15 messages in org.freebsd.freebsd-standardsstandards/59797: Implement C99's roun...| From | Sent On | Attachments |
|---|---|---|
| Steven G. Kargl | Dec 9, 2003 8:43 pm | |
| Steven G. Kargl | Dec 9, 2003 8:50 pm | |
| Steven G. Kargl | Dec 10, 2003 9:12 am | |
| Steven G. Kargl | Dec 10, 2003 9:20 am | |
| David Schultz | Jun 4, 2004 7:53 pm | |
| David Schultz | Jun 4, 2004 8:00 pm | |
| David Schultz | Jun 5, 2004 3:49 pm | |
| David Schultz | Jun 5, 2004 3:50 pm | |
| Steven G. Kargl | Jun 7, 2004 1:28 am | |
| Steven G. Kargl | Jun 7, 2004 1:30 am | |
| Steven G. Kargl | Jun 7, 2004 1:33 am | |
| Steven G. Kargl | Jun 7, 2004 1:39 am | |
| David Schultz | Jun 7, 2004 8:11 am | |
| David Schultz | Jun 7, 2004 10:10 pm | |
| David Schultz | Jun 7, 2004 10:20 pm |
| Subject: | standards/59797: Implement C99's round[f]() math fucntions | |
|---|---|---|
| From: | David Schultz (da...@FreeBSD.ORG) | |
| Date: | Jun 7, 2004 10:20:00 pm | |
| List: | org.freebsd.freebsd-standards | |
The following reply was made to PR standards/59797; it has been noted by GNATS.
From: David Schultz <da...@FreeBSD.ORG> To: "Steven G. Kargl" <kar...@troutmask.apl.washington.edu> Cc: Free...@FreeBSD.ORG, free...@FreeBSD.ORG Subject: Re: standards/59797: Implement C99's round[f]() math fucntions Date: Sun, 6 Jun 2004 23:38:43 -0700
On Sun, Jun 06, 2004, Steven G. Kargl wrote:
I would have to go back and review the PR for all the discussion, but I thought bde had proposed using rint(3) with an appropriate rounding mode. Anyway, whatever you decide to do is fine with me.
I found that setting the rounding mode and calling rint(3) is significantly slower on x87, and that's not counting the special handling for the halfway cases. The bit-fiddling approach is a little bit faster than yours (I compared against ceil()), but it's much harder to maintain. Consider that rintf() still has bugs, and it has been around for over a decade!
I looked at the glibc implementation of round(). It does bit twiddling, but I would definitely recommend not using the glibc version because of licensing and possible copyright infringement concerns [hiint compare glibc's round() with fdlibm's ceil()].
Hmmm...the glibc implementation does indeed appear to be plagiarized. Perhaps someone should let the glibc folks know.