Ian,
Without going into gory details...
Essentially there is a 2-D surface that can be described by a set of
equations. I am searching through a 3-D grid, to find out which grid
points the surface passes though. For each grid-point the surface
passes through, the 'score' associated with the grid point is
incremented.
So in my vectors are indices that need to be incremented. I didn't
mention this before, but the vector->scalar conversion is inside some
if-statements within the do loop, so it is not executed every time
through the loop.
I have not done a lot of profiling (just using -gp and gprof), but the
GetFourFloats function that does the extraction is not listed
anywhere... Perhaps because I have it in-lined. As I said before,
though, the vector version is 2 times faster than the scalar version....
Roger
-----Original Message-----
From: email@hidden
[mailto:email@hidden] On Behalf Of Ian Ollmann
Sent: Friday, April 02, 2004 3:29 PM
To: Apple SciTech
Subject: Re: Altivec: Extracting Floats From Vector Float
Roger,
Go to GREAT lengths not to do this. It is bad, bad, bad and even worse
than that on G5.
What are you really trying to do?
Ian
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