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RFC Power PC G3 optimized sqrtf function.
- From: "Conn Clark" <clark at esteem dot com>
- To: libc-alpha at sourceware dot org
- Date: Thu, 14 Dec 2006 11:05:57 -0800
- Subject: RFC Power PC G3 optimized sqrtf function.
Hi everybody,
This is my 1st post and attempt at contributing to glibc
I have written a sqrtf function that is much faster on a PowerPC G3 than
the original one used. It uses the frsqrte instruction and Newton
Goldschmidt iterations to get a result. I have had testing done on G3 and G4
processors and it has results that conform to ieee . Testing on G5's has
shown it gets within at least 2 bits of the correct answer. This shouldn't
matter because the G5 has a hardware sqrtf instruction. It may work on 603,
603e, 604, and 604e processors as well but I have not tested on them. It
will not work on a 601 processor.
The limiting factor on ieee conformance is the frsqrte instruction must
produce a result that is within 1/59th of the correct value. A timing test
on all valid values using the current glibc function takes about 26 minutes
on a iMac g3 400MHz machine. With my implementation it takes about 21
minutes.
Please read the header for more details and give me some feedback.
P.S. Do I need to file copyright assignment papers for this?
Thanks,
Conn
---------------------------------------
Conn Clark
Electronic Systems Technology
415 N. Quay Street Building B1 (509)-735-9092 ext 117
Kennewick, WA. 99336
Gentoo Linux RU13$!!!
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