From owner-freebsd-standards  Mon Feb 10  9:47:18 2003
Delivered-To: freebsd-standards@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 9DE1F37B401
	for <standards@FreeBSD.org>; Mon, 10 Feb 2003 09:47:17 -0800 (PST)
Received: from espresso.q9media.com (espresso.q9media.com [65.39.129.122])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 290EE43FB1
	for <standards@FreeBSD.org>; Mon, 10 Feb 2003 09:47:17 -0800 (PST)
	(envelope-from mike@espresso.q9media.com)
Received: by espresso.q9media.com (Postfix, from userid 1002)
	id 604F29C4A; Mon, 10 Feb 2003 12:35:10 -0500 (EST)
Date: Mon, 10 Feb 2003 12:35:10 -0500
From: Mike Barcroft <mike@FreeBSD.org>
To: standards@FreeBSD.org
Cc: Bruce Evans <bde@zeta.org.au>
Subject: signbit() implementation question
Message-ID: <20030210123510.B40864@espresso.q9media.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Organization: The FreeBSD Project
Sender: owner-freebsd-standards@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-standards.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-standards>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-standards>
X-Loop: FreeBSD.ORG


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.

Best regards,
Mike Barcroft

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-standards" in the body of the message