Re: [linux-audio-dev] Another Annoying "How Do I Get Started" Question

[Greg Berchin]

Steve Harris wrote:

>I don't understand the hardware issues, but as the filter coefficent 
>appraoches 0.0f the number of cycles taken to multiply it goes up 

This confuses me.  In reading the documentation for the FPU on the Athlon,
they state that it can perform two pipelined double precision floating
point multiplies per cycle.  They do not mention any changes in this
performance that is dependent upon the values of the numbers to be
multiplied.

>I've never programmed for a DSP chip but looking at the implementations 
>of people who do they must be getting much greater guaranteed 
>performance out of modern DSP chips than you can out of a PIII for 
>exmaple. 

There were some benchmarks in a recent issue of EE Times magazine, I think,
in which the GHz Pentium III blew the doors off just about every available
DSP for FFT computations and other real-world numerical tasks.  The only
places where DSPs have real advantages any more are low-cost and low power
applications.

>(don't DSP chips use extgernal GP chips to do that sort of thing?).

Depends upon the application and the design.  In the products that I have
worked on, the DSPs were used strictly for DSP.  Ancillary functions, such
as coefficient calculation, were relegated to a general purpose processor. 
It doesn't HAVE to be that way, though.

Greg Berchin