base:1x1_scroll
Simple 1×1 Scroller with variable speed and forward/backward scrolling. Turbo-Assembler syntax.
*= $1000
jsr scrinit
sei
lda #>irq
sta $0315
lda #<irq
sta $0314
lda #$1b
sta $d011
lda #$01
sta $d01a
lda #$7f
sta $dc0d
lda #$70
sta $d012
cli
rts
irq
lda scrpos
sta $d016
inc $d020
lda #$80
lp .var *
cmp $d012
bne lp
inc $d020
jsr scroll
dec $d020
dec $d020
lda #$c8
sta $d016
inc $d019
jmp $ea31
;---------------------------------------
;scroller v1 (w) gpz of hitmen
;---------------------------------------
;features : unlimited text-length
; (end with $00)
;
; 8 different speeds
; (select with $f8 to $ff)
;
; ascii-text (enter in the
; source-code !)
;
; forward & backward-scroll !
; (select with $f1/$f0)
;---------------------------------------
;$d016-val. : in scrpos
;scroll-init : jsr scrinit
;irq-drive : jsr scroll
;---------------------------------------
line = $0540
;---------------------------------------
scrinit lda #>scrtxt ; textstart
sta txtpos+2
lda #<scrtxt
sta txtpos+1
lda #$01 ; speed 1
sta fscrspd+1
sta bscrspd+1
lda #$07
sta scrpos
lda #$01 ; forward
sta scrdir
rts
scroll lda scrdir
cmp #$01 ; forward ?
bne backward ; no !
forward lda scrpos
sec
fscrspd sbc #$01
and #$07
sta scrpos
bcc fver
rts
fver ldx #$00
flp1 lda line+1,x
sta line,x
inx
cpx #$27
bne flp1
jmp txtpos
backward lda scrpos
and #$07
clc
bscrspd adc #$01
tax
and #$07
sta scrpos
txa
adc #$f8
bcs bver
rts
bver ldx #$26
blp1 lda line,x
sta line+1,x
dex
cpx #$ff
bne blp1
txtpos lda $dead ;
cmp #$00 ; end of txt ?
bne lp2 ; no !
lda #>scrtxt
sta txtpos+2
lda #<scrtxt
sta txtpos+1
jmp txtpos
lp2 cmp #$f8 ; speedbyte ?
bcc lp4 ; no !
and #$07
clc
adc #$01
sta fscrspd+1
sta bscrspd+1
jmp txtcount
lp4 cmp #$f1 ; dir. forw ?
bcc lp6 ; no !
ldx #$01
stx scrdir
jmp txtcount
lp6 cmp #$f0 ; dir. back ?
bcc lp5 ; no !
ldx #$00
stx scrdir
jmp txtcount
lp5 ldx scrdir
cpx #$01 ; forward ?
bne back ; no !
and #$3f
sta line+$27
lda scrpos
clc
adc #$08
and #$07
sta scrpos
jmp txtcount
back and #$3f
sta line
lda scrpos
sec
sbc #$08
and #$07
sta scrpos
txtcount inc txtpos+1
bne lp3
inc txtpos+2
lp3
ende rts
scrdir .byte $01
scrpos .byte $07
scrtxt
.byte $f1,$f8
.text "speed 1 "
.byte $f9
.text "speed 2 "
.byte $fa
.text "speed 3 "
.byte $fb
.text "speed 4 "
.byte $fc
.text "speed 5 "
.byte $fd
.text "speed 6 "
.byte $fe
.text "speed 7 "
.byte $ff
.text "speed 8 "
.byte $f0,$f8
.text "1 deeps "
.byte $f9
.text "2 deeps "
.byte $fa
.text "3 deeps "
.byte $fb
.text "4 deeps "
.byte $fc
.text "5 deeps "
.byte $fd
.text "6 deeps "
.byte $fe
.text "7 deeps "
.byte $ff
.text "8 deeps "
.byte $00
base/1x1_scroll.txt · Last modified: 2015-04-17 04:30 by 127.0.0.1