mirror of
https://github.com/cc65/cc65.git
synced 2024-12-23 19:29:37 +00:00
48 lines
920 B
ArmAsm
48 lines
920 B
ArmAsm
;
|
|
; Ullrich von Bassewitz, 2003-04-13
|
|
;
|
|
|
|
.export _clrscr
|
|
.importzp ptr2
|
|
|
|
.include "atmos.inc"
|
|
|
|
; ------------------------------------------------------------------------
|
|
; void __fastcall__ clrscr (void);
|
|
|
|
.proc _clrscr
|
|
|
|
; Set the cursor to top left cursor position
|
|
|
|
ldy #$00
|
|
sty CURS_X
|
|
sty CURS_Y
|
|
|
|
; Set ptr2 to the screen position (left upper border)
|
|
|
|
lda #<SCREEN
|
|
sta ptr2
|
|
lda #>SCREEN
|
|
sta ptr2+1
|
|
|
|
; Clear full pages. Y is still zero
|
|
|
|
ldx #>(28*40)
|
|
lda #' '
|
|
@L1: sta (ptr2),y
|
|
iny ; Bump low byte of address
|
|
bne @L1
|
|
inc ptr2+1 ; Bump high byte of address
|
|
dex
|
|
bne @L1
|
|
|
|
; Clear the remaining page
|
|
|
|
@L2: sta (ptr2),y
|
|
iny
|
|
cpy #<(28*40)
|
|
bne @L2
|
|
rts
|
|
|
|
.endproc
|