Hacking How to change basic settings from song to song

[biolizardshadow]

I am looking to learn a little bit about arm assembly and GBA games that use the MP2K sound engine. I am mainly wanting to learn how to change sound engine settings when a new song is loaded. I already have a grasp on how to change sound engine settings in general. I apparently need to know a little bit about assembly hacking or something (at least that's what ipatix told me) and so I have come here to try and figure out what I need to do to make this happen.

I am wanting to change the number of direct sound channels that are available from one song to the next. This is to maximize performance of the game I am hacking so I don't have to worry about slow down when there is a lot going on. I could just limit the number of playable direct sounds for the entire game; however, I would like to limit this to just each song so I can cut back on direct sound channels that I am not using for each song instead of having one overarching sound limiter.

Any help would with this endevour be appreciated!

 

[FAST6191]

Nice intro to GBA ARM assembly
http://www.coranac.com/tonc/text/asm.htm

Covers tracing in GBA hacking,
https://www.romhacking.net/documents/361/ (emulator it goes with http://web.archive.org/web/20130215155212/http://labmaster.bios.net.nz/vba-sdl-h/ granted most will point you at no$gba or even something like https://wrongbaud.github.io/posts/ghidra-debugger/)
The settings will likely fiddle with the audio aspects of the GBA so you would likely be altering these, either at instruction level or if it grabs settings from the ROM (like it might for speed, volume...) then you will know exactly where and how it decodes them (assembly is good stuff).

gbatek http://problemkaputt.de/gbatek.htm#armcpureference obviously has everything in detail about what goes, not sure what is gentler other than that TONC link above. You could find https://web.archive.org/web/2011090...om/products/processors/classic/arm7/index.php do something for you.

I have a few worked examples in my hacking docs but they are more for the cheat side of things. https://gbatemp.net/threads/gbatemp-rom-hacking-documentation-project-new-2016-edition-out.73394/ never the less.

https://www.cs.rit.edu/~tjh8300/CowBite/CowBiteSpec.htm for the sake of my usual link list. Don't think the quirky arm everything you never wanted to know link is worth it here, http://www.heyrick.co.uk/assembler/ will be linked because why not. For the sake of future forum searchers then for GBA audio http://belogic.com/gba/ is probably where most end up.