;;
	;; This file is part of "VirtuaMUnstaz Demo Distribution".
	;;
	;; This is free software; you can redistribute it and/or modify
	;; it under the terms of the GNU General Public License as published by
	;; the Free Software Foundation; either version 2, or (at your option)
	;; any later version.
	;;
	;; "VirtuaMUnstaz Demo Distribution" is distributed in the hope that it will be
	;; useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
	;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	;; GNU General Public License for more details.
	;;
	;; You should have received a copy of the GNU General Public License
	;; along with this software; see the file COPYING.  If not, write to the
	;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	;; Boston, MA 02111-1307, USA.
	;;

	;;
	;; scroll.s
	;;
	;; version 0.5
	;;
	;; by <vmu@mud.de>
	;; 
	;; Need aslc86k v1.3+ to assemble this.
	;;
	
	.include "sfr.i"


index = $32
time0 = $37
time1 = $38
ixbnk = $33
ptrbackup = $36
startptr = $34
count = $35
scrollbuffer = $3b
; - $41
			
	;; Reset and interrupt vectors
	
	.org	0

	jmpf	start

	.org	$3

	jmp	nop_irq

	.org	$b

	jmp	nop_irq
	
	.org	$13

	jmp	nop_irq

	.org	$1b

	jmp	t1int
	
	.org	$23

	jmp	nop_irq

	.org	$2b

	jmp	nop_irq
	
	.org	$33

	jmp	nop_irq

	.org	$3b

	jmp	nop_irq

	.org	$43

	jmp	nop_irq

	.org	$4b

	clr1	p3int,0
	clr1	p3int,1
nop_irq:
	reti


	.org	$130
t1int:
	push	ie
	clr1	ie,7
	not1	ext,0
	jmpf	t1int
	pop	ie
	reti

		
	.org	$1f0
goodbye:	
	not1	ext,0
	jmpf	goodbye

        .include "header.i"

	;; Main program

	.org	$680

start:
	mov #$a1,ocr
	mov #$09,mcr
	mov #$80,vccr
	clr1 p3int,0
	clr1 p1,7
	mov #$ff,p3

	call clrscr

	call loadlogo
waitstart:
	call getkeys
	and #$30
	bnz waitstart


	mov #1,xbnk
	mov #$80+16+6,2
	mov #$80+16*7+5,3
	call drawline_double

	mov #0,index

	mov #0,c
	mov #<font,trl 	
	mov #>font,trh
	mov #scrollbuffer,1
        call set_scrollbuffer	; offset to char is in c	
	
charloop:
	mov #0,c	; loop 8 times over (scroll one bit left)

endless:
	mov #scrollbuffer,1

	mov #$80+5+16*3,2	; start drawinf position

	
	mov #0,b	; loop over 8 lines in screen 
line:			
	ld @R1		; load data from scrollbuffer in acc
	call scrollline
	st @R1

	inc 1	; scrollbuffer next byte
	ld 2	; next screen line
	add #6
	st 2

	ld @R1
	call scrollline
	st @R1

	inc 1
	ld 2
	add #10
	st 2

	inc b
	ld b
	bne #4, line
	
	call waitloop

	inc c
	ld c
	bne #8, endless	; after we scrolled 8 times 1 bit left
			; we have to insert a new char in
			; scrollbuffer



	call getkeys	

	; get next char from scrolltext	

	; we are using a pointer to the scrolltext in index
	; suprisingly this works although the pointer range
	; exceeds 256
	
	mov #<text,trl
	mov #>text,trh
	ld index
	add #1
	st index
	ldc
	bnz skip	; zero byte ? 

	; set pointers back to beginning of
	; scrolltext
	mov #<text,trl
	mov #>text,trh
	mov #0,acc
	st index
	ldc
skip:
	sub #1
	add acc		; ACC = ACC * 8 (*8=*2*2*2)
	add acc
	add acc
	st c		; char offset is now in c

	mov #<font,trl 	
	mov #>font,trh
	mov #scrollbuffer,1
        call set_scrollbuffer	; offset to char is in c	
	
	br charloop
	
getkeys:
	bp p7,0,quit
	ld p3
	bn acc,6,quit
	bn acc,7,sleep
	ret

quit:
	jmp goodbye
	
sleep:
	bn p3,7,sleep	; Wait for SLEEP to be depressed
	mov #0,vccr	; Blank LCD
sleepmore:
	set1 pcon,0	; Enter HALT mode
	bp p7,0,quit	; Docked?
	bp p3,7,sleepmore	; No SLEEP press yet
	mov #$80,vccr	; Reenable LCD
waitsleepup:
	bn p3,7,waitsleepup
	br getkeys

waitloop:
	push c
	push acc
	mov #$50,c
.wloop:
	dec c
	ld c
	bnz .wloop

	pop acc
	pop c
	ret
	
waitloop2:
	; not used
	; can be used to wait longer than waitloop
	
	mov #$1,time1
.extwloop:
	mov #$FF,time0
.intwloop:
	dbnz time0,.intwloop
	dbnz time1,.extwloop
	ret

drawline_double:
	; draws two lines from the left to the right
	; linestart 1: R2
	; linestart 2: R3
	
	push 2
	push 3
	push c
	push b
	
	mov #0,b
outerloop:
	mov #0,c
innerloop:
	ld @R2
	set1 PSW,7
	rorc
	st @R2
	ld @R3
	set1 PSW,7
	rolc
	st @R3

	call waitloop

	inc c
	ld c
	bne #8,innerloop
	
	inc 2
	dec 3
	inc b
	ld b
	bne #6,outerloop

	pop b
	pop c
	pop 3
	pop 2
	ret
	

scrollline:
	; scroll 6 bytes at once without loop
	; because of performance considerations

	clr1 ocr,5
	push 2
	
	rolc		; scroll input line from scrollbuffer one bit
	push acc	; to the left and store it then
			; (so it's already complete for next line)
	
	ld @R2
	rolc
	st @R2
	dec 2

	ld @R2
	rolc
	st @R2
	dec 2

	ld @R2
	rolc
	st @R2
	dec 2
	
	ld @R2
	rolc
	st @R2
	dec 2

	ld @R2
	rolc
	st @R2
	dec 2

	ld @R2
	rolc
	st @R2

	pop acc
	pop 2

	set1 ocr,5
	ret

set_scrollbuffer:	
	; will copy a new char to the scrollbuffer
	; from the font pixel data buffer
	; 1 scrollbuffer
	; c offset
	; trh, trl pointer to chardata
	push 1
	push b
	push c

	xor acc
	st b
bufferloop:	
	ld c
	ldc 
	st @R1
	inc 1
	
	inc c
	inc b
	ld b
	bne #8,bufferloop
	
	pop c
	pop b
	pop 1
	ret

clrscr:	
	; clears the LCD screen
	; from marcus
	clr1 ocr,5
	push acc
	push xbnk
	push 2
	mov #0,xbnk
.cbank:	mov #$80,2
.cloop:	mov #$00,@R2
	inc 2
	ld 2
	and #$f
	bne #$c,.cskip
	ld 2
	add #4
	st 2
.cskip:	ld 2
	bnz .cloop
	bp xbnk,0,.cexit
	mov #1,xbnk
	br .cbank
.cexit:	pop 2
	pop xbnk
	pop acc
	set1 ocr,5
	ret

loadlogo:
	; copies data to LCD screen
	clr1 ocr,5
	push acc
	push xbnk
	push c
	push b
	push 2

	mov #>logo,trh
	mov #<logo,trl

	mov #$80,startptr
	mov #32,count
	
	mov #0,ptrbackup
oloop:
	ld ixbnk
	st xbnk

	ld startptr
	st 2
	ld count
	st b
	

	ld 2
	and #$f
	bnz evenline

iloop:
	ld ptrbackup
	st c

;	ld c
	ldc
	st @R2
	inc 2
	inc c
	
	ld c
	ldc
	st @R2
	inc 2
	inc c

	ld c
	ldc
	st @R2
	inc 2
	inc c
	
	ld c
	ldc
	st @R2
	inc 2
	inc c

	ld c
	ldc
	st @R2
	inc 2
	inc c

	ld c
	ldc
	st @R2
	inc 2
	inc c

	dec b
evenline:
	ld ptrbackup
	st c

; next line the same
;	ld c
	ldc
	st @R2
	inc 2
	inc c
	
	ld c
	ldc
	st @R2
	inc 2
	inc c

	ld c
	ldc
	st @R2
	inc 2
	inc c
	
	ld c
	ldc
	st @R2
	inc 2
	inc c

	ld c
	ldc
	st @R2
	inc 2
	inc c

	ld c
	ldc
	st @R2
	inc 2
	inc c
	
	ld 2
	add #4
	st 2

	bnz .sskip
	inc xbnk
	mov #$80,2
.sskip:	
	dec b
	ld b
	bnz iloop  ; draw 8 double lines     
	
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop
	call waitloop

	ld startptr
	and #$f
	bz .sskip2
	ld startptr
	add #4
	st startptr
.sskip2: 
	ld startptr
	add #6
	st startptr
	bnz .sskip3
	mov #$80,startptr
	inc ixbnk
.sskip3: ld ptrbackup
	add #6
	st ptrbackup

	dec count
	ld count
	bz lexit
	jmp oloop
lexit:
	pop 2
	pop b
	pop c
	pop xbnk
	pop acc
	set1 ocr,5

	ret

	.include "text.i"
logo:
	.include "logo.i"
	.include "pad.i"
	.cnop	0,$200		; pad to an even number of blocks