Date: Tue, 16 Nov 1999 09:45:36 +0100 From: Pierre Beyssac <beyssac@enst.fr> To: Bruce Evans <bde@zeta.org.au> Cc: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, Sheldon Hearn <sheldonh@uunet.co.za>, freebsd-current@FreeBSD.ORG Subject: Re: egcs -O breaks ping.c:in_cksum() Message-ID: <19991116094536.A44999@enst.fr> In-Reply-To: <Pine.BSF.4.10.9911161448210.780-100000@alphplex.bde.org>; from Bruce Evans on Tue, Nov 16, 1999 at 03:17:43PM %2B1100 References: <19991115194357.T28348@enst.fr> <Pine.BSF.4.10.9911161448210.780-100000@alphplex.bde.org>
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On Tue, Nov 16, 1999 at 03:17:43PM +1100, Bruce Evans wrote:
> On Mon, 15 Nov 1999, Pierre Beyssac wrote:
> > - volatile u_short answer = 0;
> > + union {
> > + u_int16_t us;
> > + u_int8_t uc[2];
> > + } answer;
>
> This has indentation bugs.
Uh, which one(s) do you mean exactly? The 4-space indented union
(I just followed style(9)) or the double space before uc[2] (it
was just to align us and uc vertically)?
> ping.c still assumes that u_short is u_int16_t everywhere else.
But in_cksum() is more or less self-contained. Probably it's more
consistent (even withing in_cksum which uses u_short elsewhere) to
change back the union to u_short and u_char, though.
> This `answer' variable has nothing to do with the final `answer' variable.
> The latter should not be a union. The original code apparently reuses
> `answer' to do manual register allocation for ancient compilers.
Agreed.
> Perhaps the above should be written as:
>
> sum += ntohs(*(u_char *)w << 8);
>
> to avoid the undefined union access (answer.us).
Uh... I'm not sure I don't prefer the union, actually :-)
--
Pierre Beyssac pb@enst.fr
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