Re: [Xylo-SDR] Firewire, DSP and FPGA on one module

[Ramakrishnan Muthukrishnan <vu3rdd@gmail.com>]

Yes, Bob. It is too difficult to write assembly code which makes use
of all the eight functional units of the C6x architecture, though it
can be done and we do it many a times. But with proper pragmas, C code
can be written which are probably 10-20% close in cycles to hand
optimized assembler code.

I understand that afew students at a  German University is doing a gcc
port. With the new tree-ssa optimizations available in the gcc, it
could probably be possible to use the software pipelining optimizer in
gcc. I do not fully understand how this works, but looks like people
have used this new feature in gcc to actually write optimizing
compilers for other VLIW architectures like the Itanium. Since I do
not run Windows at home (for the past eight years or so), I am waiting
for the day when free tools are available for DSPs. It's not that I am
going to modify the sources, but the fact that there is a community
behind it to fix the problems is a great thing, like the way
SDR1k/powerSDR project works.

73
Ramakrishnan

On 12/19/05, Robert McGwier <rwmcgwier@comcast.net> wrote:
> Ramakrishnan:
>
>
> The 67XX is the very first DSP chip where I believed it was actually
> necessary to use a development system rather than writing assembler.
> The very long instruction word,  sometimes executing 16 instructions in
> parallel (!!!!!) makes it almost a requirement to use computer aided
> optimization tools to reorder instructions. It is understandable why
> these tools are not free.  I also think that nearly four thousand
> dollars a seat is absolutely outrageous.  Thank goodness I get an
> educational discount.  I played these games by hand when I was
> programming the DSP56001 (which also had multiple functional units
> running in parallel) but it was manageable.    The other thing I like
> about it is that it also does fixed point natively and it really
> blisters in those modes.  For truly high speed operation, it is critical
> to use optimized libraries for the "big things".
>
>
> Bob
>
>
>
>
> Ramakrishnan Muthukrishnan wrote:
>
> >Bob,
> >
> >another big problem with using C-incapable DSP chips is the fact that
> >once these are obsolete, it needs to be ported to the new processor.
> >C67x is a nice part. I use C64x in my day job and have used all the
> >other 16-bit fixed point TI parts too (I work for TI). If there were
> >free tools, I would have definitely prefered to use a C67xx part for
> >PIC-A-STAR, which would have given me more MIPS to do more interesting
> >stuff and also write everything with C.
> >
> >Ramakrishnan
> >
> >
> >
>
>
> --
> Laziness is the number one inspiration for ingenuity.  Guilty as charged!
>
> _______________________________________________
> Xylo-SDR mailing list
> To post msg: Xylo-SDR@ae5k.us
> Subscription help: http://lists.ae5k.us/listinfo.cgi/xylo-sdr-ae5k.us
> Xylo-SDR web page: http://xylo-sdr.ae5k.us
> Forum pages: http://www.hamsdr.com/hamsdrforum/
>


--
   73, Ramakrishnan - VU3RDD