Manuel Polik wrote:
> AND #$0F ; Manuels "forget about EOR/ASL
> TAY ; nonsense" magic :-)
> LDA hmovetab,Y ;
> STA HMP1 ; Fine Position sprite 1
>hmovetab
> .byte $80,$70,$60,$50,$40,$30,$20,$10,$00
> .byte $F0,$E0,$D0,$C0,$B0,$A0,$90
Good work Manuel! Did you find this trick in other games too?
Sometimes it might be useful not to use the index registers
(X/Y). Then we'll need that "EOR/ASL nonsense" again. :-)
EOR #$0F
SBC #$06 ; -7 (carry is clear)
ASL
ASL
ASL
ASL
STA HMP1 ; Fine Position sprite 1
That costs 4 extra cycles, but keeps the Y-register (so you
might save the 6 cycles for storing/loading) and also saves 14
bytes of ROM.
The only problem with that code is, that the carry might be set
after the last ASL. So it will not work for Manuel, but might
be useful elsewhere.
Have fun!
Thomas
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