Date: Tue, 11 Feb 2003 06:25:21 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Mike Barcroft <mike@FreeBSD.ORG> Cc: standards@FreeBSD.ORG Subject: Re: signbit() implementation question Message-ID: <20030211055050.Q2485-100000@gamplex.bde.org> In-Reply-To: <20030210123510.B40864@espresso.q9media.com>
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On Mon, 10 Feb 2003, Mike Barcroft wrote: > I'm wondering if any casts from float->double or long double->double > will cause the sign-bit to change. In my implementation I just have > the macro pass its argument to a function that takes a double for its > argument. In the tests I've done the sign-bit never changes with > these casts, but I don't know if this is guaranteed to work for all > values or whether this is completely portable. Preserving the sign bit in conversions and rounding, etc. is required by at least ieee854 (section 6.3), so I think all reasonable hardware preserves it. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-standards" in the body of the message
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