[NDS] Execute an AR Code only once?

[Helder]

What's at the 3rd line's address? Seems like an odd address.

[rimsky82]

Agreed, without looking at the memory map... An emulator might allow a write to 0x2FFFFFF, but the DS hardware might not. I would run the game and look for some RAM that isn't used to store that value.

[Demonic722]

When in doubt, just write to 0x02000000 since it's usually unused/free. If you find another spot, make sure it's between 0x02000000 and 0x02400000.

[MichiS97]

When in doubt, just write to 0x02000000 since it's usually unused/free. If you find another spot, make sure it's between 0x02000000 and 0x02400000.

Oh so that's the memory range you can write to with AR Codes? I couldn't find that anywhere

[Pyriel]

http://problemkaputt.de/gbatek.htm#dsmemorymaps

That's the range of main memory anyway. It's theoretically possible that some other addresses could be writable with the right offset and codes, but it's generally best to stick with user memory ranges unless you know what you're doing.

Although, according to this, only 3 KB of the BIOS range is actually used, so if it's writable and initialized, the unused portions would make an ideal, fixed-location code cave. Assuming you can safely branch into code there without issuing syscalls or whatever the ARM/NDS equivalent is. I'm guessing that one or more difficulties make that impossible or infeasible, otherwise people more familiar with the NDS would probably have documented how to do it.

[MichiS97]

I really don't understand it, I'm using a new address now and it's the same problem: It works just fine on Desmume and not at all on the DS

221BA598 00000002
94000130 FCFE0000
A23F7750 00000001
DB000000 021BA605
D4000000 00000002
D8000000 021BA605
123F7750 00000001
D2000000 00000000