PyBoy•6mo ago

Extracting score from memory

Hi, I'm trying to make an RL agent for gameboy tennis. I need a way to get the score after each point. One method is by processing the pixel data but I thought it would be more efficient/reliable to read it directly from memory. I'm not really sure where to start. I've installed visualboyadvance-m which has a memory viewer but a lot of values change so no idea how to narrow it down. Any help would be appreciated.

17 Replies

capnspacehook•6mo ago

This website has a lot of good info https://datacrystal.tcrf.net/wiki/Tetris_(Game_Boy)/RAM_map

RAM map

capnspacehook•6mo ago

Pyboy has a tetris game wrapper that may do this already as well

BET Adsorption•6mo ago

Finding a disassembly of the ROM would be likely helpful as well. Pokemon Red has really-well-documented disassemblies, which proved vital for success.

pkr895OP•6mo ago

unfortunately tennis doesn't seem to be popular enough for someone to have posted a RAM map or made a wrapper

capnspacehook•6mo ago

Oh my bad misread that as tetris

pkr895OP•6mo ago

is this a lot of effort? I've been screen recording the memory as I play and I've identified some values that correlate with movement/winning games obv that's prone to errors but this project is about RL algorithms so i'd rather not waste time on this stuff

BET Adsorption•6mo ago

finding the disassembly is minimal effort. disassembling yourself? that's maximal effort i'm porting the atari 2600 game enduro to c. i found one disassembly, but it's only just the assembly itself. and it has been minimally edited. needless to say, 3000 lines of

    lda     timeCycle               ;
    and     #$3f                    ;
    cmp     #$08                    ;
    bcs     Lf419                   ;
    lda     carsRemainingLo         ;
    ora     carsRemainingHi         ; cars remaining?
    beq     Lf419                   ;  no, skip

    lda     timeCycle               ;
    and     #$3f                    ;
    cmp     #$08                    ;
    bcs     Lf419                   ;
    lda     carsRemainingLo         ;
    ora     carsRemainingHi         ; cars remaining?
    beq     Lf419                   ;  no, skip

is difficult at best to utilize amazing what fits into 3kb tho

pkr895OP•6mo ago

Can you give me a brief overview of the steps needed https://github.com/mattcurrie/mgbdis?origin=serp_auto Disassemble with something like this Then look through the assembly for variables related to score?

GitHub

GitHub - mattcurrie/mgbdis: Game Boy ROM disassembler with RGBDS co...

Game Boy ROM disassembler with RGBDS compatible output - mattcurrie/mgbdis

BET Adsorption•6mo ago

no clue. 😭 maybe someone else here has better knowledge @Sky

Bækalfen•6mo ago

It's a good start if you've already identified some memory areas. That's not the same as an actual disassembly.

Bækalfen•6mo ago

Did you check out the memory scanner in the docs? https://docs.pyboy.dk/api/memory_scanner.html

pyboy.api.memory_scanner API documentation

Bækalfen•6mo ago

If there's always something on the screen that tells you the score, you can also go that way

pkr895OP•6mo ago

Not yet but looks helpful The score appears and disappears after each point And I doubt the scores are stored as 15/30/40 in memory

Bækalfen•6mo ago

You can see this as an example https://github.com/Baekalfen/PyBoy/blob/8cf3f1f11dd34e6838174ac3680553bf962e4171/pyboy/plugins/game_wrapper_tetris.py#L94 You can copy the function from here https://github.com/Baekalfen/PyBoy/blob/8cf3f1f11dd34e6838174ac3680553bf962e4171/pyboy/plugins/base_plugin.py#L278

Sky•6mo ago

Unfortunately I never digged into using disassembling tools on gb, at most I relied on good old memory scanning. My x86 asm reversing period on games, ended like 13 years ago 😅

pkr895OP•6mo ago

Forgot to say but I managed to find the memory address manually after not too long. It's 0xC0DD for player score and 0xC0DE for cpu. Also found out you can pause the game at any time to check score so I could have read it like in the Tetris example. Thanks all of you for your help.

BET Adsorption•6mo ago

you could say you found the C0DE wonder if that was on purpose??

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Extracting score from memory

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