[stella] Indirect Why?

["Ruffin Bailey" <rufbo@xxxxxxxxxxxxx>]

Ok, I've been pouring over my code a bit _too_ long I suppose.  I just can't
get indirect y to work the way I'd like.

I've got some bytes at the end of my demo that I'd like to use as the player
graphic.  I'm setting those up like this:

 ORG $FF01

  .byte %10101010, %01010101,%10101010, %01010101

Then in earlier in my demo, I'm assigning this position to two bytes in RAM
like so:

       LDA    #$00
       STA    CTRLPF

;=================================================
; setting up where the player graphics are located
;=================================================

       STA    $90 ; zero
       LDA    #$FF
       STA    $91 ; FF + 00 = FF00 (used with an indirect Y below)

Now 90 should be the LSB and == #$00 and 91 should be the MSB and == #$FF,
correct?  Just one byte away from where I want to grab my graphic info.

So during the screendraw, I've got this code to do just that:

       LDY    #$01
       STA    WSYNC

LF0AD:
       INX
       CPX    #$60
       BEQ    DrawThePF

      LDA $90,Y       ; "FF" + "00" = FF00; FF00 + Y = FF00 + 1 = FF01
       STA GRP0
       INY

       STA    WSYNC
       CPY    #$10
       BNE    LF0AD

Did I screw up somewhere?  Let me just say it's not working... I get one
scan line worth of player, and that's it.

Thanks for the help, and sorry if this is such a simple matter it's
embarassing.  I'll slap the full code up at:

http://members.aol.com/mactari/why.asm

Thanks again,

Ruffin Bailey


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