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44 lines
1.3 KiB
ArmAsm
44 lines
1.3 KiB
ArmAsm
; alternate implementation by Oliver Schmidt
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; from https://github.com/cc65/cc65/blob/master/libsrc/apple2/waitvsync.s
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wait_vblank_iic:
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; sei ; disables interrupts
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sta IOUDISOFF
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lda RDVBLMSK
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bit ENVBL
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bit PTRIG ; Reset VBL interrupt flag
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: bit RDVBLBAR
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bpl :-
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asl
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bcs :+ ; VBL interrupts were already enabled
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bit DISVBL
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: sta IOUDISON ; IIc Tech Ref Man: The firmware normally leaves IOUDIS on.
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; cli ; re-enable interrupts
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rts
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;===========================
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; wait for vblank on IIgs
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; opposte of IIe?
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wait_vblank_iigs:
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lda VBLANK
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bpl wait_vblank_iigs ; wait for negative (in vblank)
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wait_vblank_done_iigs:
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lda VBLANK ; wait for positive (vlank done)
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bmi wait_vblank_done_iigs
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rts
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;===========================
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; wait for vblank on IIe
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wait_vblank_iie:
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lda VBLANK
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bmi wait_vblank_iie ; wait for positive (in vblank)
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wait_vblank_done_iie:
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lda VBLANK ; wait for negative (vlank done)
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bpl wait_vblank_done_iie
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rts
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