[atari7800] Re: Question about character data

  • From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
  • To: <atari7800@xxxxxxxxxxxxx>
  • Date: Wed, 11 Aug 2004 22:45:32 +0200

>>
I'm looking at Eckhard's backdoor.das file and I see his fonts are upside
down. Is this the way MARIA reads the data? I can't seem to find anywhere in
his source where he tells MARIA the data is stored upside down or a
decrement loop to load the data.
<<

Have another look at the paragraphs about the Display List List.
The OFFSET value that you specify in a DLL entry is decremented
after each scanline untill it goes negative. It also gets added
to the high address byte for the graphics data. Therefore you
need to store your graphics data upside down with the data for
each scanline being put 256 bytes before the data for the previous
scanline.


Ciao, Eckhard Stolberg


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