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;
;	Mode-driven console I/O package
; 	Adapted from Steve Ward's CIO.C
;	9/82 by Leor Zolman
;
; This package provides a mode-driven direct console interface for applications
; where the standard library versions of "getchar", "putchar", etc.,
; do not provide enough control. The console I/O mode is set by calling the
; funciton "ttymode", where each bit of the argument controls a specific
; feature of the I/O mechanism, as follows:
;	--------------------------------------------------------------
;BIT:	ø7, 6 ø     5	 ø     4    ø 3     ø    2   ø   1   ø  0    ø
;	ø     ø swap CR &ø  LF -->  østrip  ø  x-on/ ø quit  ø echo  ø
; USE:	ønot  ø and LF   ø   CR-LF  øbit 7  ø  x-off ø char  ø mode  ø
;	ø usedø (input)  ø (output) ø(input)ø(output)ø(input)ø(input)ø
;	--------------------------------------------------------------
;
; Most features are self-explanatory; the "quit char" bit, if on, means
; that if the user types the standard system "Quit" character (set to
; control-C by default in the run-time package, and changeable by poking
; into the appropriate location), then program execution will be terminated
; and control will return to command level.
;
; Functions in this source file:
;
;	putchar	getchar	kbhit	ttymode
;
; "putchar", "getchar" and "kbhit" have the same calling format as the standard
; library versions. "ttymode" takes a new mode byte based on the diagram above,
; and returns the previous mode byte.
;

	INCLUDE <bds.lib>

NL:	equ 10
CR:	equ 0dh


;
; putchar(c)
;
	FUNCTION	putchar
	EXTERNAL	rawio

	call	ma1toh	;get C in HL
	push	h	;pass to rawio
	lxi	h,1	;pass "putchar" code to rawio
	push	h
	call	rawio	;put out the char
	pop	d
	pop	d
	ret

	ENDFUNC

;
; int getchar()
;

	FUNCTION	getchar
	EXTERNAL	rawio

	lxi	h,2
	push	h	;pass "getchar" code to rawio
	call	rawio
	pop	d
	ret

	ENDFUNC

;
; int kbhit()
;

	FUNCTION	kbhit
	EXTERNAL	rawio

	lxi	h,3
	push	h	;pass "kbhit" code to rawio
	call	rawio
	pop	d
	ret

	ENDFUNC

;
; int ttymode(newmode)
;

	FUNCTION	ttymode
	EXTERNAL	rawio

	call	ma1toh	;get mode value
	push	h	;pass to rawio
	lxi	h,4
	push	h	;pass "ttymode" code to rawio
	call	rawio
	pop	d
	pop	d
	ret

	ENDFUNC

	FUNCTION	rawio
	EXTERNAL	exit
	call	arghak	;get arg1 = operation code, arg2 = arg
	push	b
again:	call	istat	;check input status
	jz	brk	;any input? if not, go away
	mov	c,a	;yes... put in C
	lda	mode	;save current mode
	mov	b,a	;save mode in B
	ani	strip	;stripping parity?
	mov	a,c
	jz	rawio0
	ani	7fh	;if so, strip parity
rawio0:	mov	c,a	;and save for now.
	mov	a,b	;get mode again
	ani	swap	;swapping CR and LF?
	jz	rawio1

	mov	a,c	;is it CR?
	cpi	CR
	mvi	c,LF
	jz	rawio1	;if so, turn into LF
	cpi	LF	;is it LF?
	mvi	c,CR
	jz	rawio1	;if so, turn into CR
	mov	c,a	;otherwise leave it alone	

rawio1:	mov	a,b	;look at mode
	ani	quit	;allowing quit characters?
	jz	rawio2	;if not, don't check for quitc

;
;  Check for quits:
;

	lda	quitc	;else do...
	cmp	c	;char a quit char?
	jz	exit	;if so, get out of here!
rawio2:	mov	a,b	;look at mode
	ani	flow	;recognizing flow control?
	jz	rawio5

;
;  Handle Flow Control:
;

	mov	a,c	;look at char
	cpi	'S'-64	;control-S?
	jnz	rawio4
rawio3:	sta	freeze	;if so, freeze things
	jmp	brk
rawio4:	cpi	'Q'-64	;control-Q?
	jnz	rawio5
	xra	a	;if so, turn off freeze
	jmp	rawio3	

;
; Save the char and echo if echo mode is on:
;

rawio5:	lda	pending
	ora	a	;any chars already stacked up?
	jnz	brk	;if so, ignore new character
	inr	a	;set pending flag
	sta	pending
	mov	a,c	;get the char
	sta	pendch	;save it
	mov	a,b	;echo mode?
	ani	echo
	cnz	putraw	;if so, put out the character
		
brk:
	lda	arg1	;look at control code
	ora	a	;null op?
	jz	done	;if so, go return

	dcr	a	;putchar?
	jnz	brk3
	lda	freeze	;if frozen,
	ora	a
	jnz	again	;don't try to write till we get ^Q
	
;
; Put out a character to console:
;

	lda	arg2	;get the arg to putchar
	mov	c,a	;write it to console
	call	putraw

;
; Check for newline expansion:
;

	cpi	NL	;'Øn'?
	jnz	brk2
	lda	mode
	ani	expand	;expanding newlines?
	jz	brk2
	mvi	c,CR		
	call	putraw	;put out CR if so
brk2:	lhld	arg2	;return the arg
done:	pop	b	;restore BC
	ret

brk3:	dcr	a	;getchar?
	jnz	brk4
			;yes.
	lda	pending	;any pending input?
	ora	a
	jz	again	;if not, go poll input
	xra	a	;else clear pending input flag
	sta	pending
	lda	pendch	;and return the char
brk3a:	mov	l,a
	mvi	h,0
	pop	b
	ret

brk4:	dcr	a	;kbhit?
	jnz	brk5
	lda	pending	;yes. return pending status.
	jmp	brk3a

brk5:	dcr	a	;set I/O mode?
	jnz	done	;if not, don't do nuthin at all
	lda	mode	;get mode
	mov	l,a	;save old mode in L
	lda	arg2	;get new mode
	sta	mode	;set it
	ani	flow	;check if flow control is enabled
	jnz	brk6	;if it is, don't touch state
	sta	freeze	;else make sure we're thawed by clearing freeze
brk6:	mvi	h,0	;clear HL	
	pop	b
	ret	

istat:	mvi	c,dconio	;prepare for direct console I/O BDOS call
	mvi	e,0FFh		;interrogate console status
	call	bdos
	ora 	a		;set Z if no char ready
	ret

putraw:	push	b
	push	d
	push	psw
	mov	e,c		;put char in E
	mvi	c,dconio
	call	bdos
	pop	psw
	pop	d
	pop	b
	ret
	
ch:	ds 1
oldmode: ds 1

	ENDFUNC

	end
«eof»
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