Re: [stella] debuggers

Subject: Re: [stella] debuggers
From: Bad Panda Bear <badpandabear@xxxxxxxxxx>
Date: Tue, 03 Feb 2004 21:07:23 -0800
Glenn Saunders wrote:

For the record, is there an easily identified part of the current Stella codebase on Sourceforge to wedge in a debugger? The entire 6502 system is completely simulated as objects and in theory it should be able to "monitor" the machine through an external module, right? I'm not volunteering as I don't know C++, but I'd like to know from someone who DOES if they've been able to at least conceptualize which section of the code would need to be altered to make this happen.

There are probably people on this list that know more about the stella source code than I do, but I briefly looked through the stella code and it looks like the whole src/emucore section of code could be used as the foundation of an interactive debugger. Specifically the M6502, D6502 and System classes have the ability to inspect/modify CPU state, inspect memory, disassemble code, etc. The only thing I couldn't find is a way to set breakpoints. But I may not have looked hard enough.

I can think of so many important things a 2600-specific debugger could do.

For instance, you could flag start and stop points for measuring how many cycles a section of code takes to execute. (Think Overscan/VBlank). That way you'll know very easily how many cycles you have to spare (if any) you have.

I was thinking it would be cool to be able to step forward/backwards a scanline at a time, or one frame at a time, in addition to normal instruction/cycle stepping.

It would also be cool to be able to specify script files for controller input, so one could make automated regression tests for their games.

Dusty Reichwein

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