From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12499 invoked by alias); 26 Aug 2015 11:44:53 -0000 Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org Received: (qmail 12457 invoked by uid 89); 26 Aug 2015 11:44:52 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.3 required=5.0 tests=AWL,BAYES_50,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-io0-f171.google.com Received: from mail-io0-f171.google.com (HELO mail-io0-f171.google.com) (209.85.223.171) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Wed, 26 Aug 2015 11:44:50 +0000 Received: by iods203 with SMTP id s203so14976651iod.0 for ; Wed, 26 Aug 2015 04:44:48 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.107.14.73 with SMTP id 70mr3247871ioo.11.1440589488422; Wed, 26 Aug 2015 04:44:48 -0700 (PDT) Received: by 10.36.123.215 with HTTP; Wed, 26 Aug 2015 04:44:48 -0700 (PDT) Reply-To: noloader@gmail.com In-Reply-To: <1B1111BE-E274-4C80-8189-22B78D77647A@gmail.com> References: <1B1111BE-E274-4C80-8189-22B78D77647A@gmail.com> Date: Wed, 26 Aug 2015 11:44:00 -0000 Message-ID: Subject: Re: 128-bit integer - nonsensical documentation? From: Jeffrey Walton To: Kostas Savvidis Cc: "gcc-help@gcc.gnu.org" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes X-SW-Source: 2015-08/txt/msg00177.txt.bz2 On Wed, Aug 26, 2015 at 7:04 AM, Kostas Savvidis wrot= e: > The online documentation contains the attached passage as part of the "C-= Extensions=E2=80=9D chapter. There are no actual machines which have an " i= nteger mode wide enough to hold 128 bits=E2=80=9D as the document puts it. = This would be a harmless confusion if it didn=E2=80=99t go on to say =E2=80= =9C=E2=80=A6 long long integer less than 128 bits wide=E2=80=9D (???!!!) Wh= ereas in reality "long long int=E2=80=9D is 64 bits everywhere i have seen. > On 64-bit platforms, a 128-bit integer is available. I don't know how widespread it is, but its available on the Intel Mac I use and some of my P4 machines. When using OpenSSL, if you configure with enable-ec_nistp_64_gcc_128, then Elliptic Curve Diffie-Hellman is about 2x to 4x faster. You have to enable enable-ec_nistp_64_gcc_128 manually because OpenSSL's configure cannot detect it. See, for example https://wiki.openssl.org/index.php/Compilation_and_Installation. Jeff