cc65/libsrc/atari/cputc.s

;
; Mark Keates, Christian Groessler
;
; void cputcxy (unsigned char x, unsigned char y, char c);
; void cputc (char c);
;

    	.export	       	_cputcxy, _cputc
	.export		plot, cputdirect, putchar
	.import		popa, _gotoxy, mul40
	.importzp	tmp4,ptr4
	.import		_revflag

	.include	"atari.inc"

_cputcxy:
	pha	    		; Save C
	jsr	popa		; Get Y
	jsr	_gotoxy		; Set cursor, drop x
	pla			; Restore C

_cputc:
	cmp	#$0D		; CR
	bne	L4
	lda	#0
	sta	COLCRS
	beq	plot		; return
	
L4:	cmp	#$0A		; LF
	beq	newline
	cmp	#ATEOL 	  	; Atari-EOL?
	beq	newline

	tay
	rol	a
	rol	a
	rol	a
	rol	a
	and	#3
	tax
	tya
	and	#$9f
	ora	ataint,x

cputdirect:			; accepts screen code
	jsr	putchar
	
; advance cursor
	inc	COLCRS
	lda	COLCRS
	cmp	#40
	bcc	plot
	lda	#0
	sta	COLCRS

	.export newline
newline:
	inc	ROWCRS
	lda	ROWCRS
	cmp	#24
	bne	plot
	lda	#0
	sta	ROWCRS
plot:	ldy	COLCRS
	ldx	ROWCRS
	rts

putchar:
	pha			; save char
	lda	ROWCRS
	jsr	mul40
L3:	clc
	adc	SAVMSC		; add start of screen memory
	sta	ptr4
	lda	tmp4
	adc	SAVMSC+1
	sta	ptr4+1
	pla			; get char again
	ora	_revflag
	ldy	COLCRS
	sta	(ptr4),y
	rts

	.rodata
ataint:	.byte	64,0,32,96