cc65/libsrc/c128/cputc.s

;
; Ullrich von Bassewitz, 2000-08-06, 2002-12-21
; Using lots of code from MagerValp, MagerValp@cling.gu.se
;
; void cputcxy (unsigned char x, unsigned char y, char c);
; void cputc (char c);
;

    	.export	     	_cputcxy, _cputc, cputdirect, putchar
 	.export	     	newline, plot
        .constructor    initcputc
        .destructor     donecputc
 	.import	     	popa, _gotoxy
        .import         PLOT

 	.include     	"c128.inc"

cputdirect      = PRINT
newline         = NEWLINE


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

; Plot a character - also used as internal function

_cputc: cmp    	#$0A   		; CR?
       	beq	cr     		; Output a cr

 	cmp	#$0D   	  	; LF?
       	bne	L2
       	jmp     NEWLINE		; Update cursor position

; Printable char of some sort

L2:	cmp	#' '
       	bcc    	L4              ; Other control char
    	tay
    	bmi	L5
    	cmp	#$60
    	bcc	L3
    	and	#$DF
    	bne    	L4              ; Branch always
L3: 	and	#$3F
L4:     jmp     PRINT  		; Output character

; Handle character if high bit set

L5:	and	#$7F
       	cmp    	#$7E  	  	; PI?
  	bne	L6
  	lda	#$5E  	  	; Load screen code for PI
  	bne    	L4
L6:	ora	#$40
  	bne	L4              ; Branch always

; Carriage return

cr:	lda	#0
    	sta	CURS_X

; Set cursor position, calculate RAM pointers

plot:	ldy	CURS_X
	ldx	CURS_Y
	clc
	jmp	PLOT  		; Set the new cursor

; Write one character to the screen without doing anything else, return X
; position in Y

putchar	= $CC2F

;--------------------------------------------------------------------------
; Module constructor/destructor

initcputc:
	lda	#$C0
        .byte   $2C
donecputc:
        lda     #$00
	sta	SCROLL
        rts