Just slowly plugging along. I’ve been alternating between trying to understand snippets of code in Ghidra, looking at memory changes at runtime in Mesen, changing them to see what they do, and tracing execution paths in the debugger.
That’s probably the cycle I’ll be doing all the way through.
I can’t debug through Ghidra but it’s got extensive commenting/renaming features. Mesen’s debugger has a few label creation/renaming features but it’s a more limited. I don’t seem to be able to add comments, which would’ve been nice. The debugging features are pretty great, though.
One thing I haven’t seen in Mesen is a feature to track whether certain values went up or down between breaks. It only marks values that have been written to. It would help pinpoint memory values that go down, like health bars or time counters.
So far in memory I’ve identified some various timers, the random number generator, player lives and progression, joystick/oam/ppu register copies. I’ve also found update functions for what I guess are the different “modes”, like the title screen and game play, with each mode having multiple functions, which are maybe sub-modes. Haven’t gone too deeply into it yet. Identified a few simple utility get/set/clear functions for memory and PPU.
I realized I could look at Game Genie codes to help figure out certain values. There aren’t that many codes out there but it did identify a few things.
Moved the project file to the cloud to at least have some semblance of backup and version control. I’ll have to figure out how I want to store this in GitHub or something.
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