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Set cursor in top left corner in clrscr()

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as documented in conio.h
This commit is contained in:
Stephan Mühlstrasser 2014-11-29 20:50:48 +01:00
parent ac88639f4a
commit 6dc8621fa5
1 changed files with 16 additions and 10 deletions
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26
libsrc/c1p/clrscr.s
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@ -2,6 +2,8 @@
; void clrscr (void);
;
.export _clrscr
.import plot
.importzp CURS_X, CURS_Y
.include "c1p.inc"
; Adapted from the Challenger Character Graphics
@ -10,16 +12,20 @@
BANKS = VIDEORAMSIZE / $100
_clrscr:
lda #$20 ;' '
ldy #BANKS
ldx #$00
lda #$20 ;' '
ldy #BANKS
ldx #$00
staloc:
sta SCRNBASE,X
sta SCRNBASE,X
inx
bne staloc
inc staloc+2
bne staloc
inc staloc+2
dey
bne staloc
lda #>(SCRNBASE) ; load high byte
sta staloc+2 ; restore base address
rts
bne staloc
lda #>(SCRNBASE); load high byte
sta staloc+2 ; restore base address
lda #$00 ; cursor in upper left corner
sta CURS_X
sta CURS_Y
jmp plot ; Set the cursor position