaded from the repository and untouched) and then, when fixed, compiled however bad roms. And I should had to translate them. No thanks. :P

I preferred repoint some routines to free space to add the safari battle type in all 6 the roms. :P

Re: Hex Editing Questions

Posted by: Raven Freak
Date: 2019-03-28 18:48:18
I've hacked games using hex editors, but honestly when there's better tools out there it's best to use them and in this case the disassembly is miles easier to use. I'm sure you could find a gbz80 to hex guide, and there are tools that directly edit roms but they're all made for computers. My suggestion is, if you want to hack you'll need a computer. You could possibly find a cheap chromebook, and that would do the trick. Just something good enough to emulate the GB, and you'd be set.