68 lines
696 B
ArmAsm
68 lines
696 B
ArmAsm
;
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; vbl.s
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; a2bejwld
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;
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; Created by Jeremy Rand on 2016-07-22.
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; Copyright © 2016 Jeremy Rand. All rights reserved.
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;
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.export _vblWait, _vblWait2c, _vblInit2gs
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.export _vblIRQCallback
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.include "apple2.inc"
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RDVBLBAR := $C019
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.proc _vblInit2gs
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lda #$fe
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sta compType
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.endproc
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.proc _vblWait
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lda compType
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@L1:
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cmp RDVBLBAR
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bpl @L1
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@L2:
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cmp RDVBLBAR
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bmi @L2
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rts
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.endproc
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.proc _vblIRQCallback
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pha
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lda #0
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sta vbl2cByte
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pla
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rts
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.endproc
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.proc _vblWait2c
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lda #$ff
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sta vbl2cByte
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@L1:
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lda vbl2cByte
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bne @L1
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rts
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.endproc
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.data
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compType:
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.BYTE $7e
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vbl2cByte:
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.BYTE $00
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