07 August 2024, 17:51 | #1 |
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OS3.x - Open a screen with 1x bandwidth
Again something special.
Is there a smart way to open a screen on OS3.x with the 1x bandwidth? The only solution I know is poking in the graphics base like this: Code:
move.l _GraphicsBase,a6 move.b #BANDWIDTH_1X,gb_MemType(a6) Not very system friendly. I did some investigations in the autodocs, but did not find a way to change the bandwidth, after the screen is opened or before with a special tag. Looking in the vieport/viewport extra structure didn't help. Last edited by dissident; 07 August 2024 at 18:00. |
09 August 2024, 07:23 | #2 |
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Do you have any hints for me, Thomas Richter?
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09 August 2024, 20:25 | #3 |
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10 August 2024, 08:44 | #4 |
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Maybe create your own screen bitmap with manually allocated planes that are misaligned (address multiple of 2, but not 4 or 8) such that only 1x is possible. And then open screen with custom bitmap (SA_Bitmap tag).
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10 August 2024, 14:31 | #5 |
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Not a bad idea. I guess I have to explain what should be the purpose of this screen. It‘s part of a display downgrader to get BPL1MOD / BPL2MOD to 0 values. I doubt that the system is smart enough to detect misaligned bitmaps. There must be a reason for the global entry in the graphics base for the bandwidth.
Last edited by dissident; 10 August 2024 at 22:09. |
Yesterday, 00:14 | #6 |
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Not really, but I was busy with PCI workings and finish a driver for PCI-based S3 graphics cards...
No, the FMode is nothing the Os allows you to set or play with. Your best option is probably BestModeID() of graphics to request modes with certain properties. However, what exactly is the application here? |
Yesterday, 07:49 | #7 | ||
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Quote:
Quote:
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Yesterday, 09:52 | #8 |
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Actually, graphics goes through multiple functions for computing what the best possible FMode could be, not only depending on alignment but also on the number of reserved sprites and adapts to the requirements. But the algorithm is opaque and undocumented.
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Today, 02:26 | #9 | ||
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Quote:
Quote:
So I better keep my hands off the gfx base and initialize the BPLMOD registers manually after LoadView(Null) |
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