Fixed point matrix representation considered harmful

Simon Thum simon.thum at
Thu Mar 20 14:41:56 PDT 2008

Joerg Sonnenberger wrote:
>>> Except that it complicates decoding for non-IEEE platforms. Think VAX.
>> Are we actually designing for VAX these days? There aren't many other
>> non-IEEE platforms that I know of: even lame embedded/consumer chips are
>> pretty much all IEEE now, TTBOMK.
> Well, at least some of the RISC platforms have IEEE-like floating point,
> but don't do the magic values. Think about Alpha. My point is to just
> specify a simple binary format and leave out all the special magic
> values.
You'll have to do sanity checks independent of the platform. It's 
actually quite hard to avoid special values by (re)specifying the binary 
representation. How to make denorms unrepresentable?

IMHO: Much pain, no gain.

That leads me to the question if threre is any policy or precedence on 
float-over-wire? I could really use it if it was officially blessed. A 
quick grep gives me glxproto.h and some floats in 
xf86vidmodeproto/xf86vmode.h. Is there any 'official' policy on this?



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