🚀 go-pugleaf

In article <943r3l$hn2$1@nnrp1.deja.com>, petrock
<petrock00@my-deja.com> wrote:

> Can I simply enable the Altivec compile settings in my existing code and
> recompile and it will have Altivec optimizations (At least the MacOS
> functions)?  like it kind of was with the 68k to PPC transition...

Metrowerks compiler does not do this. If you check out
<http://www.psrv.com/>, they make a vectorizing compiler for C, and
they say that C++ and Fortran are on the way. I've never used it, so I
don't know how well it works.

> Are there any tutorials or good books on Altivec programming?

You might search the MacHack web site or CDs to see if Doug Clarke's
presentations about AltiVec are there. Everything I know about AltiVec
I learned from Doug. Well, that and by making numerous mistakes on my
own. :-)

You can also get on the AltiVec list at www.altivec.org.

> it seems to me that Altivec code is very close to Assembly.  Assembly
> isn't that easy to code with.  Are their any libraries I can use to do
> alot of the work for me?

It's not that bad, really. You can even do crazy things like:

v1 = vec_add (vec_sub(v1,v2), vec_add (v3,v4));

That's equivalent to

v1 = (v1 - v2) + (v3 + v4);

Personally, I try to keep things to one AltiVec instruction per line.
It helps me optimize later, but there's no reason you have to do it
that way.

As others have said, there are various libraries available. Be careful
of vMathLib, though, as the trig functions are wacked. They are either
very buggy, or I'm using them in some unintended way. For example, the
sin and cos functions will return values outside of the -1 to 1 range.
It's always repeatable, and always the same result, but it's wrong, as
far as I can tell.

Hope that helps,
Darrin

-- 
Darrin Cardani
Buena Software, Inc. - Macintosh Video, Graphics and Audio Contract Development
http://www.buena.com/
dcardani@buena.com