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2012-03-02 21:36

Kickback

Registered: Apr 2004
Posts: 97

Raster timng per line

I have been going over this idea in my head for sometime now, but wasn't sure if it was actually possible in a LOOP form.

I wanted to store color to $d020, 21, 22, and 23. I was working with some of my old code to achieve this but wasn't sure if this was possible in a loop form.

Sample:

ldx #$00
lda color,x
sta $d020
sta $d021
lda color2,x
sta $d022
lda color3,x
sta $d023
.
.
.
inx
cpx #$20
bne -

Something to that degree, ofcourse the timing routine isn't in that code, I am more wondering if its even possible to do or am I beating a dead horse.

I have seen this done before in a unrolled loop, which makes me believe it's not possible in a rolled loop?

Any help here mates!

2012-03-03 06:32

Marauder/GSS
Account closed

Registered: Jul 2006
Posts: 224

yes, should be possible in a loop... I did something like that in MRD's After Party Demo, see the RIFFS logo on top...

check the IRQ-routine at $10BF:

IRQ1     ...
         LDA #$43
         STA $D012
         LDA #<(IRQ2)
         STA $0314
         LDA #>(IRQ2)
         STA $0315
         JMP $FEBC

IRQ2     LDA #$10
         STA $D016
         BIT $FF
         BIT $FFFF
         BIT $FFFF
         BIT $FFFF
         BIT $FFFF
         LDX #$00
I201     LDY #$06
I200     LDA $1B00,X
         STA $D022
         LDA $17A0,X
         STA $D020
         STA $D021
         LDA $1A00,X
         STA $D023
         INX
         NOP
         NOP
         NOP
         NOP
         NOP
         NOP
         NOP
         NOP
         NOP
         NOP
         NOP
         BIT $EA
         BIT $EA
         DEY
         BNE I200
         LDA $1B00,X
         STA $D022
         LDA $17A0,X
         STA $D020
         STA $D021
         LDA $1A00,X
         STA $D023
         INX
         LDA $17A0,X
         STA $D021
         STA $D020
         LDA $1B00,X
         STA $D022
         LDA $1A00,X
         STA $D023
         INX
         BIT $EA
         NOP
         NOP
         NOP
         NOP
         NOP
         NOP
         NOP
         CPX #$40
         BNE I201
         ASL $D019
         ...

hope it helps...
-Jo

2012-03-04 07:40

Kickback

Registered: Apr 2004
Posts: 97

Thanks mate!!

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