Homebrew Reverse engineering Golden Sun DS cheat code questions

[Wym92]

Please help me and explain how the cheat code below works, thank you!


521217CC D8BD87F0
02121838 E3500000
021217CC E1A00000
D0000000 00000000


If you need a "why", the reason is next: As we all know (maybe), there exists an RN method to get weapons and items from enemies in the Golden Sun 1 and TLA, this made the gaming easy and interesting. However, the DS version doesn't have that anymore. Now, I know one cheat code can make that happen, but I can't understand how it works, obviously it's not simply lock three numbers to three locations. Please help me with it, thanks!

 

[FAST6191]

What region is this for by the way?
I do not have any of them in front of me but looking at http://gbatemp.net/threads/reverse-engineering-golden-sun-dark-dawn-exp-multiplyer-code.272880/ you might well be in the binary for this. However it is quite late in the memory ( http://nocash.emubase.de/gbatek.htm#dsmemorymaps ) and with the code being what it is (a check and then run) it may instead be an overlay. If you are not familiar with the idea of overlays they are small snippets of code that the DS can put in memory to expand what it can do, most games use them for extra code but some use them for all sorts of things and some even use them for everything.

ANyway
521217CC D8BD87F0
5XXXXXXX YYYYYYYY is an equal to type cheat.

It checks if 021217CC in memory is equal to D8BD87F0

0 codes are 32 bit writes, however in this case they will be held back by the 5 code above if it is not equal. One overwrites the location of the check where another overwrites a location not long after it.

D0 codes terminate the equal to condition check. I am not sure if it is strictly necessary here (technically the equal check should have ended with the codes) but it is good form to do so (lesser cheat engines might ignore it).

I will need to know/figure out the ROM region before I start disassembling the stuff above. I could disassemble the code payloads there but it is frequently the stuff around it that helps out.

 

[Wym92]

What region is this for by the way?
I do not have any of them in front of me but looking at http://gbatemp.net/threads/reverse-engineering-golden-sun-dark-dawn-exp-multiplyer-code.272880/ you might well be in the binary for this. However it is quite late in the memory ( http://nocash.emubase.de/gbatek.htm#dsmemorymaps ) and with the code being what it is (a check and then run) it may instead be an overlay. If you are not familiar with the idea of overlays they are small snippets of code that the DS can put in memory to expand what it can do, most games use them for extra code but some use them for all sorts of things and some even use them for everything.

ANyway
521217CC D8BD87F0
5XXXXXXX YYYYYYYY is an equal to type cheat.

It checks if 021217CC in memory is equal to D8BD87F0

0 codes are 32 bit writes, however in this case they will be held back by the 5 code above if it is not equal. One overwrites the location of the check where anotheroverwrites a location not long after it.

D0 codes terminate the equal to condition check. I am not sure if it is strictly necessary here (technically the equal check should have ended with the codes) but it is good form to do so (lesser cheat engines might ignore it).

I will need to know/figure out the ROM region before I start disassembling the stuff above. I could disassemble the code payloads there but it is frequently the stuff around it that helps out.

WOW that's a lot for me to understand, I don't have any experience or knowledge on this.
The code is for the japan version of Golden Sun DS.

 

[Langin]

You should remove the romlink. It's against the boardrules. Is Golden sun too hard? o_o

 

[Wym92]

You should remove the romlink. It's against the boardrules. Is Golden sun too hard? o_o

Oh I didn't know that, sorry~