2018-09-28 17:05:11 +00:00
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; Copyright 2018 faddenSoft. All Rights Reserved.
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; See the LICENSE.txt file for distribution terms (Apache 2.0).
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;
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; Assembler: Merlin 32
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org $1000
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clc
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xce
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sep #$ff ;set all flags
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mx %11
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; clear individual flags with instructions
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; (this has no effect on the assembled output, but you can see the
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; effects on the "status" column in the display list)
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clv
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cld
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cli
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clc
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lda #$80 ;clear Z
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lda #$01 ;clear N
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sed
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sei
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sec
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lda #$ff ;set N
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adc #$00 ;set V, Z (actually scrambles NVZC)
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; clear individual flags with REP
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sep #$ff
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rep #$80
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rep #$40
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rep #$20
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rep #$10
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rep #$08
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rep #$04
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rep #$02
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rep #$01
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; exercise SEP/REP with #$00
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sep #$00
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sep #$ff
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rep #$00
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rep #$ff
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; confirm emulation behavior
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mx %00 ;long regs
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lda #$feed ;check it
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sec
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xce ;emulation mode
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lda #$ff ;check it
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rep #$30 ;should have no effect...
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mx %11 ;...but Merlin32 doesn't know that
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lda #$ff
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clc
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xce ;back to native, should set M/X=1
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lda #$ff ;check it
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; try one long, one short
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rep #$20 ;long a
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sep #$10 ;short x/y
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mx %01
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lda #$0000
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ldx #$01
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ldy #$02
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sep #$20 ;short a
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rep #$10 ;long x/y
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mx %10
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lda #$01
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ldx #$0000
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ldy #$0000
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; check branch instructions; NVMXDIZC
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sep #$30
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mx %11
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lda #$00
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pha
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plp ;without a nearby PHP, flags will be scrambled
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rep #$80
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bpl ok_bpl
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brk $00
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ok_bpl sep #$80
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bpl :bad ;branch never taken
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bmi ok_bmi
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:bad brk $00
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ok_bmi rep #$40
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bvc ok_bvc
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brk $00
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ok_bvc sep #$40
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bvs ok_bvs
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brk $00
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ok_bvs rep #$01
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bcc ok_bcc
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brk $00
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ok_bcc sep #$01
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bcs ok_bcs
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brk $00
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ok_bcs rep #$02
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bne ok_bne
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brk $00
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ok_bne sep #$02
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beq ok_beq
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brk $00
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ok_beq
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; check NZ flags set by immediate load
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sep #$ff ;set all
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mx %11
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lda #$01
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bne ok_nzero
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brk $db
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ok_nzero
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lda #$00
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beq ok_zero
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brk $db
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ok_zero
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bpl ok_pos
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brk $db
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ok_pos
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lda #$80
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bmi ok_neg
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brk $db
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ok_neg
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; check NZ flags set by immediate AND
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lda #$ff
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and #$00
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beq ok_andZ1
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brk $db
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ok_andZ1
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lda #$00
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and #$ff
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beq ok_andZ1A
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brk $db
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ok_andZ1A
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lda #$ff
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and #$7f
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bne ok_andZ0
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brk $db
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ok_andZ0
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bpl ok_andN0
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brk $db
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ok_andN0
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lda #$ff
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and #$80
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bmi ok_andN1
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brk $db
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ok_andN1
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; check NZ flags set by immediate ORA
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lda #$00
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ora #$00
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beq ok_oraZ1
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brk $db
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ok_oraZ1
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ora #$01
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bne ok_oraZ0
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brk $db
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ok_oraZ0
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lda #$00
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ora #$7f
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bpl ok_oraN0
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brk $db
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ok_oraN0
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ora #$80
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bmi ok_oraN1
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brk $db
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ok_oraN1
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2018-10-09 19:27:47 +00:00
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; check rol/ror
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:foo lda :foo ;scramble N/V
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sec
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ror A ;rotates the carry into the hi bit (N)
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bmi ok_ror1
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brk $dc
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ok_ror1
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clc
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ror A ;now try with carry clear
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bpl ok_ror2
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brk $dc
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ok_ror2
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lda #$00 ;set Z=1
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sec
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rol A ;set Z=0 (could also set C=0)
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bne ok_rol1
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brk $dc
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ok_rol1
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2018-09-28 17:05:11 +00:00
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; simple php/plp pair test
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clc
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php
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sec
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plp ;should restore cleared carry
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bcc ok_plp
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brk $00
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ok_plp
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rep #$20 ;long a
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sep #$10 ;short x/y
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mx %01
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jsr long_subr ;confirm flag propagation
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rep #$30
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mx %00
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jsr ambig_subr
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sep #$30
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mx %11
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jsr ambig_subr
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rep #$20 ;long a
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sep #$10 ;short x/y
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mx %01
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jsr long_subr ;call it again
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; leave the main routine with short flags set
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sep #$30
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mx %11
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rts
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; only called with longm/shortx
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mx %01
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long_subr
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lda #$1234
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ldx #$ff
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rts
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; this is called with different values for M/X, so it defaults to short
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mx %11
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ambig_subr
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lda #$ff
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ldx #$ee
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ldy #$dd
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rts
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