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Fix writing one byte beyond screen buffer.

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This commit is contained in:
Christian Groessler 2013-06-21 01:53:13 +02:00
parent 93bd9a8e51
commit e3fb1b3d3d
1 changed files with 6 additions and 6 deletions
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12
libsrc/atari/clrscr.s
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@ -9,26 +9,26 @@
.importzp ptr1 .importzp ptr1
.import setcursor .import setcursor
SCRSIZE = 960 ; 40x24: size of default atari screen
_clrscr:lda SAVMSC ; screen memory _clrscr:lda SAVMSC ; screen memory
sta ptr1 sta ptr1
lda SAVMSC+1 lda SAVMSC+1
clc clc
adc #>(40*24) adc #>(SCRSIZE-1)
sta ptr1+1 sta ptr1+1
lda #0 ; screen code of space char lda #0 ; screen code of space char
sta OLDCHR sta OLDCHR
ldy #<(40*24) ; 40x24: size of default atari screen ldy #<(SCRSIZE-1)
ldx #>(40*24) ldx #>(SCRSIZE-1)
_clr1: sta (ptr1),y _clr1: sta (ptr1),y
dey dey
bne _clr1 bne _clr1
sta (ptr1),y sta (ptr1),y
dex dex
bmi done bmi done
ldy ptr1+1 dec ptr1+1
dey dey
sty ptr1+1
ldy #255
jmp _clr1 jmp _clr1
done: sta COLCRS done: sta COLCRS