[CSDb] - User Forums - Reverse debugging in emulator?

You are not logged in - nap

CSDb User Forums

Forums > C64 Coding > Reverse debugging in emulator?

2012-09-15 13:41

Paulko64

Registered: Jul 2010
Posts: 24

Reverse debugging in emulator?

Hi all,

I'm currently working on a game-project that has high irregular CPU load during each frame. I've coded everything in such a way that all this irregular code is ran during a mainloop and starting of the routines is regulated during raster-irqs (besides the multiplexor and music calls).

Now this all works perfectly except for once in a few minutes my game crashes (CPU-jam), because it apparently jumped to a strange adres (ZP in my case). I'm not sure what happened but maybe I didn't end the irqs well enough, or perhaps I used the same ZP-adres for indirect adressing in both main and irq-code, which then screws up code if an irq fires at exactly the right (wrong!) moment...

Anyhow, this proves to be very hard to troubleshoot. So I thought, isn't there an emulater that supports some kind of "reverse debugging"? I.e. when I get a CPU-jam can I trace back what instructions were used just before? Or maybe an emulator that supports writing all instructions executed to a textfile which I can then trace back? Although this last option will probably generate a HUGE trace-file.

Does anybody know how to accomplish something like this?

Thanks,

PaulKo64

... 20 posts hidden. Click here to view all posts....

2012-09-26 20:00

Paulko64

Registered: Jul 2010
Posts: 24

Yeah, finally solved the bug! I couldn't have done it without the "chis" command.

What happened was that due to a negative offset an unrelated routine corrupted the hi-byte in one of my jump-tables. Now minutes later when actually using this particular jump-adres I ended up in zero-page where after some random instructions it encounterd a BRK instruction and crashed soon thereafter!

So luckily I can now continue with the rest of the game.

Thanks all!

Previous - 1 | 2 | 3 - Next

Refresh

Subscribe to this thread: