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24 lines
640 B
ArmAsm
24 lines
640 B
ArmAsm
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; 2019-09-16, Greg King
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; unsigned char __fastcall__ revers (unsigned char onoff);
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;
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.export _revers
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.include "cx16.inc"
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.proc _revers
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ldy #$00 ; Assume revers off
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tax ; Test on/off
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beq :+ ; Jump if off
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ldy #$80 ; Load "on" value
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ldx #>$0000 ; Zero high byte of result
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: lda RVS ; Load old value
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sty RVS ; Set new value
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clc
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rol a ; Convert bit-mask into boolean
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rol a
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rts
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.endproc
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