Hi,
I'm still learning Indirect Y addressing (and writing a "how to" as I go along in case I forget later) but I think you may need to initialize both the hi and lo byte of the address (since Indirect Y expects a 16-bit address).
For example, you're stuffing the value #$B0 (least significant byte of the address) in tmpVar3 but when you go to dereference it later (with "lda (tmpVar3),y"), it's reading the address as "$xxB0" where "$xx" is garbage.
Try this...
lda #PlayerHand
sta tmpVar3
lda #0
sta tmpVar3+1
lda #Player3
sta tmpVar4
lda #0
sta tmpVar4+1
We're simply putting "$00" as the most significant byte of the address so the tmpVar3 pointer will look like "$00B0" and the tmpVar4 pointer will hold "$00A0". Oh, and be sure both tmpVars are 2 bytes in size!
I hope that helps. If not, we'll both learn something! :)
Jason
On Tuesday, October 7, 2003, at 07:33 PM, Chris Larkin wrote:
It could just be that I still don't fully understand indirect addressing... But this should work?
?
I know this loop does not replace the first byte in either location, but it should "swap" the others... However
my results are not very good :-)?What am I doing wrong?
?
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PlayerHand = $B0 ; -> $B6
Player3 = $A0 ; -> $A6
?
TradeHands
??? ?LDY #7
??? ?LDA #PlayerHand
??? ?STA tmpVar3
??? ?LDA #Player3
??? ?STA tmpVar4
TradeLoop
??? ?LDA (tmpVar3),y
??? ?STA tmpVar2
??? ?LDA (tmpVar4),y
?????STA (tmpVar3),y
?????LDA tmpVar2
??? ?STA (tmpVar4),y
??? ?DEY
??? ?BNE TradeLoop
??? ?RTS
?
