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6502bench/SourceGen/Examples/Tutorial/Source/Tutorial2.S
Andy McFadden 4b46b78e34 Rearrange the tutorial files
Copied the extension script tutorial files out of the Scripts
directory and into the Tutorial directory.  This makes more sense,
and makes it possible to expand the script sample without altering
the tutorial.

Reverted the Scripts sample to be an actual sample, rather than a
tutorial.

Renumbered the last two tutorials and added them to the ToC.  This
gives them actual numbers rather than treating them as add-ons to
the advanced tutorial.

Moved the source files for the tutorial binaries into a subdirectory
to reduce clutter.

This does mean we have two separate copies of the inline string
sample plugins, but that's an artifact of our attempts at security.
2019-10-30 09:49:11 -07:00

115 lines
2.1 KiB
ArmAsm

; Copyright 2018 faddenSoft. All Rights Reserved.
; See the LICENSE.txt file for distribution terms (Apache 2.0).
;
; Assembler: Merlin 32
INPUT equ $3000
OUTPUT equ $0400
PTR1 equ $02
PTR2 equ $04
START equ $2000
org START-2
dw START
sec
ror A
bmi skipstr
string0 asc 'first string',00
string1 asc 'another string',00
string2 asc 'string the third',00
string3 asc 'last string',00
skipstr
lda #<stringtab
sta PTR1
lda #>stringtab
sta PTR1+1
jsr thing
and #$03
asl A
tay
lda (PTR1),y
sta PTR2
iny
lda (PTR1),y
sta PTR2+1
ldy #$ff
]loop iny
lda (PTR2),y
beq copydone
ora #$80
sta OUTPUT,y
bne ]loop ;always taken
stringtab
dw string0
dw string1
dw string2
dw string3
copydone
jsr PrintInlineZString
asc 'Embedded!',00
lda #$ff ;self-modifying code example
sta _mod+1
_mod lda #$00
bne skipbrk
middat ds 4
outdat ds 1
skipbrk
lda middat ;nearby-label example
ora middat+1
and middat+2
eor middat+3
ldx #$00 ;embedded instruction example
dfb $2c
rebr ldx #$01
sta outdat
lda INPUT
lsr A
lsr A
lsr A
lsr A
sta INPUT
bne rebr
rts
thing
lda INPUT
rts
PrintInlineZString
pla
sta PTR1
pla
sta PTR1+1
ldy #$01
:loop lda (PTR1),Y
beq strend
ora #$80
jsr $FDED
iny
bne :loop
strend tya
clc
adc PTR1
sta PTR1
lda PTR1+1
adc #$00
pha
lda PTR1
pha
rts