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;
; 2003-04-13, Ullrich von Bassewitz
; 2013-07-16, Greg King
;
; void cputcxy (unsigned char x, unsigned char y, char c);
; void cputc (char c);
;
.export _cputcxy, _cputc
.export setscrptr, putchar
.constructor initcputc
.import rvs
.import popax
.importzp ptr2
.include "atmos.inc"
_cputcxy:
pha ; Save C
jsr popax ; Get X and Y
sta CURS_Y ; Store Y
stx CURS_X ; Store X
pla ; Restore C
; Plot a character - also used as internal function
_cputc: cmp #$0D ; CR?
bne L1
lda #0
sta CURS_X ; Carriage return
rts
L1: cmp #$0A ; LF?
bne output
inc CURS_Y ; Newline
rts
; Output the character, then advance the cursor position
output:
jsr putchar
advance:
iny
cpy #SCREEN_XSIZE
bne L3
inc CURS_Y ; new line
ldy #0 ; + cr
L3: sty CURS_X
rts
; ------------------------------------------------------------------------
; Set ptr2 to the screen, load the X offset into Y
.code
.proc setscrptr
ldy CURS_Y ; Get line number into Y
lda ScrTabLo,y ; Get low byte of line address
sta ptr2
lda ScrTabHi,y ; Get high byte of line address
sta ptr2+1
ldy CURS_X ; Get X offset
rts
.endproc
; ------------------------------------------------------------------------
; Write one character to the screen without doing anything else, return X
; position in Y
.code
.proc putchar
ora rvs ; Set revers bit
pha ; And save
jsr setscrptr ; Set ptr2 to the screen
pla ; Restore the character
sta (ptr2),y ; Set char
rts
.endproc
; ------------------------------------------------------------------------
; Screen address table
.rodata
ScrTabLo:
.repeat SCREEN_YSIZE, Line
.byte <(SCREEN + Line * SCREEN_XSIZE)
.endrep
ScrTabHi:
.repeat SCREEN_YSIZE, Line
.byte >(SCREEN + Line * SCREEN_XSIZE)
.endrep
; ------------------------------------------------------------------------
; Switch the cursor off. Code goes into the ONCE segment,
; which will be reused after it is run.
.segment "ONCE"
initcputc:
lsr STATUS
asl STATUS ; Clear bit zero
rts
|
