[Tremor] tremor on 54x?

[Monty]

On Fri, Jul 02, 2004 at 02:16:02PM -0700, Rocky Lin wrote:
> Hi,
>
> Has anybody been able to get Tremor working on the TI 54x family of DSP's?
> If so, what type of performance to do you see from this codec?

I've done it, but prefer not to work with the 54xx again if I can help
it :-)

The ALU structure is rather ad-hoc, and the development tools
are... not good.  For one thing, the C compiler included in CCs is the
worst optimizer I've ever seen, mainly because TI strongly encourages
coding in assembly for this family.  I stopped maintaining my port at
the point the CCS IDE/debugger would simply crash any time it tried to
look at a recent version of the code.  TI's support response was "Oh,
it just does that; back out any source changes that cause it to
crash."  Unfortunately, that began after a merge so goodness only
knows what the change was...

Aaanyway....

I estimated at the time that decode was taking about 40 MIPS on the
54C16 for -q 4 files; the MIPS usage was heavily dependent on bitrate.
The ALU structure makes variable shift operations very time consuming,
and so the bit unpacker is the bottleneck.

If you have the option of choosing a more flexible DSP family, I'd
encourage it.  ARM is heartily recommended, BTW, if only to guarantee
inexpensive, working development tools.  The processor family itself
is also rather nice (barrel shift on ALU inputs, not as a restricted
opcode!)

Monty