> list some of the advantages of using dsp processor over risc processor
> for applications like mpe4 encoder.
>
List homework topic. Kthxbye pls.
pete
--
pete@fenelon.com "how many clever men have called the sun a fool?"
Reply by Tim Wescott●July 19, 20072007-07-19
swami wrote:
> list some of the advantages of using dsp processor over risc processor
> for applications like mpe4 encoder.
>
> what i feel is dsp processor executes more instructions in a single
> clockcycle.
> but this consumes more processing power.
>
> can some body put much more strong reason for it.
>
DSP processors are optimized for implementing algorithms that feature a
mix of "regular algorithmic stuff" plus a large number of highly
repetitive tasks, like vector dot products (a FIR filter implementation
is essentially a vector dot product). All of the DSP chips in current
production that I know of will do a vector dot product in one clock
cycle per element in the vector; they scream at this.
As a consequence of this focus on vector dot products and other highly
repetitive tasks, DSP processors are less able to do other things really
well. Specifically, the ones that I have worked with have required
large context switches to maintain the vector dot product state machine,
or they will not execute an interrupt while they're performing a vector
dot product, or they store their vector dot product state machine in
registers that are inaccessible to to use code, which makes any kind of
a normal 'RTOS-like' context switch impossible.
RISC processors are optimized for implementing just about any algorithm
that comes down the pike, without emphasis on any one thing.
Consequently, they don't scream through vector dot products the way a
DSP chip will, but they are at least as good, or better, at performing
other operations, and they don't have the nasty context switching
difficulties that DSP chips do, so an RTOS is more efficient to
implement (if you feel you need one).
I'm not sure how this applies to the efficiency of an MPEG4 encoder,
particularly since there are a lot of different ways you can encode
MPEG. It really boils down to whether you are doing the kinds of things
that a DSP chip is good for -- if you are, it will be to your advantage
to use one. If you're doing a lot of function calls, memory searches,
indexing, and other related stuff, and not a lot of vector dot products,
then a RISC chip will probably be just as good as any DSP, and cost you
less in other ways.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
Reply by swami●July 19, 20072007-07-19
list some of the advantages of using dsp processor over risc processor
for applications like mpe4 encoder.
what i feel is dsp processor executes more instructions in a single
clockcycle.
but this consumes more processing power.
can some body put much more strong reason for it.