Re: [cc65] Hello, and a memory corruption (?) issue when optimizing

From: Maik Merten <maikmerten1googlemail.com>
Date: 2013-06-10 19:00:05
Am 09.06.2013 21:25, schrieb Ullrich von Bassewitz:
> It might be a problem caused by the source, not by the compiler. So yes, will
> have to give it a closer look.

Okay, now I dug a bit deeper. I'm still not quite fluent with C64 
development in general, so your advise on using Vice's monitor 
functionality for sure was a good one!

Things I tested:

  * I made sure that the bitmap data for the title screen is indeed 
included correctly in the optimized binary. I found the data to start at 
offset 0x165f.

  * Directly after loading the program with LOAD "*",8 (which should 
load the binary with an offset of $0801 into memory) I dumped the memory 
from 0x1e60 to 0x4571 into a file.

  * After starting the program (and displaying the corrupted image) I 
did another memory dump from 0x1e60 to 0x4571. Both dumps are identical, 
so I think I can rule out that the original bitmap data got messed up.


This is interesting to toy around with. From the looks of the 
corruption, I'd guess that either the video-RAM or color-RAM ends up 
with wrong values. I should dump those memory when displaying the 
corrupted image and compare.


Maik

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Received on Mon Jun 10 19:00:17 2013

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