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From: | Leonardo E. Reiter |
Subject: | Re: [Qemu-devel] Updated BGR vs. RGB vga patch... |
Date: | Mon, 10 Apr 2006 12:41:31 -0400 |
User-agent: | Mozilla Thunderbird 1.0.7 (X11/20051013) |
As for where to add it, I agree that the low level conversions are not a great place to add this. I didn't originate the patch, I just updated it. Unfortunately none of the VGA is optimized - everything happens pixel by pixel already. Adding what probably amounts to 2 instructions (probably a couple of clock cycles) per pixel doesn't seem to do anything for performance really. The VGA is already slow.
Unfortunately X11 will not allow you to force a certain color order in 24-bit mode. You can tell it to force byte-order but this only affects 16-bit blits - it's ignored for 24-bit since the individual components of the 24-bit blits, even if packed into 32-bits, are still 8-bits long. That's what the color masks are for. There is no efficient way to do this at the server level that I can see. If you find a better way (within the current scope of the VGA architecture), I'd be glad to try to implement it. I was just sharing something that was useful to me.
Thanks, Leo Reiter Paul Brook wrote:
On Monday 10 April 2006 17:25, Leonardo E. Reiter wrote:Hello, attached is an updated version (against today's CVS) of a patch to enable B/G/R color encoding rather than R/G/B with the command-line option -bgr. I found the original here (post by Martin Bochnig):Shouldn't we be able to figure this out by asking SDL and/or the X server?Also, adding an if to the low-level conversion routines seems a bad idea for performance.Paul
-- Leonardo E. Reiter Vice President of Product Development, CTO Win4Lin, Inc. Virtual Computing from Desktop to Data Center Main: +1 512 339 7979 Fax: +1 512 532 6501 http://www.win4lin.com
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