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cc65/libsrc/atari/setcursor.s
Christian Groessler a084ea8e42 Atari: split "setcursor" function out of cgetc.s source file into setcursor.s.
This function is used by many other CONIO functions, and the user program not
necessarily uses 'cgetc'. Having "setcursor" in a different object file saves
space in this case and also allows the user program to override it (e.g. when
not using GRAPHICS 0 mode).
2017-10-03 21:58:52 +02:00

49 lines
1.1 KiB
ArmAsm

;
; 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
clc
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