Date: Mon, 7 Jun 2004 01:40:12 GMT From: "Steven G. Kargl" <kargl@troutmask.apl.washington.edu> To: freebsd-standards@FreeBSD.org Subject: Re: standards/59797: Implement C99's round[f]() math fucntions Message-ID: <200406070140.i571eC4P006306@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
The following reply was made to PR standards/59797; it has been noted by GNATS. From: "Steven G. Kargl" <kargl@troutmask.apl.washington.edu> To: David Schultz <das@FreeBSD.ORG> Cc: FreeBSD-gnats-submit@FreeBSD.ORG, freebsd-standards@FreeBSD.ORG Subject: Re: standards/59797: Implement C99's round[f]() math fucntions Date: Sun, 6 Jun 2004 18:33:53 -0700 (PDT) David Schultz wrote: > > BTW, benchmarking shows that using the sample implementation that > appears in the C99 standard results in a slowdown of two orders of > magnitude over your round() implementation and four orders of > magnitude over the x87 frndint instruction. Just setting the > rounding mode and calling rint() also results in a significant > slowdown. Thus, we definitely want something that's in the spirit > of what you wrote, but perhaps one that operates on the bits directly. > 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()]. -- Steve http://troutmask.apl.washington.edu/~kargl/
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200406070140.i571eC4P006306>