Hi there!
> ^ How can this always produce the same amount of cycles?
> ^ Why arent all the instruction cycles counted in comments?
> ^ This code is obviously not needed for me, however I'm not sure how
> ^many other cycles exactly I have to replace it with.
These cycles don't matter. They're not the same amount either.
> sta COLUP0 ; 3
> sta COLUP1 ; 3 = 10 <-- When I count, I get much more
> than 10?
>
> ldy MsgTab,x ; 4
> ^??????? Totally lost here |Load height of graphic?
I'd assume it displays different messages, so depending on the message he has to display different letters. X is the message ID and the table contains the letters.
> lda LetterPtrTab,y ; 4
> sta digitPtr ; 3
> ^LetterPtrTab,Y = Address of first 8x8 Graphic?
I'd think so.
> lda LetterPtrTab+1,y ; 4
> ^Here is where I get lost? I don't understand how this gets compiled
> ^If LetterPtrTab = $1200 and Y is $05, then this returns $1200 + 1 + 5?
> ($1206)???
It returns the content at the address $1206.
> ^Shouldn't this get the last byte of the second graphic? I'm confused how it
> does this?
the 6 digitPtr are loaded with the adresses of the chars to display.
> sta digitPtr+2 ; 3
> ^digitPtr is in Zero Page... So the graphic data is loaded into RAM...
No, just the pointer is set.
> lda LetterPtrTab+2,y ; 4
> sta digitPtr+4 ; 3
> lda LetterPtrTab+3,y ; 4
> sta digitPtr+6 ; 3
> lda LetterPtrTab+4,y ; 4
> sta digitPtr+8 ; 3
> lda LetterPtrTab+5,y ; 4
> sta digitPtr+10 ; 3 = 46
>
>
>
> ldy #5 ; 2
> ; ldy MsgHeightTab-1,x
> txa ; 2 don't change C!
> eor #MSG_C_2000 ; 2
> bne .msgLoop ; 2³
> ldy #7 ; 2 = 7/8
> .msgLoop:
>
> ^ All graphics are 5 height, except Copyright which is 7...
> ^ These are all wasted cycles for me... in order for this to work for me
> however,
> ^ I have to get this exact cycle count?
Again, no, since the code below kicks in with a WSYNC. Just load Y with your height.
> dey ; 2 61
> sty tmpVar ; 3 64
> lda (digitPtr+$8),y ; 5 69
> tax ; 2 71
> sta WSYNC ; 3 --- 76 ---
> lda (digitPtr),y ; 5 5
> sta GRP0 ; 3 8
> lda (digitPtr+$2),y ; 5 13
> sta GRP1 ; 3 16
> lda (digitPtr+$4),y ; 5 21
> sta GRP0 ; 3 24
> lda (digitPtr+$6),y ; 5 29
> sta tmpVar2 ; 3 32
> lda (digitPtr+$a),y ; 5 37
> ldy.w tmpVar2 ; 4 41
> sty GRP1 ; 3 44
> stx GRP0 ; 3 47
> sta GRP1 ; 3 50
> sta GRP0 ; 3 53
> ldy tmpVar ; 3 56
> bne .msgLoop ; 2³ 59
>
> ^This all makes sense
Sure? :-)
> sty GRP0
> sty GRP1
> sty GRP0
> ^Why is GRP0 cleared twice?
> rts
Both sprites are VDEL'd, so one write is only *preloaded* until triggered by the next.
> So assuming my graphics data is as follows, How do I get this subroutine to
> draw it correctly?
> ORG $1200
> Graphic0 .byte $00,$00,$00,$00,$00,$00,$00,$00
> Graphic1 .byte $00,$00,$00,$00,$00,$00,$00,$00
> Graphic2 .byte $00,$00,$00,$00,$00,$00,$00,$00
> Graphic3 .byte $00,$00,$00,$00,$00,$00,$00,$00
> Graphic4 .byte $00,$00,$00,$00,$00,$00,$00,$00
> Graphic5 .byte $00,$00,$00,$00,$00,$00,$00,$00
Set up LetterPtrTab like this:
LetterPtrTab .word Graphic0, Graphic1, Graphic2, Graphic3, Graphic4, Graphic5
Greetings,
Manuel
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