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Atari demoscene BBS
| Re: R-TYPE DELUXE |
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Posted by: wietze
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Dec,30.2015-09:16
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As I read the documentation, Atari discourages to set the per-pixel finescroll during the vbl, since it causes jumping. As a solution it suggests to set the per-pixel finescroll AFTER the vbl; for example the HBL (but I guess timer a, or timer b is as good as any).
I assume you set the finescroll only once per vbl (or once per frame even?). In this case, the HBL would work to ensure the register is set AFTER the vbl. But if the setting of the register only occurs during the first interrupt of the HBL per vbl, then you may as well raise the interrupt after the first HBL occurs, rather than to load RTE to the HBL interrupt handler.
This would prevent the unnecesarry 300-odd hbl interrupts to occur. So the general approach would be, VBL enables HBL interrupts, HBL interrupt occurs to set address, to subsequently raise interrupt level to prevent additional HBL interrupts to occur during the same VBL.
Again, it may only save you 10% of the total cycles over the average 3 vbls per frame, but its free cycles I believe.
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Topic
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Posted by
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Date
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R-TYPE DELUXE
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Bod/Effect
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Dec,24.2015-11:44
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Re: R-TYPE DELUXE
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s_t_s
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Dec,24.2015-12:38
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Re: R-TYPE DELUXE
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Bod/Effect
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Dec,24.2015-18:54
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Re: R-TYPE DELUXE
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s_t_s
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Dec,24.2015-20:10
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Re: R-TYPE DELUXE
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Bod/Effect
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Dec,24.2015-23:43
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Re: R-TYPE DELUXE
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ggn
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Dec,25.2015-16:15
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Re: R-TYPE DELUXE
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Bod/Effect
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Dec,26.2015-09:03
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Re: R-TYPE DELUXE
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ggn
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Dec,26.2015-09:41
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Re: R-TYPE DELUXE
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Paranoid / pdx
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Dec,26.2015-11:49
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Re: R-TYPE DELUXE
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s_t_s
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Dec,25.2015-16:48
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Re: R-TYPE DELUXE
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bob_er/mec
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Dec,25.2015-16:56
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Re: R-TYPE DELUXE
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Bod/Effect
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Dec,26.2015-09:01
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Re: R-TYPE DELUXE
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Oldskool
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Dec,27.2015-15:24
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Re: R-TYPE DELUXE
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Bod/Effect
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Dec,27.2015-15:52
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Re: R-TYPE DELUXE
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wietze
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Dec,28.2015-02:50
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Re: R-TYPE DELUXE
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Bod/Effect
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Dec,29.2015-19:54
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Re: R-TYPE DELUXE
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wietze
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Dec,30.2015-09:16
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Re: R-TYPE DELUXE
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wietze
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Dec,30.2015-09:23
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What's the anti-troll code?
That's your personal code to be able to add comments and messages on the dhs.nu site.
Don't have a code or forgot it? Fix it here.
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