[Speex-dev] SPEEX in a DSPIC - optimisation of iir_mem16() for speed - can it be 16 bit ?

[David Willmore]

On 9/22/07, Simon W Day <swd at phasor-design.uk.com> wrote:
> I would be interested to hear your views on whether SPEEX could be made to
> run fast on a DSPIC33 by the following strategy:

Congratulations with this effort.  I'd like to do that some day, but other
restructions on my time prevent it.

> Make iir_mem16() (for example) purely 16 bit by restricting the number of
> bits in the signal to say 10 using SATURATE and then making the LPC
> co-efficients just 6 bits.
>
> At present (with standard code) the encode function is taking about 140ms
> which is seven times too long !
>
> Any thoughts welcome ? Best wishes for sunny September days. Simon

Simon,  Why are you concerned with limiting things to 16 bit?  The 33F has
a 40bit accumulator in the DSP portion.  Are you trying to use just the MPU
portion of the chip?  If you were porting to the 24F, I could see that--but I
would never recomment trying to run speex on the 24F family. :)

Cheers,
David