Re: pointer movement?

["DuckE" <nospam_steved94@home.com>]

"John R. Strohm" <strohm@airmail.net> wrote in message
news:0232EB9B71AA469C.63E4D85432274436.A56779B689231DC6@lp.airnews.net...
> I *KNOW* this is a stupid question, but (a) did you look at the generated
> object code (b) keeping in mind the organization of the memory and the
> caching and the response times?

No I did not look at the generated object code.  I found certain techniques
to improve speed by experimenting with the source code.  The MVME162 has an
available timer on board that permits me to time execution to the nearest
nanosecond.  I was able to make minor changes to the source code and observe
changes to execution speed very easily.

> A few years ago, I was doing image processing with a TI 320C80.  The way
one
> walked through the image (row-wise vs. column-wise) made a MAJOR
difference
> in the raw processing speed, because the RAM arrays could access
successive
> locations in a "row" a LOT faster than they could access successive
> locations in a "column".  Some of the processing I was doing naturally
> worked on a row at a time; some naturally worked on a column at a time.
We
> compromised for consistent transfer times by processing small rectangular
> patches at a time.

I was working with single dimension arrays.

> 320C80 image processing code is some of the hardest I have ever done.  You
> sweat blood for months over a loop with maybe twenty or thirty source
> instructions in it, because that loop HAS to touch every pixel in the
frame,
> and the system HAS to run at video speed.  I thank my lucky stars I got my
> start on a CDC 6600 all those years ago; the mindset from 6600 programming
> came in handy.

It's a pity that on occasion we still have to program at this level.

SteveD