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|
;
; Christian Groessler, November-2002
;
; cursor handling, internal function
.include "atari.inc"
.import cursor,_mul40
.export setcursor
.proc setcursor
ldy #0
lda OLDCHR
sta (OLDADR),y
lda ROWCRS
jsr _mul40 ; function leaves with carry clear!
adc SAVMSC ; add start of screen memory
sta OLDADR
txa
adc SAVMSC+1
sta OLDADR+1
lda COLCRS
adc OLDADR
sta OLDADR
bcc nc
inc OLDADR+1
nc: lda (OLDADR),y
sta OLDCHR
ldx cursor ; current cursor setting as requested by the user
beq off
ldx #0
beq cont
off: inx
cont: stx CRSINH ; update system variable
beq turnon
and #$7f ; clear high bit / inverse flag
finish: sta (OLDADR),y ; update on-screen display
rts
turnon: ora #$80 ; set high bit / inverse flag
bne finish
.endproc
|
