From: dsp.study on
Hi,

I have successfully converted add, sub, mul and div operations to fixed pt
and see ~10 times improvement.

I'm not sure how to go about doing pow and log functions...can some one
please suggest an algo or pt me to an open source code for reference.

thanks,
Marty


From: glen herrmannsfeldt on
dsp.study <learner.study(a)n_o_s_p_a_m.gmail.com> wrote:

> I have successfully converted add, sub, mul and div operations to fixed pt
> and see ~10 times improvement.

> I'm not sure how to go about doing pow and log functions...can some one
> please suggest an algo or pt me to an open source code for reference.

Fixed point exp() and log() are in Knuth's "Metafont: The Program."

(In Pascal, if that isn't too bad.)

-- glen
From: Greg Berchin on
On Tue, 20 Jul 2010 06:15:44 -0500, "dsp.study"
<learner.study(a)n_o_s_p_a_m.gmail.com> wrote:

>I'm not sure how to go about doing pow and log functions...can some one
>please suggest an algo or pt me to an open source code for reference.

http://groups.google.com/group/comp.dsp/browse_thread/thread/ce4f56d93425ee17
From: robert bristow-johnson on
On Jul 20, 7:15 am, "dsp.study" <learner.study(a)n_o_s_p_a_m.gmail.com>
wrote:
>
> I have successfully converted add, sub, mul and div operations to fixed pt
> and see ~10 times improvement.

on what platform did you do this? the only kind of platform i can
think of that would have this kind of speed improvement is a chip
without native floating-point capability.

and what did you convert the add and sub operations from?

i'm curious.

> I'm not sure how to go about doing pow and log functions...can some one
> please suggest an algo or pt me to an open source code for reference.

do you need bit-wise accuracy? or can you trade off some error
performance for speed performance? for DSP chips, i've always been a
proponent of simple polynomials with optimized coefficients for a
single octave and then to use shift operations to get the other
octaves.

r b-j
From: Tim Wescott on
On 07/20/2010 04:15 AM, dsp.study wrote:
> Hi,
>
> I have successfully converted add, sub, mul and div operations to fixed pt
> and see ~10 times improvement.

In what? Speed? Code size? Weight? Beauty? Management approval? Wages?

> I'm not sure how to go about doing pow and log functions...can some one
> please suggest an algo or pt me to an open source code for reference.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html