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