[stella] kernal klunk

Subject: [stella] kernal klunk
From: KirkIsrael@xxxxxxxxxxxxx
Date: 6 Feb 2004 01:22:47 -0000
So I'm having trouble with my kernal...but I can't understand
why I'm seeing it *now*, everything I've been changing is in 
VBLANK (the fractional positioning, and I just added in a routine
to rebound off the floor at 1/2 the descending speed) and the
Kernal, which seemed pretty solid before, should be unaffected.

The Kernal is a bit messy though, skipdraw techniques with code 
to decode and set the warlords-like walls behind interspersed

And my attempts at debugging were for not...I thought I was possibly
running out of TIME in the VBLANK (though I thought that seemed 
relatively unlikely) so I added in a bunch of NOPs...*way* too many
NOPs caused obvious problems to occur (screen starts getting drawn 
late) but just a certain numer of SLEEP cycles seemed to make the 
issue go away.

The bin is at 
and the source is at

You can most easily reproduce the issue by putting it on 2 players,
letting both players drop, and seeing what happens to the screen
when the 2 players and the ball are on the same part of the screen.
This effect doesn't seem to happen in the eariler bins at 
http://alienbill.com/joustpong/ though the Oct 13 bin still had a 
bug where I wasn't clearing out GRP0/1, so they stretched a bit.

Any ideas? I think the version posted has been copying the high byte
of the player position into a seperate memory location

	LDA slowP0YCoordFromBottom+1
	STA copyIntegerCoordP0

	LDA slowP1YCoordFromBottom+1
	STA copyIntegerCoordP1

 just on the wacky chance that 
        SBC copyIntegerCoordP0
was faster than 
        SBC slowP1YCoordFromBottom+1
--though I assume the two previous statements assemble into 
equivalent code?

Thanks for any debugging help!

KirkIsrael@xxxxxxxxxxxxx    http://kisrael.com
"As they say in my country, the only thing that separates us from the animals 
  are mindless superstition and pointless ritual."--Latka Gravas,"Taxi"   

Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/

Current Thread