Etrian Odyssey 3 Drowned City: Making cheat codes, questions on RAM + share what's done so far

Discussion in 'NDS - ROM Hacking and Translations' started by demonata, Nov 15, 2015.

  1. demonata

    demonata Member

    Sep 26, 2010
    Hong Kong
    Just noticed that no$gba debugger is free already, so I picked it up and try to do something I wanted to.
    There are quite a few codes for the JP version that changes game mechanics instead of in-game values,
    and making the US version is my target.

    So far my first US code is working great:
    1st skill of a class is not restricted to main class anymore (can be selected in subclass skill list)
    020A6C84 E1A00000

    Now I'm working on my 2nd one, and needs some advice:
    I want to create a code in US version like this one,
    (JP version) item sell price multiplier (XX=03 will become 3 times)
    020001E0 E3A040XX
    020001E4 E0000490
    020001E8 E8BD8010
    020B5BE4 EAFD297D

    I looked into the JP-ver. memory to see what these addresses are...
    For the first 3 lines (also showing 1 line above/below here),
    I have no idea what these are, and so far I cannot trigger break point on them, or find similar pattern in US version.
    020001DC 64234507 strvst r4,[r3],-507h
    020001E0 DE42641A movle p4,2,c2,c10,0,r6
    020001E4 3A7A759F bcc 3E9D868h
    020001E8 8ABAFD00 bhi 0EBF5F0h
    020001EC BA392F23 blt 2E4BE80h

    For the last address 020B5BE4, I found that it's part of the logic that runs when I 1st enter sell items menu
    020B5BCC E5900008 ldr r0,[r0,8h]
    020B5BD0 EBFD8A25 bl 201846Ch
    020B5BD4 E1A01000 mov r1, r0
    020B5BD8 E59F0014 ldr r0,=3ECCCCCDh
    020B5BDC EBFD8A34 bl 20184B4h
    020B5BE0 EBFD89F2 bl 20183B0h
    020B5BE4 E8BD8010 pop r4,r15

    After applying the JP code to JP-ver. of game, basically 020B5BE4 routes to the above 3,
    which do the inflation math and the original pop instruction.
    020001E0 E3A04003 mov r4,3h<=multiply by 3 as example
    020001E4 E0000490 mul r0,r0,r4
    020001E8 E8BD8010 pop r4,r15
    020B5BE4 EAFD297D b 20001E0h

    For US version, I'm able to locate the same set of logic running when I enter sell menu, location:
    020B0458 E8BD8010 pop r4,r15

    But for the first 3 lines, I really don't know what to do with them....
    Are these address safe to be overwritten by this code (i.e. useless address???)

    FYI I have zero knowledge about assembly level programming :)
    ++If there is a better place to ask about these, please let me know what forum it is, thx
    Last edited by demonata, Nov 15, 2015
  2. AsPika2219

    AsPika2219 Pikachu going beach!

    Jun 17, 2010
    Cats City
    Nice codes! :lol: Plus, post your working codes at Game Hacking website here! Register first and enjoy your codes! :) :yaynds:
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