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rollingdemo
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rollingdemo/scrollingtext.s

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DSK SCROLL
**************************************************
* To Do:
*
**************************************************
* Variables
**************************************************
CHAR EQU $FC ; char/pixel to plot
TEXTSCROLL1 EQU $06 ; which note to play
TEXTSCROLL2 EQU $04 ; duration of note
TEXTSCROLL3 EQU $05 ; frequency/interclick delay
TEXTSCROLL4 EQU $03 ; ASCII "wave" progress/offset
TEXTSCROLL5 EQU $02 ; "instructions" string offset
TEXTSCROLL6 EQU $00
TEXTSCROLL7 EQU $01
TEXTSCROLL8 EQU $07 ; scrolling text offset pixels
TEXTSCROLLEND EQU $08 ; textscroll + #$28
**************************************************
* Apple Standard Memory Locations
**************************************************
CLRLORES EQU $F832
LORES EQU $C050
TXTSET EQU $C051
MIXCLR EQU $C052
MIXSET EQU $C053
TXTPAGE1 EQU $C054
TXTPAGE2 EQU $C055
KEY EQU $C000
C80STOREOFF EQU $C000
C80STOREON EQU $C001
STROBE EQU $C010
SPEAKER EQU $C030
VBL EQU $C02E
RDVBLBAR EQU $C019 ;not VBL (VBL signal low
WAIT EQU $FCA8
RAMWRTAUX EQU $C005
RAMWRTMAIN EQU $C004
SETAN3 EQU $C05E ;Set annunciator-3 output to 0
SET80VID EQU $C00D ;enable 80-column display mode (WR-only)
HOME EQU $FC58 ; clear the text screen
CH EQU $24 ; cursor Horiz
CV EQU $25 ; cursor Vert
VTAB EQU $FC22 ; Sets the cursor vertical position (from CV)
COUT EQU $FDED ; Calls the output routine whose address is stored in CSW,
; normally COUTI
STROUT EQU $DB3A ;Y=String ptr high, A=String ptr low
ALTTEXT EQU $C055
ALTTEXTOFF EQU $C054
ROMINIT EQU $FB2F
ROMSETKBD EQU $FE89
ROMSETVID EQU $FE93
ALTCHAR EQU $C00F ; enables alternative character set - mousetext
BLINK EQU $F3
ORG $2000 ; PROGRAM DATA STARTS AT $2000
**************************************************
* START - sets up various fiddly zero page bits
**************************************************
LDA #$00 ; reset the string and wave offsets for drawing text
STA CHAR
LDA #$32
STA TEXTSCROLL1
STA TEXTSCROLL2
STA TEXTSCROLL3
STA TEXTSCROLL4
STA TEXTSCROLL5
STA TEXTSCROLL6
STA TEXTSCROLL7
STA TEXTSCROLL8
LDA #$33
STA TEXTSCROLLEND
DRAWBOARD JSR HOME ; clears the main text screen
STA LORES
JSR FILLSCREENFAST
MAINLOOP
JSR SCROLLINGTEXT
JMP MAINLOOP
* put scrolling text at $528,$5a8 40 pixels at a time, offset by TEXTSCROLL
SCROLLINGTEXT
LDY TEXTSCROLL1
LDX #$00
SCROLLTEXT LDA SCROLLING,Y
STA $400,X
LDA SCROLLING2,Y
STA $480,X
INY
INX
TXA
CMP #$28
BCC SCROLLTEXT ; draw 40 characters across
INC TEXTSCROLL1 ; increment offset for next pass
LDA TEXTSCROLL1 ; compare offset to 50
CMP TEXTSCROLLEND
BEQ SETUPTEXT2
RTS ; return if less than 50 iterations.
SETUPTEXT2 LDA #$00
STA TEXTSCROLL1 ; reset offset if over 50
INC TEXTSCROLL2 ; increment next scroller's offset
LDY TEXTSCROLL2
LDX #$00
SCROLLTEXT2 LDA SCROLLING,Y
CLC
ADC #$11
STA $600,X
LDA SCROLLING2,Y
CLC
ADC #$11
STA $680,X
INY
INX
TXA
CMP #$28
BCC SCROLLTEXT2
LDA TEXTSCROLL2 ; compare offset to 50
CMP TEXTSCROLLEND
BEQ SETUPTEXT3
RTS
SETUPTEXT3 LDA #$00
STA TEXTSCROLL2 ; reset offset if over 50
INC TEXTSCROLL3 ; increment next scroller's offset
LDY TEXTSCROLL3
LDX #$00
SCROLLTEXT3 LDA SCROLLING,Y
CLC
ADC #$22
STA $428,X
LDA SCROLLING2,Y
CLC
ADC #$22
STA $4a8,X
INY
INX
TXA
CMP #$28
BCC SCROLLTEXT3
LDA TEXTSCROLL3 ; compare offset to 50
CMP TEXTSCROLLEND
BEQ SETUPTEXT4
RTS
SETUPTEXT4 LDA #$00
STA TEXTSCROLL3 ; reset offset if over 50
INC TEXTSCROLL4 ; increment next scroller's offset
LDY TEXTSCROLL4
LDX #$00
SCROLLTEXT4 LDA SCROLLING,Y
CLC
ADC #$33
STA $628,X
LDA SCROLLING2,Y
CLC
ADC #$33
STA $6a8,X
INY
INX
TXA
CMP #$28
BCC SCROLLTEXT4
LDA TEXTSCROLL4 ; compare offset to 50
CMP TEXTSCROLLEND
BEQ SETUPTEXT5
RTS
SETUPTEXT5 LDA #$00
STA TEXTSCROLL4 ; reset offset if over 50
INC TEXTSCROLL5 ; increment next scroller's offset
LDY TEXTSCROLL5
LDX #$00
SCROLLTEXT5 LDA SCROLLING,Y
CLC
ADC #$44
STA $450,X
LDA SCROLLING2,Y
CLC
ADC #$44
STA $4d0,X
INY
INX
TXA
CMP #$28
BCC SCROLLTEXT5
LDA TEXTSCROLL5 ; compare offset to 50
CMP TEXTSCROLLEND
BEQ SETUPTEXT6
RTS
SETUPTEXT6 LDA #$00
STA TEXTSCROLL5 ; reset offset if over 50
INC TEXTSCROLL6 ; increment next scroller's offset
LDY TEXTSCROLL6
LDX #$00
SCROLLTEXT6 LDA SCROLLING,Y
CLC
ADC #$55
STA $650,X
LDA SCROLLING2,Y
CLC
ADC #$55
STA $6d0,X
INY
INX
TXA
CMP #$28
BCC SCROLLTEXT6
LDA TEXTSCROLL6 ; compare offset to 50
CMP TEXTSCROLLEND
BEQ SETUPTEXT7
RTS
SETUPTEXT7 LDA #$00
STA TEXTSCROLL6 ; reset offset if over 50
RTS
**************************************************
* blanks the screen quickly.
* https://www.atarimagazines.com/compute/issue10/032_1_THE_APPLE_GAZETTE.php
**************************************************
FILLSCREENFAST ; 6023 instructions
FLASH LDA CHAR ; Get selected color byte
LDY #$78 ; #$78 Prepare to fill 120 bytes
JSR FILL1 ; Fill four sets of 120 bytes each
LDY #$78 ; Prepare to fill 80 bytes
JSR FILL2 ; Fill four sets of 80 bytes each
RTS ; Done. Return.
FILL1 DEY
STA $400, Y
STA $480, Y
STA $500, Y
STA $580, Y
BNE FILL1
RTS
FILL2 DEY
STA $600, Y
STA $680, Y
STA $700, Y
STA $780, Y
BNE FILL2
RTS
**************************************************
SCROLLING HEX 55,05,00,55,05,05,00,55,05,55,00,55,05,55,00,55,00,00,00,55,00,00,00,55,00,55,05,55,00,55,05,05,00,00,05,55,05,00,55,05,05,00,05,50,05,00,05,55,05,00,00,55,05,00,55,05,05,00,55,05,55,00,55,05,55,00,55,00,00,00,55,00,00,00,55,00,55,05,55,00,55,05,05,00,00,05,55,05,00,55,05,05,00,05,50,05,00,05,55,05,00,00
SCROLLING2 HEX 50,55,00,55,50,50,00,55,05,50,00,55,50,55,00,55,50,50,00,55,50,50,00,55,00,55,00,55,00,55,50,55,00,00,00,55,00,00,55,55,50,00,50,05,50,00,00,55,00,00,00,50,55,00,55,50,50,00,55,05,50,00,55,50,55,00,55,50,50,00,55,50,50,00,55,00,55,00,55,00,55,50,55,00,00,00,55,00,00,55,55,50,00,50,05,50,00,00,55,00,00,00
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