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cc65/libsrc/cbm510/clrscr.s
cuz e1a9115fd4 More P500 support
git-svn-id: svn://svn.cc65.org/cc65/trunk@920 b7a2c559-68d2-44c3-8de9-860c34a00d81
2001-09-14 14:37:08 +00:00

44 lines
651 B
ArmAsm

;
; Ullrich von Bassewitz, 14.09.2001
;
.export _clrscr
.import plot
.include "zeropage.inc"
.include "io.inc"
; ------------------------------------------------------------------------
; void __fastcall__ clrscr (void);
.proc _clrscr
lda #0
sta CURS_X
sta CURS_Y
jsr plot ; Set cursor to top left corner
lda #$20 ; Screencode for blank
ldx #$00
ldy #$00
jsr clearpage
jsr clearpage
jsr clearpage
ldx #<(40*25)
jsr clearpage ; Clear remainder of last page
jmp plot ; Set screen pointer again
.endproc
.proc clearpage
@L1: sta (SCREEN_PTR),y
iny
dex
bne @L1
inc SCREEN_PTR+1
rts
.endproc