Lpc2000

On Monday 16 May 2005 12:25, James Dabbs wrote:
> Crap.  This message obviously makes no sense.  Please replace "JTAG"
> with "JPEG".  I am looking for a faster JPEG decoder for ARM.

I hate it when I do that too :-).


> > I'm looking for an optimized JTAG decoder built for
> > fixed-point ARM7. Is there such a thing, and where do I go
> > look?  Or, is there a compression standard other that JPEG
> > that gives similar compression with less CPU bandwidth from a
> > fixed-point CPU like ARM?

would think that you first need to evaluate the relative cost of a 
development vs extra hardware. 

If you feel that it is worth doing a special version of code to use cheaper 
CPUs, then I'd take the following approach:
0) If you are not very ARM-savvy, and have a budget, get someone else with 
ARM expertise to do it. eg. say www.bluewatersys.com whom I would recommend 
to anybody. 
- otherwise -
1) Write as much as you can in C. You can help your code run fast by 
following the ARM-friendliness guidelines mentioned a few times before. eg. 
Use U32 variables instead of U8 etc. Look at 
http://www.arm.com/pdfs/DAI0034A_efficient_c.pdf
2) Profile. You'll likely find that a small % of the code contributes a lot 
of overhead. Put effort into optimising that. Get clever using nifty ARM 
features etc.

In general you get better payback by highly optimising 5-10% of the code than 
doing a half-job on all the code.

-- CHarles