;***************************************************************;
;								;
;		VIS50A  TERMINAL UNIT ROUTINE			;
;****************************************************************
;*								*
;*                  Alpha Base Modified                        *
;*                                                              *
;****************************************************************
;
;
;
	SEARCH	SYS
	SEARCH	TRM			; Terminal Service Equates (octal).
	OBJNAM	.TDV
	RADIX	16			; Hex used throughout.

; Equates of non-printing ASCII chars used in this driver.
BS	=08				; backspace
TAB	=09				; (horizontal) tab
CR	=0D				; carriage-return
LF	=0A				; line-feed
CTRL.U	=15				; ^U
ESC	=1B				; escape
ES$	=9B				; escape with bit-7 on
SPACE	=20				; space
RUB	=7F				; rubout
SEMI	=3B				; semicolon
NULL	=00				; null

PARITY	=80				; added to char to set parity bit
CNTRL	=40				; subtracted to make control char
ESCON=^H4000				; esc found bit
$CTLA	=^H01				; control a
$BS	=^H08				; backspace
$TAB	=^H09				; tab
$LF	=^H0A				; line- feed
$VT	=^H0B				; vertical tab
$FF	=^H0C				; right- arrow, formfeed
$CR	=^H0D				; carriage return
$CTLU	=^H15				; control u
$CTLZ	=^H1A				; control z
$ESC	=^H1B				; escape char
$SPACE	=^H20
$COMMA	=^H2C				; comma
$SEMC	=^H3B				; semicolon
$LB	=^H3C				; <
$RUB	=^H7F				; rubout
BIT7	=^H80				; set bit 7
$CTLA7	=1+BIT7				; ^A- don't strip first
$CR7	=$CR+BIT7			; carriage return
$ESC7	=$ESC+BIT7			; escape with bit7 set
CTLMSK	=^H1F				; for masking to control chars


;*****************************************************************************
;
;	CONFIGURING THIS DRIVER
;
;*****************************************************************************

	PAGE
;*****************************************************************************
;
; Terminal Definition Area
;
;*****************************************************************************

LINE	=	24.			; Lines/page (screen height).
COLUMN	=	80.			; Columns/line (screen width).

VIS50A:	WORD	^O2000			; NEW FORMAT DRIVER
	RTN;	JIN			; Input Routine
	BR	JOUT			; Output Routine
	BR	ECHO			; Echo Routine
	BR	CRT.			; Crt Control
	RTN;	INIT			; Initialization routine
	WORD	IMPSIZ			; Impure zone size
	BYTE	LINE,COLUMN		; Screen dimensions
	WORD	B0.15			; Bitmap showing
	WORD	B16.31			;  which TCRT functions
	WORD	B32.47			;  are implemented.
	WORD	B48.63			; 
	WORD	B64.79			; 


; Correct out-of-range branches.
;JIN:	JMP	INPUT
CRT.:	JMP	CRT
JOUT:	JMP	OUTPUT
	PAGE

; TCRT bitmap equates:
B0.15	=	^B0111111111111111	; Rightmost (low-order) bit is bit 0.
B16.31	=	^B0000000000000000	;
B32.47	=	^B0000000000000000	; 
B48.63	=	^B0000000000000000	; 
B64.79	=	^B0000000000000000	; 
FUNCS	=	80.			; Size of bitmap, in bits.

; Impure area (storage allocated to the terminal at system init time).
; Equates relative to (A0).
ESCNT=   0				; esc chr skip counter
ESCNT2=  1 
ISTATE	=	0			; Input state (see equates at INPUT).
TFLAGS	=	2			; Terminal state (flags: see below).
ATTRIB	=	4			; Display attributes (see below).
HILOSW	=	4			; set intensity sw
LSTLIN	=	5
OSTATE	=	6
O.CNT=		8
G0SW=		9
XYPTR=		0A

IMPSIZ	=	10.			; Impure area size.

; Terminal hardware state.
	PAGE
INIT:
;*****************************************************************************
; This routine is called once at system initialization time.
; The impure area is initialized here.
;*****************************************************************************
;	MOV	T.IMP(A5),A0		; Find impure area.
;	CLRW	OSTATE(A0)
;	MOV	#I.INIT,ISTATE(A0)	; Set input state to initial state.
	RTN



;*	ECHO	*
;****************
; Special echo processing is done here
; Rubouts will backspace and erase the previous character
; Control-U will erase the entire line by backspacing and erasing
ECHO:	CMP	D1,#$CTLU		; Control-U
	JEQ	CTRLU
	CMP	D1,#$RUB			; Rubout
	JNE	ECHX

; Rubouts are handled by the old backspace-and-erase game
; D6ecial handling must be performed if we are rubbing out a tab
; R3 contains the character being rubbed out
RUBOUT: CMP	D3,#$TAB		; Was it a TAB?
	BEQ	RBTB			;	Yes
; Rubout was of a printable character - Queue up the backspace sequence
KRTG:	MOV	#3,D3			; Set character count
	LEA	A6,ERUB			; Set buffer address
	MOV	A6,D1
	TRMBFQ				; Queue the backspace sequence
	RTN
ERUB:	BYTE	$BS,$SPACE,$BS,0
; Rubout was of a TAB - we must calculate how big the TAB was and backup over it
RBTB:	CLR	D3
	MOVW	T.POB(A5),D3		; Set beginning position count
	MOV	T.ICC(A5),D2		; Set input character count
	MOV	T.IBF(A5),A6		; Set input buffer base
KRTS:	DEC	D2			; Done with scan?
	BMI	KRTQ			;	Yes
	MOVB	(A6)+,D1		; Scan forward calculating position
	CMP	D1,#$TAB
	BEQ	KRTT
	CMP	D1,#$CR
	BEQ	KRTC
	CMP	D1,#$ESC
	BEQ	KRTI
	CMP	D1,#$SPACE		;	Control-Char
	BLO	KRTS
	CMP	D1,#'y			; why doesn't it check for { | }  ??
	BHI	KRTS
KRTI:	INC	D3			; Increment position for one character
	BR	KRTS
KRTT:	ADD	#10,D3			; Adjust position for TAB
	AND	#~7,D3
	BR	KRTS
KRTC:	CLR	D3			; Clear position for CR
	BR	KRTS
KRTQ:	COM	D3			; Calculate necessary backspaces
	AND	#7,D3
	INC	D3
	MOV	#10,D1			; Set immediate backspace character
	TRMBFQ				; Queue the backspaces
ECHX:	RTN

; Echo a CONTROL-U by erasing the entire line
CTRLU:	TST	D6			; No action if nothing to erase
	BEQ	CTUX
	CLR	D3
	MOVW	T.POO(A5),D3		; Calculate backspace number to erase THE LINE
	SUBW	T.POB(A5),D3
	BEQ	ECHX	

	CMP	D3,T.ILS(A5)		; Insure not greater than terminal width
	BLOS	CLUA
	MOV	T.ILS(A5),D3
CLUA:	MOV	#$BS,D1			; Queue up backspaces
	TRMBFQ
	ASL	D1,#2
	TRMBFQ
	MOV	#$BS,D1
	TRMBFQ
	
CTUX:	RTN

	PAGE

;------------------- OUTPUT ROUTINE

 	RADIX 8
OUTPUT:					; routine to override tll950
 	MOV	T.IMP(A5),A0
 	TSTB	ESCNT(A0)			; Alpha base codes
 	JNE	NOOUT
	BIT	#ESCON,@A0		; esc sequence?
	BNE	TSTSEQ
	CMPB	D1,#^H1B		; esc ?
	BNE	OUTX
	BIS	#ESCON,@A0
OUTX:
	LCC	#10
	RTN
TSTSEQ:
	ANDW	#~ESCON,@A0		; clear the indicator
	CMPB	D1,#'=			; cursor?
	BEQ	OUTX			; yes go to it
	CMPB	D1,#'.
	BEQ	SETSKP
	CMPB	D1,#'f			; line 25 msg?
	JEQ	SET24
	CMPB	D1,#'|			; set function
	BEQ	SETSK3
	CMPB	D1,#'J			; clr eos?
	BEQ	SETNUL
	CMPB	D1,#'*			; clr scrn?
	BNE	1$
	LEA	A6,CRTCLR+1
 	MOV	#300.,D3
	BR	DOINS

1$:
	CMPB	D1,#'G			; attribute?
	BNE	2$
	MOVB	#2,ESCNT(A0)
	BR	SETSK2

2$:	LEA	A2,OT.TAB		; CHK THE REST
3$:	TSTB	@A2			; end
	BEQ	OUTX
	CMPB	D1,(A2)+		; Eq?
	BEQ	4$
	INC	A2
	BR	3$
4$:	MOVB	@A2,D1
 	BIT	#^H80,D1		; sleep needed?
 	BEQ	OUTX
	LEA	A6,CLREOS
	MOVI	3,D3
	BR	DOINS

SETSKP:	MOVB	#1,ESCNT(A0)		; set count to 1
SETSK2:	MOVB	#'6,D1			; fake out
	BR	OUTX
SETSK3:	MOVB	#7,ESCNT(A0)
	BR	SETSK2

SETNUL:	LEA	A0,T.OQX(A5)
	QINS	A0
	CLR	(A0)+
	MOV	#330.,(A0)+
	LEA	A2,CRTNUL
SETADR:	MOV	A2,@A0
	JMP	OUTX
	
SET24:
	LEA	A6,POS24
	MOVI	3,D3
;	SETB	ESCNT2(A0)		; SET TO KILL NEXT EREOL
DOINS:
	MOV	A6,D1
	LEA	A0,T.OQX(A5)
	QINS	A0
	CLR	(A0)+
	MOV	D3,(A0)+		; length
	MOV	D1,@A0
	LCC	#4
	CLR	D1
	RTN

	
NOOUT:	CMPB	ESCNT(A0),#7
	BNE	NOOUTS
	CMPB	D1,#^H19			; ^Y
	BEQ	NOOUTC
	CLR	D1
	LCC	#4
	RTN
NOOUTC:	CLRW	ESCNT(A0)
NOOUTE:	CLR	D1
NOOUTF:	CLRB	ESCNT(A0)
	LCC	#4
	RTN
NOOUTS:
	CMPB	ESCNT(A0),#2		; ^G?
	BNE	NOOUTE
	MOVB	#40,D1
	BR	NOOUTF
POS24:	BYTE	'=,'7,40 ;,33,50		;		^H18,01
CLREOS:	BYTE	'k,33,'J
	EVEN

  	RADIX	8
;********************
;*	 CRT	    *
;********************
;SPECIAL CRT CONTROL PROCESSING
;D1 CONTAINS THE CONTROL CODE FOR X,T POSITIONING OR SPECIAL COMMANDS
;IF D1 IS POSITIVE WE HAVE SCREEN POSITIONING (ROW IN HI BYTE, COL IN LO BYTE)
;IF D1 IS NEGATIVE WE HAVE THE SPECIAL COMMAND IN THE LOW BYTE
CRT:	TSTW	D1		;IS IT CURSOR POSITION?
	BMI	CRTS		;  NO
;CURSOR POSITIONING - D1 CONTAINS X,Y COORDINATES
	TTYI			;SEND POSITION COMMAND
	BYTE	233,75,0,0
	ADDW	#17437,D1	;ADD POSITION OFFSETS
	SWAB	D1		;SEND ROW FIRST
	TTY
	SWAB	D1		;SEND COLUMN SECOND
	TTY
	RTN
;SPECIAL COMMANDS - D1 CONTAINS THE COMMAND CODE IN THE LOW BYTE
CRTS:	MOVB	D1,D1		;STRIP THE HIGH BYTE
	BNE	CRTU		;  AND BRANCH UNLESS CLEAR SCREEN
	TTYL	CRTCLR		;SPECIAL CASE FOR CLEAR SCREEN
	RTN

;COMMAND PROCESSING PER DIRECTOR TABLES
CRTU:	CMPB	D1,#CRCB-CRCA	;CHECK FOR VALID CODE
	BHI	CRTX		;  AND BYPASS IF BAD
	PUSH	A2
	LEA	A2,CRCA-1	;INDEX THE TABLE
	CLR	D7
	MOVB	D1,D7
	ADD	D7,A2		;ADD COMMAND CODE
	MOVB	@A2,D7		;PICK UP DATA FIELD OFFSET
	ADD	D7,A2		;MAKE ABSOLUTE DATA ADDRESS
	TTYL	@A2		;PRINT THE DATA FIELD
	POP	A2
	CMPB	D1,#10.
	BNE	CRTX
CRTZ:	TTYL	CRTNUL
CRTX:	RTN


;Null characters for long commands
CRTCLR:	BYTE	233,'T,233,'s,233,'v,^H1A
CRTNUL:	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE 	200,200,200,200,200,200,200,200,200,200,200,200,200,200,200
	BYTE	200,200,200,200,200,200,200,200,0
	EVEN

;BYTE OFFSET AND DATA TABLES FOLLOW FOR ALL COMMANDS
CRCA:	BYTE	C1-.,C2-.,C3-.,C4-.,C5-.,C6-.,C7-.,C8-.
	BYTE	C9-.,C10-.,C11-.,C12-.,C13-.,C14-.
CRCB:
C1:	BYTE	233,'H,0	;CURSOR HOME
C2:	BYTE	215,0		;CURSOR RETURN
C3:	BYTE	13,0		;CURSOR UP
C4:	BYTE	12,0		;CURSOR DOWN
C5:	BYTE	10,0		;CURSOR LEFT
C6:	BYTE	14,0		;CURSOR RIGHT
C7:	BYTE	233,43,0	;LOCK KEYBOARD
C8:	BYTE	233,42,0,0	;UNLOCK KEYBOARD
C10:	BYTE	233,'k,233,'J,0	;ERASE TO END OF SCREEN
C11:	BYTE	233,'U,0	;PROTECT FIELD
C12:	BYTE	233,'T,0	;UNPROTECT FIELD
C13:	BYTE	233,'q,0	;ENABLE PROTECTED FIELDS
C14:	BYTE	233,'s,0	;DISABLE PROTECTED FIELDS
C9:	BYTE	233,'K,0	;ERASE TO END OF LINE
	EVEN

OT.TAB:

	BYTE	'(,'T			; protect off 
	BYTE	'),'U			; protect on
	BYTE	'','s			; protect mode off
	BYTE	'&,'q			; protect mode on
	BYTE	'T,'K  			; clr eol
	BYTE	'Y,^H80			; clr eos
	BYTE	0
	EVEN
	END


.