From: Jamie Lokier <lk@tantalophile.demon.co.uk>
To: Mike Harrold <mharrold@cas.org>
Cc: Jakob Østergaard <jakob@unthought.net>,
antirez <antirez@invece.org>, Brian Gerst <bgerst@didntduck.org>,
linux-kernel@vger.kernel.org
Subject: Re: * 4 converted to << 2 for networking code
Date: Wed, 10 Jan 2001 17:23:33 +0100 [thread overview]
Message-ID: <20010110172333.J30055@pcep-jamie.cern.ch> (raw)
In-Reply-To: <20010110161146.A3252@unthought.net> <200101101518.KAA11519@mah21awu.cas.org>
In-Reply-To: <200101101518.KAA11519@mah21awu.cas.org>; from mharrold@cas.org on Wed, Jan 10, 2001 at 10:18:38AM -0500
Mike Harrold wrote:
> Be careful. *4 is not a simple <<2 substitution (by the compiler) if
> the variable is signed. *4 translates to 3 instructions (on x86) if
> it's an int.
I think you mean /4 is not the same as >>2 if the variable is signed.
In general, non-widening multiplies give the same result for signed and
unsigned variables.
-- Jamie
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next prev parent reply other threads:[~2001-01-10 16:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-10 16:48 antirez
2001-01-10 14:38 ` David S. Miller
2001-01-10 14:54 ` Brian Gerst
2001-01-10 17:03 ` antirez
2001-01-10 15:11 ` Jakob Østergaard
2001-01-10 15:18 ` Mike Harrold
2001-01-10 15:31 ` Chris Jones
2001-01-10 16:23 ` Jamie Lokier [this message]
2001-01-10 16:26 ` Mike Harrold
2001-01-10 17:25 ` antirez
2001-01-10 16:25 ` Pauline Middelink
2001-01-11 0:29 ` H. Peter Anvin
2001-01-10 22:21 ` Matthias Andree
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