Date: Sun, 12 Aug 2012 22:56:06 -0000 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Peter Jeremy <peter@rulingia.com> Cc: Diane Bruce <db@db.net>, John Baldwin <jhb@freebsd.org>, David Chisnall <theraven@freebsd.org>, Stephen Montgomery-Smith <stephen@missouri.edu>, Bruce Evans <bde@freebsd.org>, Bruce Evans <brde@optusnet.com.au>, David Schultz <das@freebsd.org>, Warner Losh <imp@bsdimp.com> Subject: Re: Use of C99 extra long double math functions after r236148 Message-ID: <20120717043848.GB87001@troutmask.apl.washington.edu> Resent-Message-ID: <20120812225559.GF20453@server.rulingia.com> In-Reply-To: <20120717042125.GF66913@server.rulingia.com> References: <201207130818.38535.jhb@freebsd.org> <9EB2DA4F-19D7-4BA5-8811-D9451CB1D907@theravensnest.org> <C527B388-3537-406F-BA6D-2FA45B9EAA3B@FreeBSD.org> <20120713155805.GC81965@zim.MIT.EDU> <20120714120432.GA70706@server.rulingia.com> <20120717084457.U3890@besplex.bde.org> <5004A5C7.1040405@missouri.edu> <5004DEA9.1050001@missouri.edu> <20120717040118.GA86840@troutmask.apl.washington.edu> <20120717042125.GF66913@server.rulingia.com>
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On Tue, Jul 17, 2012 at 02:21:25PM +1000, Peter Jeremy wrote: > On 2012-Jul-16 21:01:18 -0700, Steve Kargl <sgk@troutmask.apl.washington.edu> wrote: > >On Mon, Jul 16, 2012 at 10:40:25PM -0500, Stephen Montgomery-Smith wrote: > >> > >> I came up with pseudo code that looks a bit like this. > ... > >Stop. Please see msun/src/math_private.h. You cannot > >use I in any expression. > > Note the "pseudo code" reference. I agree that the actual code has to > jump through hoops to avoid compiler issues with complex arithmetic > but doing that for pseudocode just obfuscates it. > > >Also, consult n1256.pdf for x,y = +-0, +-inf, nan. > >There are specific requirements that must be met. > > Again, handling the special cases listed in G.6 is all just > boilerplate code that we can take as assumed for pseudocode. IMO, it > would be nice if we could come up with a formal, compact (one/line per > rule) representation of G.6 that could be pre-processed into wrapper > code that handles all the 0/Inf/NaN special-cases and then calls > FOO_finite() which has the hand-written code to handle "normal" cases. > As someone who spent 10+ years getting sqrtl(), cbrtl(), ccosh(), sinl(), cosl(), tanl(), etc into FreeBSD, I respectfully disagree with your take that it is just boilerplate. Getting this stuff right is much harder than I think some people understand. Oh well, I'll back to lurking and working on things I need. -- Steve
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