Carsten Haitzler (The Rasterman)
raster at openmoko.org
Fri Aug 15 07:48:04 CEST 2008
On Thu, 14 Aug 2008 21:54:34 -0700 Russell Sears <sears at cs.berkeley.edu>
> Carsten Haitzler (The Rasterman) wrote:
> > though we need to accept that we need to move beyond SDR into DDR/DDR2 ram
> > and higher clockrates anyway - we need more performance to do the things
> > people want, we just need to do it with the right generation of SOC that
> > has reigned these power requirements in a bit... and well - maybe accept we
> > need a meatier battery :)
> What about an FPU? It probably wouldn't eat much power, and would help
> a *lot* for audio applications, since stuff wouldn't need to be
> rewritten in fixed point arithmetic.
modern arms have fpu's - FR doesn't but the ones i mentioned (omap3xxx and
snapdragon) i am certain have fpu's.
nb. u dont need fp - it's just "lazy programming" to have used floating point
math for the audio - it can be trivially done in integer space. with 16bit
input you can easily do all your work in 32bit scratch-pad registers (no need
for 64bit math). as such this is NOT a reason for an fpu. for 3d geometry and
so on it definitely makes sense though. and with the more modern systems come
graphics units capable of something vaguely decent graphics-wise :) so an fpu
makes sense there. :)
> On a related note (and perhaps on the wrong end of an NDA), any idea
> what the specs are on the glamo's built in openrisc processors?
low to useless. it's slow. also not even under nda is there any info on just
how to program it. it's more of a control cpu - designed for keeping the
internal bits of glamo's silicon in line than actually doing any heavy lifting
of its own.
> Can they do floating point? Randomly access memory? How many of them
> are there?
> If they're beefy enough, with the right drivers (like CUDA), I think
> we'd have the bus bandwidth to offload audio processing (ogg decoding)
> to them, assuming the bus is symmetric:
> 48khz * 16bit/sample * 2channels = 187.5 kilobytes / sec = 1.4 mbit/sec
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Carsten Haitzler (The Rasterman) <raster at openmoko.org>
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