Hacking Emulation ROM Hack GBA Emulator Translation inserting text without crashing

[q-tipper]

i want to add text without crashing, let me explain:
If, for example, I add a single letter to a text, adding 1 byte to the game, the game will no longer work, is there a way to avoid this?

 

[Maeson]

Of course the game will not longer work, by adding bytes of information you shift everything after those bytes, so when the code of the game looks for the exact part of a code or text, it is no longer there and reads the incorrect data.

If you want to change text, you have to either use the space already used by the text, or learn how the text routine work, locate free space on the rom and relocate the text there, changing the pointers that tell the game where it needs to look for each string of text.

 

[q-tipper]

is the "free space" empty or is it just a bunch of random chracters?

 

[Maeson]

It's often long strings of "00", sometimes "FF". "Random" characters are game code.


You can check romhacking.net for tutorials and newbie information on this stuff.

 

[q-tipper]

the weird thing is, the text doesnt look like it has pointers

 

[master801]

Fix the checksum otherwise the game won't boot. This is common for N64, NDS and other consoles.

https://www.romhacking.net/utilities/1343/

EDIT: Linked to a Game Boy tool. This is the Game Boy Advance tool: https://gbatemp.net/download/gbata-gba-tool-advance-0-7a.223/

 

[q-tipper]

im editing text in a gba game, not gameboy or gameboy color, i feel like i should've said that

 

[master801]

My bad, I linked the wrong tool.

https://gbatemp.net/download/gbata-gba-tool-advance-0-7a.223/

 

[FAST6191]

Hashes should not be a problem for the GBA.

As above you need to repoint. GBA pointers are typically within the ROM itself, which leads most to the shorthand of "pointers start with 08" as the GBA ROM is visible at 08000000 through 09FFFFFF (and a few other locations but I am going to be hard pressed to find an example of anything using those) and as most are 16 megs or less then only 08 gets touched. To that end most search for 08 and if you have a bunch of them with say 6 bytes between them (08??##%% where the blank is the location in the ROM, give or take some byte flipping, though 08 is a perfectly valid thing to find within the pointer itself so don't expect hard 6 byte gaps, and I have seen other things within pointer fields like formatting commands). Obviously everything uses pointers but text should be fairly obvious (if you know where the text is then the pointer will match, and most other things will be fairly fixed lengths where text might not be).

Most look for extra space at the end of the ROM (00 and FF being the usual filler, I have examples of games that use it as useful info but most of those come down to "skip 100 bytes and then start using that as blank space").
Bonus for the GBA is you can trivially expand a GBA ROM to 32 megabytes if you need to (literally just add space to the end of the ROM), though if you can keep it under 16 megs then that is considered good form for various flash cart users (very few will not be able to run the full 32 but it can be tedious vs 16).