SBTTL 'Control Character Routines (20_Nov_84)'
	PAGE
;======================================================================
;
;	Copyright 1984
;	Morrow Designs, Inc.
;	San Leandro, Ca.
;
;----------------------------------------------------------------------
; Index (12_Nov_84)
;------------------
;
;	BELL	Bell Code
;	BS	BackSpace
;	TAB	Tab
;	LF	Line Feed
;	US	Up Space
;	FS	ForeSpace
;	CR	Carriage Return
;	CLRSCR	Clear Screen
;	ESC	Escape
;	HOME	Home
;	NEWLIN	NewLine (Carriage Return Line Feed)
	PAGE

;----------------------------------------------------------------------
; Ring the Bell
;--------------
;
BELL:	LDX	BAUD
	BPL	BLSK1		;nothing from keyboard, so beep.

	JSR	GETKEY		;else, get the key from keyboard before beeping
	JMP	BELL		;wait for settle 

BLSK1:	LDA	#BEEP		;BEEP! BEEP!
	JMP	KBRDOUT

;----------------------------------------------------------------------
; BackSpace
;----------
;
BS:	LDX	COLMN
	LDY	ROW		;get the current row
	DEX
	BPL	BSSK1		;if on same line, branch

	LDX	#79		;else, set last column of line above
	DEY
	BPL	BSSK1

	LDY	#0
	LDX	#0
BSSK1:	STX	COLMN
	STY	ROW
	JMP	SETCUR

;----------------------------------------------------------------------
; Tab
;----
;
TAB:	LDA	COLMN		;tab over 8 spaces
	AND	#$F8
	CLC
	ADC	#8
	CMP	#80
	BNE	TABSK1

	LDA	#0
	STA	COLMN
	JMP	LF
	
TABSK1:	STA	COLMN
	JMP	SETCUR
	PAGE

;----------------------------------------------------------------------
; Line Feed
;----------
;
LF:	LDA	ROW		;Line feed
	CMP	#23		;check if scroll req'd
	BEQ	LFSK1		;if yes, then scroll

	INC	ROW		;else, just set new row
	JMP	SETCUR		;and put the cursor there

LFSK1:	SEI			;Scroll screen
	LDA	SCBASE
	CLC
	ADC	#80
	STA	SCBASE
	LDA	SCBASE+1	;new scbase = old scbase + 80
	ADC	#0
	AND	#%111		;wrap it around
	STA	SCBASE+1
	JSR	SETCUR		;set cursor register of CRTC
	LDX	#13
	LDA	SCBASE		;set starting reg of CRTC
	STX	CRTC
	STA	CRTC+1
	DEX
	LDA	SCBASE+1
	STX	CRTC
	STA	CRTC+1
	CLI
	JMP	CLRLIN

;----------------------------------------------------------------------
; UpSpace
;--------
;
US:	DEC	ROW		;Up a line
	BPL	USSK1

	LDA	#0
	STA	ROW
USSK1:	JMP	SETCUR
	PAGE

;----------------------------------------------------------------------
; ForeSpace
;----------
;
FS:	LDX	COLMN		;forespace
	LDY	ROW
	INX
	CPX	#80
	BCC	FSSK1

	LDX	#0
	INY
	CPY	#24
	BCC	FSSK1

	LDY	#23
	LDX	#79 
FSSK1:	STX	COLMN
	STY	ROW
	JMP	SETCUR

;----------------------------------------------------------------------
; Carriage Return
;----------------
;
CR:	LDA	#0		;Carriage return
	STA	COLMN
	JMP	SETPOS
	PAGE

;----------------------------------------------------------------------
; Clear Screen (26_Nov_84)
;-------------------------
;
CLRSCR:	LDA	#HIGH CRAM	;init start of ARAM and CRAM
	STA	CHARD+1
	LDA	#HIGH ARAM
	STA	ATTRD+1

	LDY	#0
	STY	CHARD
	STY	ATTRD

	LDX	#8		;X:= Page Counter
CLCLP1:	LDA	CLRCHAR		;Repeat	A:= Character to clear CRAM to
CLCLP2:	STA	(CHARD),Y	;	Repeat	Clear a Location
	INY			;		Increment the Index
	BNE	CLCLP2		;	Until (Index wraps around)

	LDA	ATTTAB+0	;	A:= Normal Video Attribute
CLCLP3:	STA	(ATTRD),Y	;	Repeat	Clear a location
	INY			;		Increment the Index
	BNE	CLCLP3		;	Until (Index wraps around)

	INC	CHARD+1		;	Increment the Page Pointer
	INC	ATTRD+1		;	Increment the Page Pointer
	DEX			;Until (8 pages have been cleared)
	BNE	CLCLP1
	JMP	HOME		;Home the Cursor

;----------------------------------------------------------------------
; Escape Recieved
;----------------
;
ESC:	LDA	#1		;escape handler
	STA	NSEQ		;set up to save next char
	LDA	#LOW ESCHAND	;routine to handle next char
	STA	CODE
	LDA	#HIGH ESCHAND
	STA	CODE+1
	RTS
	PAGE

;----------------------------------------------------------------------
; Home the Cursor
;----------------
;
HOME:	LDA	#0		;put cursor in home position
	STA	ROW		;ROW = COLMN = 0
	STA	COLMN
	JMP	SETCUR		;set new cursor position

;----------------------------------------------------------------------
; Print a Carriage Return followed by a Line Feed
;------------------------------------------------
;
NEWLIN:	JSR	CR		;carriage return line feed
	JMP	LF

;----------------------------------------------------------------------
; Keyboard Lock/UnLock
;---------------------
;
;UNLOCK:LDA	#$0
;	STA	LOCKMD		; re-enable keyboard interrupts
;	LDA	#LOCKOFF	; turn off keyboard lock LED
;	JMP	KBRDOUT
;
;LOCK:	LDA	#$FF
;	STA	LOCKMD		; set keyboard lock mode
;	LDA	#LOCKON		; turn on keyboard lock LED
;	JMP	KBRDOUT

	END