At 03.07.2002, 23:11, Paul Slocum wrote:
> I tried the idea of interleaving the color data, but I ran into a
> problem: to make it work right I have to AND out the zero bit on the X
> register, which best I can tell, takes as many cycles as doing an ASL on
> the X like I was doing. I couldn't figure out a way to solve this.
I see. Coding the loop twice would help, but that is not what we are
looking for. Must think about a better solution.
> I just accepted that as a fact of life early on. :o( But if other games
> can get away with an HMOVE comb, I figure I can get away with
> that. !o) It doesn't look quite as bad on a real Atari. I might try to
> clean up the timing a bit when the game is done and I know the kernal won't
> change any more.
Agreed, it's a good idea to do this at the very end.
> I just don't think there's any hope of finding 4 bytes. Notice I'm using
> everything from $80 to $FF during the kernal. I cringe to think about
> trying to find even 2 bytes.
Hm, I don't see the routine for drawing the score, but you might be able
to reuse the pointers used there. Are you reusing registers at
all (except for title screen)?
> I think I'm just going to hope to squeeze out enough cycles to do your
> original trick. It looks like it would take 20 cycles to do both
> marbles. Maybe I could even find a way to alternate doing this check on
> player 1 and 2 with each loop cycle.
Do I understand you right? You want to check once per loop if you have
to draw a marble in one of the following 13 lines. If yes, the pointer
should point to valid data and if not, it points to zero bytes. Right?
Sounds like a good idea.
> And I would change it to this at a max cost of 10 cycles, I think:
> tya ;2
> adc #13 ;2
> adc pMarble ;3
> bcc noMarbleReset ;2/3
> sta pMarble ;3
> jmp marbleReset ;3
> noMarbleReset
> lda (pMarble),y ;4*
> sta GRP0 ;3
> marbleReset
Hm, I do not understand how this should work. How do you initialize
pMarble?
Have fun!
Thomas
_______________________________________________________
Thomas Jentzsch | *** Every bit is sacred ! ***
tjentzsch at web dot de |
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