.z80

;		  Copyright (C), 1982
;		 Digital Research, Inc
;		     P.O. Box 579
;		Pacific Grove, CA  93950

;   This is the invariant portion of the modular BIOS and is
;	distributed as source for informational purposes only.
;	All desired modifications should be performed by
;	adding or changing externally defined modules.
;	This allows producing "standard" I/O modules that
;	can be combined to support a particular system
;	configuration.
;
;   Modified for faster character I/O by Udo Munk

cr	equ	13
lf	equ	10
bell	equ	7
ctlQ	equ	'Q'-'@'
ctlS	equ	'S'-'@'

	cseg			; GENCPM puts CSEG stuff in common memory

	; variables in system data page

;;	extrn	@covec,@civec,@aovec,@aivec,@lovec ; I/O redirection vectors
				
	; user defined character I/O routines

	extrn	?ci,?co,?cist,?cost	; each take device in <B>
	extrn	?cinit			; (re)initialize device in <C>
	extrn	@ctbl			; physical character device table


	include	modebaud.inc	; define mode bits


	public	@covec,@civec,@aovec,@aivec,@lovec ; I/O redirection vectors
	public	?const,?conin,?cono,?list,?auxo,?auxi
	public	?lists,?conos,?auxis,?auxos,?dvtbl,charini


@CIVEC:	dw	0		; Console Input Redirection
				; Vector (word, r/w)
@COVEC:	dw	0		; Console Output Redirection
				; Vector (word, r/w)
@AIVEC:	dw	0		; Auxiliary Input Redirection
				; Vector (word, r/w)
@AOVEC:	dw	0		; Auxiliary Output Redirection
				; Vector (word, r/w)
@LOVEC:	dw	0		; List Output Redirection
				; Vector (word, r/w)


charini:

	ld	c,15		; initialize all 16 character devices
c$init$loop:
	push	bc
	call	?cinit
	pop	bc
	dec	c
	jp	p,c$init$loop

;	ld	hl,1000000000000000b	; assign console to HOST
	ld	hl,0010000000000000b	; assign console to ASCI1
	ld	(@civec),hl
	ld	(@covec),hl
	ld	hl,0000000000000000b	; assign auxiliary to nothing
	ld	(@aivec),hl
	ld	(@aovec),hl
	ld	hl,0000000000000000b	; assign printer to nothing
	ld	(@lovec),hl
	ret


	; DEVTBL
	;	Return address of character device table

?dvtbl:
devtbl:
	ld	hl,@ctbl
	ret


	; CONOUT
	;	Console Output. Send character in <C>
	;			to all selected devices

?cono:
conout:
	ld	hl,(@covec)	; fetch console output bit vector
	jr	out$scan


	; AUXOUT
	;	Auxiliary Output. Send character in <C>
	;			to all selected devices

?auxo:
auxout:
	ld	hl,(@aovec)	; fetch aux output bit vector
	jr	out$scan


	; LIST
	;	List Output. Send character in <C>
	;			to all selected devices.

?list:
list:
	ld	hl,(@lovec)	; fetch list output bit vector

out$scan:
	ld	b,0		; start with device 0
co$next:
	add	hl,hl		; shift out next bit
	jr	nc,not$out$device
	push	hl		; save the vector
	push	bc		; save the count and character
	call	?co		; if device selected, print it
	pop	bc		; recover count and character
	pop	hl		; recover the rest of the vector
not$out$device:
	inc	b		; next device number
	ld	a,h
	or	l		; see if any devices left
	jr	nz,co$next	; and go find them...
	ret


	; CONOST
	;	Console Output Status. Return true if
	;		all selected console output devices
	;		are ready.

?conos:
conost:
	ld	hl,(@covec)	; get console output bit vector
	jr	ost$scan


	; AUXOST
	;	Auxiliary Output Status. Return true if
	;		all selected auxiliary output devices
	;		are ready.

?auxos:
auxost:
	ld	hl,(@aovec)	; get aux output bit vector
	jr	ost$scan


	; LISTST
	;	List Output Status. Return true if
	;		all selected list output devices
	;		are ready.

?lists:
listst:
	ld	hl,(@lovec)	; get list output bit vector

ost$scan:
	ld	b,0		; start with device 0
cos$next:
	add	hl,hl		; check next bit
	push	hl		; save the vector
	push	bc		; save the count
	ld	a,0FFh		; assume device ready
	call	c,coster	; check status for this device
	pop	bc		; recover count
	pop	hl		; recover bit vector
	or	a		; see if device ready
	ret	z		; if any not ready, return false
	inc	b		; drop device number
	ld	a,h
	or	l		; see if any more selected devices
	jr	nz,cos$next
	or	0FFh		; all selected were ready, return true
	ret

coster:		; check for output device ready, including optional
		;	xon/xoff support
		;
		;TODO: interrupt driven devices should xon/xoff handle
		;	in isv

	ld	l,b
	ld	h,0		; make device code 16 bits
	push	hl		; save it in stack
	add	hl,hl
	add	hl,hl
	add	hl,hl		; create offset into device characteristics tbl
	ld	de,@ctbl+6
	add	hl,de		; make address of mode byte
	ld	a,(hl)
	and	mb$xon$xoff
	pop	hl		; recover console number in <HL>
	jp	z,?cost		; not a xon device, go get output status direct
	ld	de,xofflist
	add	hl,de		; make pointer to proper xon/xoff flag
	call	cist1		; see if this keyboard has character
	ld	a,(hl)
	call	nz,ci1		; get flag or read key if any
	cp	ctlq
	jr	nz,not$q	; if its a ctl-Q,
	ld	a,0FFh		;	set the flag ready
not$q:
	cp	ctls
	jr	nz,not$s	; if its a ctl-S,
	ld	a,00h		;	clear the flag
not$s:
	ld	(hl),a		; save the flag
	call	cost1		; get the actual output status,
	and	(hl)		; and mask with ctl-Q/ctl-S flag
	ret			; return this as the status

cist1:		; get input status with <BC> and <HL> saved
	push	bc
	push	hl
	call	?cist
	pop	hl
	pop	bc
	or	a
	ret

cost1:		; get output status, saving <BC> & <HL>
	push	bc
	push	hl
	call	?cost
	pop	hl
	pop	bc
	or	a
	ret

ci1:		; get input, saving <BC> & <HL>
	push	bc
	push	hl
	call	?ci
	pop	hl
	pop	bc
	ret


	; AUXIST
	;	Auxiliary Input Status. Return true if
	;		any selected auxiliary input device
	;		has an available character.
?auxis:
auxist:
	ld	hl,(@aivec)	; get aux input bit vector
	jr	ist$scan


	; CONST
	;	Console Input Status. Return true if
	;		any selected console input device
	;		has an available character.
?const:
const:
	ld	hl,(@civec)	; get console input bit vector


ist$scan:
	ld	b,0		; start with device 0
cis$next:
	add	hl,hl		; check next bit
	ld	a,0		; assume device not ready
	call	c,cist1		; check status for this device
	or	a
	ret	nz		; if any ready, return true
	inc	b		; next device number
	ld	a,h
	or	l		; see if any more selected devices
	jr	nz,cis$next
	xor	a		; all selected were not ready, return false
	ret


	; AUXIN
	;	Auxiliary Input. Return character from first
	;		ready auxiliary input device.
?auxi:
auxin:
	ld	hl,(@aivec)
	jr	in$scan


	; CONIN
	;	Console Input. Return character from first
	;		ready console input device.
?conin:
conin:
	ld	hl,(@civec)

in$scan:
	push	hl		; save bit vector
	ld	b,0
ci$next:
	add	hl,hl		; shift out next bit
	ld	a,0		; insure zero a (nonexistant device not ready).
	call	c,cist1		; see if the device has a character
	or	a
	jr	nz,ci$rdy	; this device has a character
	inc	b		; else, next device
	ld	a,h
	or	l		; see if any more devices
	jr	nz,ci$next	; go look at them
	pop	hl		; recover bit vector
	jr	in$scan		; loop til we find a character
ci$rdy:
	pop	hl		; discard extra stack
	jp	?ci



xofflist:
	db 	-1,-1,-1,-1,-1,-1,-1,-1	; ctl-s clears to zero
	db	-1,-1,-1,-1,-1,-1,-1,-1


	end