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IamRob
PostPosted: Wed Sep 06, 2023 2:58 am 
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Joined: Sun Apr 26, 2020 3:08 am
Posts: 357
I guess the routine I posted fails in one respect. If the Accumulator is already at $FF, then gets incremented to $00, then the subtraction at the bottom of the routine will fail as the carry will be cleared in that case.
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BigEd
PostPosted: Wed Sep 06, 2023 7:11 am 
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Joined: Thu Dec 11, 2008 1:28 pm
Posts: 10800
Location: England
oh no!
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IamRob
PostPosted: Fri Dec 15, 2023 10:51 pm 
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Posts: 357
* I just had to revisit this thread as I couldn’t get this out of my head,

* This should be up there for one of the smallest/fastest
* The smallest

INY
INX
INC $0

LOOP EQU * ; 5 cycles per loop
DEY
BNE LOOP

DEX
BNE LOOP

DEC $0
BNE LOOP

RETURN RTS


* The fastest

INY
INX
INC $0 ; or INC for 65c02

LP EQU *
DEY
BNE LP
BEQ DOX

LOOP EQU *
DEY
DEY
DEY
DEY
DEY
DEY
DEY
DEY
DEY
DEY

DOX EQU *
DEX
BNE LOOP

DEC $0 ; or just DEC for 65c02
BNE LOOP

RETURN RTS
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