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Digger
Registered: Mar 2005
Posts: 448 |
$d011 trickery duplicated text lines
Does any one know the $d011 trick to repeat the first char row? I am trying to cancel badlines on the 8th line of each charline (between cycles 54-57) but it doesn't work. The first line gets duplicated but only twice. |
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Oswald
Registered: Apr 2002
Posts: 5127 |
Hello :-)
Before I go into trial and error mode I ask: I want to repeat full rows, but I also want badlines, and preferably the least d011 writes possible. it this possible, and how? :)
judging by cruzer's post doable, but he seemingly talks about toucing d011 every line. |
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Digger
Registered: Mar 2005
Posts: 448 |
@Oswald: Badline will cause to refetch the next charline, and you want to have a badline without that I presume? Why? :D |
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JackAsser
Registered: Jun 2002
Posts: 2038 |
Quote: Hello :-)
Before I go into trial and error mode I ask: I want to repeat full rows, but I also want badlines, and preferably the least d011 writes possible. it this possible, and how? :)
judging by cruzer's post doable, but he seemingly talks about toucing d011 every line.
Just trigger a badline before RC<7. If RC==7 on a badline you’ll go to the next row. This is just an FPP. You will not be able to have full 8 lines high rows, only 7. |
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Oswald
Registered: Apr 2002
Posts: 5127 |
Quote: Just trigger a badline before RC<7. If RC==7 on a badline you’ll go to the next row. This is just an FPP. You will not be able to have full 8 lines high rows, only 7.
ah ok guess this is the easy to do, you can repeat a char row after having any nr of its lines displayed.
but I really really need full 8 lines. impossible? : ( |
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Oswald
Registered: Apr 2002
Posts: 5127 |
Quote: @Oswald: Badline will cause to refetch the next charline, and you want to have a badline without that I presume? Why? :D
hehe, there is a neat trick (or rather plan) behind it, yes. I'll tell when the part is released :) if only 7 lines rows possible then its pointless I guess. |
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JackAsser
Registered: Jun 2002
Posts: 2038 |
Quote: hehe, there is a neat trick (or rather plan) behind it, yes. I'll tell when the part is released :) if only 7 lines rows possible then its pointless I guess.
If RC=7 then VC->VCBASE regardless of badline condition, so no, only 7 lines. |
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ChristopherJam
Registered: Aug 2004
Posts: 1424 |
Quoting Oswaldif only 7 lines rows possible then its pointless I guess.
Eh, I used a new instance of row 0 every 5 rasters in Jam Ball 2 to keep my framebuffer size down and thought that was reasonably worthwhile :)
Alternately (assuming you can afford to lose another 60 or so cycles) you could do two badlines at the start of every group of eight and use one charset/bitmap for the first line and another for the remaining seven. |
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Oswald
Registered: Apr 2002
Posts: 5127 |
what if I do the "no badline" row repeat on the last pixel row of a char row, but then manually make a badline in the next raster line ? can this be done ?:P |
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ChristopherJam
Registered: Aug 2004
Posts: 1424 |
Sadly not. The issue is that each “no badline” row repeat secretly updates the row pointer to the next row, so the moment you do a DMA you’d get a later row than what you want,
(Useful for other effects of course, like double buffering half res d800) |
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Oswald
Registered: Apr 2002
Posts: 5127 |
what you describe sounds like the normal behaviour ? rc to 0 and next row read up. |
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