GLX available?

M. Edward (Ed) Borasky znmeb at cesmail.net
Mon Jan 7 09:06:53 EST 2008


NoiseEHC wrote:
> Try to contact him, he ported TinyGL successfully:
> http://lists.laptop.org/pipermail/devel/2007-June/005375.html
> 
> 
> 
>> As a data point, Doom runs quite fast even at full resolution on a  
>> B4. Have not heard reports on getting Quake running. But I suspect  
>> that a software renderer hand-optimized towards the XO could be made  
>> to work at decent frame rate.
>>
>>   
> The databook of the LX is so low quality that hand optimization requires 
> testing everything (including if the published clock counts are matching 
> reality) and it has not been done yet. Also the hight cache hit penalty 
> and the in-order nature of the Geode means that a different algorithm 
> could be required than naively fetching texels while texture mapping. 
> Quake requires a preprocessed/prelit BSP tree so unless you want to 
> write an FPS it is not a perfect fit. Preprocessing also could take 
> hours on an XO (if you want children to design levels).
> 
> Just a quick calculation (400x300, 30 fps):
> 400x300x30 = 3 600 000 pixels/sec filled (with no overdraw)
> 433 000 000/3 600 000 = 120 clock/pixel (if you do not do anything else 
> in the code, but just divide it by 4 because of game logic/geometry 
> transform/overdraw)
> So you have ~30 clock/pixel and a cache miss takes 25 clocks (if the 
> documentation is ok but not tested)...
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> 

1. While it does not cover the Geode (or any AMD chips other than
Athlon64), there is a wonderful reference on C/C++ and assembler
tweaking, including some assembly language tools for figuring out what
your chips are up to, at http://www.agner.org/optimize.

2. The Vector Pascal compiler
(http://www.dcs.gla.ac.uk/~wpc/reports/compilers/compilerindex/x25.html)
and the book about it (_SIMD Programming Manual for Linux and Windows_)
have excellent coverage of the MMX and 3dNow! instruction sets. The
compiler and IDE are written in Java, so you probably want to do
cross-compiles/links on a Fedora box.



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