title Video driver routines for the KAYPRO-10  (C) 1983 By NLS.
.comment %
########################################################
##                                                    ##
##      KAYPRO 10 System                              ##
##                                                    ##
##      By M. Sherman                                 ##
##                                                    ##
##      Video driver routines for the KAYPRO-10       ##
##      and the 6545 video controller chip.           ##
##                                                    ##
##      Copyright (C) 1983 By Non-Linear Systems, Inc ##
##      No warranty is made, expressed or implied.    ##
##                                                    ##
########################################################
##      Date: 04/14/83                    [01]        ##
########################################################
%

; external variables
extrn	cursor, vrbase, crow, ccol, vatt, leadflg, vgb1
extrn	esccmd, row, row2, col, col2, vidram, ramlen, precur

; external routines
extrn	movsts, dltlin, inslin
extrn	pixon, pixoff, lineon, lineoff
extrn	kbdout

; routines for everyone else to use
public	vidout, vidinit, regrst, dtwait, clrdis, clreol, carret, putcur
public	getc, putc, getatt, putatt, print

.Z80

; conditional assembly equates

TRUE	equ	0ffffh
FALSE	equ	NOT TRUE

; video controller locations

vcbase	equ	1ch		; video controller base address
vccmd	equ	vcbase		; register select port
vcstat	equ	vcbase		; status port
vcrdat	equ	vcbase+1	; register data port
vcdata	equ	vcbase+3	; video controller data port

; command format, video controller commands:
; high byte = register to select, low byte = base addr. (register select)

curcmd	equ	0e1ch		; place cursor command
rwcmd	equ	121ch		; read/write command
strcmd	equ	01fh		; strobe, or "tickle", command
scrcmd	equ	0c1ch		; set start of display address command
				; ("scroll" command)
hiadd	equ	12h	; high byte register #, video mem. address,
loadd	equ	13h	; low byte register #, video mem. address.
cstart	equ	0ah	; cursor starting row count, cursor def. reg #
cstop	equ	0bh	; cursor ending row count.

csron	equ	60h	; cursor on, blinking at 1/32, starting row=0
csroff	equ	20h	; no cursor, starting row=0 (irrelevant)

; special character equates

space	equ	020h
nrmlatt	equ	00h

; single character control codes

belli	equ	07h	; bell code to video driver,
bello	equ	04h	; bell code to keyboard.
cr	equ	0dh	; carriage return
lf	equ	0ah	; line feed
ceol	equ	18h	; clear to end of line
ceos	equ	17h	; clear to end of screen
clrscr	equ	1ah	; clear screen
homec	equ	1eh	; home cursor
lcur	equ	08h	; left cursor (backspace)
rcur	equ	0ch	; right cursor (forespace)
ucur	equ	0bh	; up cursor
esc	equ	1bh	; escape code, initiates multi-
			; -character control sequences

; two-character commands

dline	equ	'R'	; delete line
iline	equ	'E'	; insert line

; three-character commands

atton	equ	'B'	; set attribute
attoff	equ	'C'	; clear attribute

; four-character commands

setpix	equ	'*'	; set pixel
clrpix	equ	' '	; clear pixel
lodcur	equ	'='	; load cursor address (cursor positioning)

; six-character commands

lindraw	equ	'L'	; draw a line
lineras	equ	'D'	; erase a line

; video driver equates

linesiz	equ	80		; characters per line
linesps	equ	24		; number of lines in the normal display
statlin	equ	linesps+1	; line number, status line
lastlin	equ	(linesps-1)*linesiz	; address, first chara last
					; normal display line
					; (the line above the status line)

;################################################
;#						#
;#		video drivers			#
;#						#
;################################################

	; clear to end of line
clreol:	call	caleol		; calculate end of line count
	jr	clrdis

	; clear to end of screen
clreos:	ld	c,linesps-1
	ld	a,(vatt)
	and	20h
	jr	nz,ceos22
	inc	c
ceos22:	ld	a,(crow)
	sub	c
	jr	nc,clreol	; clear to end of line if on last legal line
	neg			; two's complement, number of lines to erase
	ld	b,a
	ld	de,linesiz
	ld	hl,0
clresl:	add	hl,de
	djnz	clresl
	push	hl
	call	caleol
	pop	bc
	add	hl,bc		; total count in hl
	jr	clrdis		; do it

caleol:	ld	hl,linesiz
	ld	de,(cursor)
	ld	a,(ccol)
	ld	c,a
	xor	a		; clear a, clear flags (especially carry!)
	ld	b,a		; clear b
	sbc	hl,bc		; hl=number of bytes to move
	ret

vidinit:; Video hardware/software initialization routine.  Will set
	; video driver ram storage to reset/restart values,
	; reprogram the video controller chip,
	; clear the screen and place the cursor in the upper right corner.
	;
ramini:	ld	hl,vidram	; first, initialize the ram.
	ld	b,ramlen
	xor	a
rinilp:	ld	(hl),a
	inc	hl
	djnz	rinilp

ctrini:	ld	hl,ctrtbl	; then initialize the controller,
	ld	bc,ctblen*256+vcbase+1
	xor	a		; first register,=00
cinilp:	dec	c		; c:=base
	out	(c),a		; select register
	inc	a		; a:=register to program
	inc	c		; c:=data port
	outi			; (hl):=program data, out to (c)
	jr	nz,cinilp	; until b:=0
	ld	a,strcmd
	out	(vccmd),a	; start video chip processing.
	; fall through to clear screen
clear:	call	home		; home cursor
clear2:	ld	a,(vatt)
	and	0f0h		; clear ordinary attributes
	ld	(vatt),a	; clear attribute byte
	ld	de,(cursor)	; same as vrbase, now
	ld	hl,statlin*linesiz	; screen size
	and	20h
	jr	z,clrdis
	ld	hl,linesps*linesiz
	; fall through to clrdis...

clrdis:	; clear display and associated attributes.
	; de := start address, hl := number of locations to clear
	; all registers affected...
	;
	ld	bc,hiadd*100h+loadd
cdislp:	in	a,(vcstat)
	or	a
	jp	p,cdislp	; wait until ready,
	ld	a,b		; high address byte register number,
	out	(vccmd),a	; select it
	ld	a,d		; get high byte, new address,
	and	07h		; qualify address,
	ld	d,a		; put it back,
	out	(vcrdat),a	; output it.
	ld	a,c		; select
	out	(vccmd),a	; low address byte register,
	ld	a,e		; get low address byte,
	out	(vcrdat),a	; output it.
	ld	a,strcmd
	out	(vccmd),a	; start a new cycle,
cdislp3:in	a,(vcstat)	; wait until it's ready,
	or	a
	jp	p,cdislp3
	ld	a,20h		; clear data byte,
	out	(vcdata),a
	inc	de		; set up for attr., next byte
cdislp2:in	a,(vcstat)	; go do attributes
	or	a
	jp	p,cdislp2
	ld	a,b		; high address byte register number,
	out	(vccmd),a	; select it
	ld	a,d		; get high byte, new address,
	or	08h		; qualify address,
	out	(vcrdat),a	; output it.
	ld	a,c		; select
	out	(vccmd),a	; low address byte register,
	ld	a,e		; get low address byte,
	out	(vcrdat),a	; output it.
	ld	a,strcmd
	out	(vccmd),a	; start a new cycle,
cdislp4:in	a,(vcstat)	; wait until finished.
	or	a
	jp	p,cdislp4
	xor	a		; clear attribute byte
	out	(vcdata),a
	dec	hl
	ld	a,h
	or	l
	jr	nz,cdislp
	ret

home:	xor	a
	ld	(ccol),a	; reset column count
	ld	(crow),a	; reset row count
	ld	hl,(vrbase)
	ex	de,hl
	jp	putcur		; place cursor and exit

; video controller initialization table, currently for a 25 by 80 display.
;
ctrtbl:	db	6ah	; reg00 total char/sweep including retrace, clocks
	db	50h	; reg01 total displayed, cclks
	db	56h
	db	99h
	db	19h
	db	0ah
	db	19h
	db	19h
	db	78h
	db	0fh
	db	60h
	db	0fh
	db	00h
	db	00h
	db	00h
	db	00h
ctblen	equ	$-ctrtbl	; table length

; main entry point.

vidout:	ld	a,(leadflg)	; set by escape sequences
	or	a
	jp	nz,escseq	; an escape sequence is in progress
	ld	a,c
	or	a
	ret	z		; ignore nulls (requested by tech support)
	jp	m,vgmod		; video mode set? find out if negative (>80h)
	cp	space
	jp	c,spechar	; special characters
spcexe:	ld	a,c
	ld	de,(cursor)	; special character re-entry if non-control
	call	putc
	call	puta		; place attribute
vgmexe:	ld	a,(ccol)
	inc	a
	cp	linesiz
	jp	nc,crlf
	ld	(ccol),a		; save new count
	ld	de,(cursor)
	inc	de
	jp	putcur			; reposition cursor and exit

vgmod:	ld	a,(vatt)
	and	10h
	jr	z,spcexe	; not video graphics mode if not zero
	ld	a,(vgb1)
	and	40h
	jr	z,vgmod2
	ld	a,c
	and	01
	ld	(vgb1),a
	ret
vgmod2:	ld	a,(vgb1)
	or	a
	ld	a,c
	jr	z,vgmod5
	cpl
vgmod5:	or	80h
	ld	de,(cursor)
	call	putc
	ld	a,(vgb1)
	ld	c,a
	ld	a,(vatt)
	or	c
	call	putatt
	ld	a,40h
	ld	(vgb1),a	; set first
	jr	vgmexe

; move the cursor to the beginning of the line

carret:	ld	hl,(cursor)
	ld	a,(ccol)
	ld	e,a
	xor	a		; clear flags,a
	ld	d,a
	ld	(ccol),a	; reset line count to zero
	sbc	hl,de		; hl = beginning of line
	ex	de,hl		; de = beginning of line
	jr	putcur		; place cursor and exit

; crlf places the cursor at the beginning of the next line and sets the
; character column count, ccol, to zero.

crlf:	call	carret		; carriage return
	; fall through to linefeed...

; move the cursor down one line, scroll if necc.

linefd:	ld	a,(crow)	; character row count
	cp	linesps-1	; lines per screen
	jr	c,linef2	; not last line if carry,
	cp	statlin-1	; status line?
	ret	z		; if so, don't scroll
	call	scroll		; else is last line, scroll screen
	jr	linef3		; don't update character row count.

linef2:	inc	a		; update character row count,
	ld	(crow),a

linef3:	ld	hl,(cursor)	; move the cursor down one line.
	ld	de,linesiz
	add	hl,de
	ex	de,hl
	; fall through to putcur...

; place cursor, new cursor address in de
putcur:	ld	a,d
	and	07h
	ld	d,a
	ex	de,hl
	ld	(cursor),hl
	ld	bc,(vrbase)
	sbc	hl,bc
	jr	nc,putcr2
	ld	de,0800h
	add	hl,de
putcr2:	add	hl,bc
	ex	de,hl
	ld	bc,curcmd
	jp	regrst

upcur:	ld	a,(crow)
	cp	statlin-1
	ret	z		; no cursor up from status line,
	or	a
	ret	z		; or from top line
	dec	a
	ld	(crow),a	; update row count
	ld	hl,(cursor)
	ld	de,linesiz
	sbc	hl,de
	ex	de,hl		; put new value in de
	jr	putcur

lfcur:	ld	a,(ccol)
	or	a
	jr	nz,lcur2
	ld	a,(crow)
	or	a
	ret	z		; no way can do
	cp	statlin-1	; on status line?
	jr	z,lcur3
	dec	a
	ld	(crow),a	; update row count
	ld	a,linesiz
lcur2:	dec	a
	ld	(ccol),a	; update column count
	ld	de,(cursor)
	dec	de
	jr	putcur		; place and exit
lcur3:	ld	a,linesiz-1
	ld	(ccol),a	; going to the end of the line
	ld	hl,(cursor)
	ld	de,linesiz-1
	add	hl,de
	ex	de,hl
	jr	putcur

rtcur:	ld	a,(ccol)
	cp	linesiz-1
	jp	nc,crlf		; do a cr, do a lf if not status line
	ld	de,(cursor)
	inc	de
	inc	a
	ld	(ccol),a	; reset column count
	jr	putcur

scroll:	jp	movsts		; fast scroll

setatr:	ld	hl,vatt
	ld	a,c
	sub	30h
	jr	z,revid		; set reverse video on
	dec	a
	jr	z,redint	; set reduced intensity on
	dec	a
	jr	z,sblink	; set blinking on
	dec	a
	jr	z,sunlin	; set underlining on
	dec	a
	jr	z,setcur	; set cursor on
	dec	a
	jr	z,setvid	; set video mode on
	dec	a
	jr	z,savcur	; save current cursor location
	dec	a
	jr	z,savsts	; save contents of status line during scroll
	ret			; illegal, exit

; set attributes

revid:	ld	a,(hl)
	or	01h
	ld	(hl),a
	ret
redint:	ld	a,(hl)
	or	02h
	ld	(hl),a
	ret
sblink:	ld	a,(hl)
	or	04h
	ld	(hl),a
	ret
sunlin:	ld	a,(hl)
	or	08h
	ld	(hl),a
	ret
setcur:	ld	c,csron		; cursor on, 1/16 blink
setcr2:	ld	a,cstart	; cursor select register
	out	(vccmd),a
	ld	a,c
	out	(vcdata),a	; turn on cursor, 1/16 blink
	ret
setvid:	ld	a,(vatt)	; turn on video mode.
	or	10h		; (GB1,GB2 graphics pairs)
	ld	(vatt),a
	ld	a,40h
	ld	(vgb1),a
	ret

savcur:	ld	hl,(crow)	; save, or 'remember', current cursor position
	ld	(precur),hl
	ret

savsts:	ld	a,(vatt)	; turn on status line preservation,
	or	00100000b	; protect it from scrolling.
	ld	(vatt),a
	ret

; clear attributes

clratr:	ld	hl,vatt
	ld	a,c
	sub	30h
	jr	z,nrmvid	; set normal video on
	dec	a
	jr	z,nrmint	; set normal intensity on
	dec	a
	jr	z,cblink	; set blinking off
	dec	a
	jr	z,cunlin	; set underlining off
	dec	a
	jr	z,clrcur	; set cursor off
	dec	a
	jr	z,clrvid	; set video mode off
	dec	a
	jr	z,rstcur	; restore cursor to last loc.
	dec	a
	jr	z,scrsts	; scroll contents of status line during scroll
	ret			; illegal, exit

; clear attributes:

nrmvid:	ld	a,(hl)		; set to non-inverted display mode.
	and	11111110b
	ld	(hl),a
	ret
nrmint:	ld	a,(hl)		; set to normal intensity
	and	11111101b
	ld	(hl),a
	ret
cblink:	ld	a,(hl)		; set to no blinking.
	and	11111011b
	ld	(hl),a
	ret
cunlin:	ld	a,(hl)		; set to no underlining.
	and	11110111b
	ld	(hl),a
	ret
clrcur:	ld	c,csroff	; turn cursor off
	jr	setcr2
clrvid:	ld	a,(hl)		; turn off video mode
	and	11101111b
	ld	(hl),a
	ret
rstcur:	ld	hl,(precur)	; return cursor to last remembered location.
	ld	a,h		; ccol
	add	a,space
	ld	(col),a
	ld	a,l
	add	a,space
	ld	(row),a
	jp	curpos		; restore previously saved cursor
scrsts:	ld	a,(vatt)	; turn off status line preservation,
	and	11011111b	; scroll status line on scrolls
	ld	(vatt),a
	ret

; X,Y cursor positioning routine
;
curpos:	ld	hl,0
	ld	c,l	; set c to zero, too.
	ld	a,(row)
	sub	space
	ret	c	; error, exit
	ld	b,a
	jr	z,curpo3
	cp	statlin		; lines per screen
	ret	nc		; error, exit
	ld	de,linesiz
curpo2:	add	hl,de
	djnz	curpo2
curpo3:	ld	e,a	; save row count
	ld	a,(col)
	sub	 space
	ret	c	; error, exit
	cp	linesiz
	ret	nc	; error, exit
	ld	c,a
	ld	(ccol),a	; new column count
	ld	a,e
	ld	(crow),a	; new row count
	add	hl,bc
	ld	de,(vrbase)
	add	hl,de
	ex	de,hl
	jp	putcur		; place cursor

dtwait:	ld	bc,rwcmd
rgwait:	call	regrst
	dec	c		; return c to original value
	ld	a,strcmd	; tickle the dummy
	out	(c),a
rgwt2:	in	a,(c)
	or	a
	jp	p,rgwt2
	ret

regrst:	out	(c),b
	inc	c
	out	(c),d
	dec	c
	inc	b
	out	(c),b
	inc	c
	out	(c),e
	ret

getc:	ld	a,d
	and	07h
	ld	d,a
getc2:	call	dtwait
	in	a,(vcdata)
	ret

putc:	push	af	; save data
	ld	a,d
	and	07h
	ld	d,a
putc2:	call	dtwait
	pop	af
	out	(vcdata),a
	ret

puta:	ld	a,(vatt)	; video attribute
putatt:	push	hl		; save hl
	push	af
	call	addatt
	call	dtwait
	pop	af
	out	(vcdata),a
	ex	de,hl
	pop	hl
	ret

getatt:	push	hl
	call	addatt
	call	getc2
	ex	de,hl
	pop	hl
	ret

addatt:	ld	hl,801h		; video attribute offset
	add	hl,de
	ld	a,h
	and	07h		; 00000000 to 00000111
	or	08h		; 00001000 to 00001111
	ld	h,a
	ex	de,hl
	ret

escseq:	ld	hl,leadflg
	ld	(hl),0		; clear flag
	cp	1
	jr	nz,esc2
	ld	a,c
	and	07fh
	cp	dline		; delete line?
	jp	z,dltlin
	cp	iline		; insert line?
	jp	z,inslin
	cp	'A'		; Kaypro-II display lower case?
	ret	z		; yes, ignore
	cp	'G'		; Kaypro-II display greek?
	ret	z		; yes, ignore
	ld	(esccmd),a	; set command
	ld	(hl),2
	ret

esc2:	cp	2
	jr	nz,esc3
	ld	a,(esccmd)
	cp	atton
	jp	z,setatr	; set attribute command
	cp	attoff
	jp	z,clratr	; clear attribute
	ld	a,c
	ld	(row),a
	ld	(hl),3
	ret

esc3:	cp	3
	jr	nz,esc4
	ld	a,c
	ld	(col),a
	ld	a,(esccmd)
	cp	lodcur
	jp	z,curpos	; cursor positioning
	cp	setpix
	jp	z,pixon		; pixel on
	cp	clrpix
	jp	z,pixoff	; pixel off
	ld	(hl),4
	ret
esc4:	cp	4
	jr	nz,esc5
	ld	a,c
	ld	(row2),a
	ld	(hl),5
	ret
esc5:	ld	a,c
	ld	(col2),a
	ld	a,(esccmd)
	cp	lindraw
	jp	z,lineon
	cp	lineras
	jp	z,lineoff
	ret			; illegal command, exit.

bell:	ld	c,bello		; put keyboard bell chara in c reg.,
	jp	kbdout		; ring bell

spechar:cp	cr
	jp	z,carret	; carriage return
	cp	lf
	jp	z,linefd	; line feed
	cp	belli
	jr	z,bell		; bell
	cp	ceol
	jp	z,clreol	; clear to end of line
	cp	ceos
	jp	z,clreos	; clear to end of screen
	cp	clrscr
	jp	z,clear		; clear screen
	cp	lcur
	jp	z,lfcur		; left cursor
	cp	rcur
	jp	z,rtcur		; right cursor
	cp	ucur
	jp	z,upcur		; up cursor
	cp	homec
	jp	z,home		; home cursor
	cp	esc
	jp	nz,spcexe	; not a control character, write it
	ld	a,1
	ld	(leadflg),a	; set escape in progress
	ret

; print routine

print:	pop	hl
	ld	a,(hl)
	inc	hl
	push	hl
	or	a
	ret	z
	ld	c,a
	call	vidout
	jr	print

	defw	0000h

END