From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-return-92663-listarch-gcc=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 32711 invoked by alias); 15 Mar 2004 22:02:33 -0000
Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <http://gcc.gnu.org/ml/>
Sender: gcc-owner@gcc.gnu.org
Received: (qmail 32704 invoked from network); 15 Mar 2004 22:02:32 -0000
Received: from unknown (HELO punt.aladdin.de) (195.124.73.2)
  by sources.redhat.com with SMTP; 15 Mar 2004 22:02:32 -0000
Received: by punt.aladdin.de; id XAA09642; Mon, 15 Mar 2004 23:05:04 +0100
Received: from caligula.groessler.org(10.23.1.2) by punt.aladdin.de via smap (3.2)
	id xma009640; Mon, 15 Mar 04 23:04:34 +0100
Received: from langhals (langhals.groessler.org [10.23.1.27])
	by Caligula.groessler.org (8.12.10/8.12.9) with ESMTP id i2FM1ck1000831;
	Mon, 15 Mar 2004 23:01:38 +0100 (CET)
	(envelope-from cpg@aladdin.de)
Received: from langhals ([127.0.0.1] helo=langhals.aladdin.de)
	by langhals with esmtp (Exim 3.36 #1 (Debian))
	id 1B309z-00015o-00; Mon, 15 Mar 2004 23:02:11 +0100
To: Ian Lance Taylor <ian@wasabisystems.com>
Cc: GCC List <gcc@gcc.gnu.org>
Subject: Re: signed/unsigned right shift
From: Christian Groessler <cpg@aladdin.de>
Date: Mon, 15 Mar 2004 22:02:00 -0000
Message-ID: <87ish53h24.fsf@aladdin.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-SW-Source: 2004-03/txt/msg00744.txt.bz2

On 03/14/2004 01:23:18 PM EST Ian Lance Taylor wrote:
>
>Christian Groessler <cpg@aladdin.de> writes:
>
>> >Correct, the multiplication is done as signed int.  And it is
>> >implementation
>> >defined whether right shift of a negative signed int does sign fill or
>> >not.
>> >So both compilers are right; it is only your code that's wrong.
>> >
>> >C89 references: 3.3.7, 3.2.1.5, 3.2.1.1.
>>
>> Hmm, unfortunately I don't have the c89 standard document. Can
>> somebody point me to the equvalent sections in c99?
>

>Integer promotions: 6.3.1.1.

Sentence 2 says "If an int can represent all values of the original
type, the value is converted to an int; otherwise, it is converted to
an unsigned int."

Seems to suggest that the conversion "unsigned short" to "signed int"
is ok.

But sentence 3 says "The integer promotions preserve value including
sign."

So shouldn't the conversion be "unsigned short" to "unsigned int"?

regards,
chris