AVR-Chat

On Thu, Feb 09, 2006 at 05:53:56PM -0000, Dave VanHorn wrote:
> 
> > Also spend a lot of time looking at the generated assembly output.
> > Is not so important as to be able to write assembly as it is to be
> > able to read and understand what the compiler thought of your
> > instructions. This way you know how expensive it is to attempt to
> > abstract the UART via indirection in a structure. You know that 16
> > bit values require two accesses which an interrupt may jump in
> > between. All those little things that differentiate code which
> > happens to work vs. solid code which always works and is easy to
> > maintain.
> 
> I know a lot of people use C, and yet I see this sort of thing, and
> compiler bugs, and rather bad code optimization, and I think.. "and 
> this is better?"

I didn't say anything about compiler bugs. My concern was in
understanding how what one writes in C turns into machine instructions.

I know a code generation error crops up now and then in avr-gcc, but
those are rare.

As for optimization, if the code runs correctly then a few extra
instructions here and there do not matter. This time last year avr-gcc
emitted extra RET instructions in some situations. I knew because I was
looking at the output. I didn't fret about my project being 55 RET's
longer than it needed to be.

> > One parting note, use some sort of version system. CVS, Subversion,
> > something, anything, from the start. Get used to frequently updating
> > your repository with concise comments as to what you were doing or
> > what motivated the changes. Comments in the code are important but
> > the quality of comments in your commits are just as important.
> 
> Tortoise CVS makes that pretty painless. I have an offsite CVS server
> which helps protect me from any little disasters.

There are other issues if one uses Windows file sharing to "network" a
CVS repository among Windows users. This is the usual brain-dead method
that comes to mind of many IT staff. Is better to install CVS as a
"service" so that one has true client/server networking, that the server
is the only one to read or write the repository directly. Even better
use FreeBSD as the CVS server.

I agree, TortoiseCVS and WinMerge are essentials if working from
Windows.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.