220 21438 <561a7ad2-1b25-47e1-8aaf-b3fe53d52e95@isocpp.org> article Path: news.gmane.org!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: alias_ptr, restrict_ptr, unaligned_ptr Date: Thu, 8 Oct 2015 08:29:21 -0700 (PDT) Lines: 77 Approved: news@gmane.org Message-ID: <561a7ad2-1b25-47e1-8aaf-b3fe53d52e95@isocpp.org> References: <2377636.q9WPHpPlTT@tjmaciei-mobl4> <73acad8c-5bb0-4c97-ada1-833b55af0be6@isocpp.org> <2270922.AyAy1RJ3rj@tjmaciei-mobl4> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_143_60555611.1444318161503" X-Trace: ger.gmane.org 1444318172 26931 80.91.229.3 (8 Oct 2015 15:29:32 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 8 Oct 2015 15:29:32 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBBUUX3KYAKGQEBFSEF7I@isocpp.org Thu Oct 08 17:29:32 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vk0-f72.google.com ([209.85.213.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZkD8L-0005dq-2H for gclcip-std-proposals@m.gmane.org; Thu, 08 Oct 2015 17:29:29 +0200 Original-Received: by vkao3 with SMTP id o3sf80164164vka.1 for ; Thu, 08 Oct 2015 08:29:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :content-type:x-original-sender:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=6fOLF4rHlIDyny1MxYBeoe6R0/bp3wR/16d2gs+gRv8=; b=AwP20xuSQ+GxEjbWgEivVNFcUXSjOZmzHljb4B1M+XhJTIMw+76mcrMlsYmKBqmeVZ zMBXfIiVpc1xjuVKM0ekm31YyQ4KYb55ZNJsz895RKe9hmGfDAyuMiogpO8vZab2ulT+ keUt93FgOSqQdEKo2sEl+DNmRuuYLm7IdrH/06y6cK1ICgWGKJiWEG9JWb+H/RQjNk3c cpEEu32I3LGoUlBjAW9CPEhSzt1gYxr+NoyvYx4ptpEDVQVUYly4+auNNFrOBth9V5tp KaSI0s2Olsy2s+dJk2x8Rv5IA9NfrXDF2gJem4xUeDvoZG8qJA5ToI9W57pN978lcmX5 deIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:content-type:x-original-sender:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=6fOLF4rHlIDyny1MxYBeoe6R0/bp3wR/16d2gs+gRv8=; b=Qv0UyzuVoL50UT8kN2kH/Ou8qg+LhYQ5ZqLfZ3dx7lLQbBrigtAc8N+kQPD/7QVt2R WKvR6cEUVO6QAYO/Hximfp7+RXoulqJwE66N+2Me/WK33XHS8VN4AZgoDjxopMNcYzCK PI99foypsNDFZMuJmcX6e2/cLm0xXZUHiSV8YrWElWkQ5CAVFWtM3nFfL0AHYxlb4xbj yVwQTqdxLbu9QDF8Wygtk5PfAWX/h+ZkS44HVvAJds+Hoeq/QyQ0ymnejCPrv7unNNGm AXTloum1TCjRUPDcjlbnr/lN1Z8KCobEuJn2mXZZ674Sr6ch3dOSBYTC6Pm6rsOlgI/f 9Wrg== X-Gm-Message-State: ALoCoQmhmE0k7NXMrO3Y4QxyQLCOnZfSBxSjoFLwYfwEq+j9zjFzU/LEiHWUYgYBR1PUk65w2Bvn X-Received: by 10.31.108.28 with SMTP id h28mr6450509vkc.4.1444318162957; Thu, 08 Oct 2015 08:29:22 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.164.16 with SMTP id n16ls586827ioe.80.gmail; Thu, 08 Oct 2015 08:29:22 -0700 (PDT) X-Received: by 10.50.131.164 with SMTP id on4mr55892igb.8.1444318162040; Thu, 08 Oct 2015 08:29:22 -0700 (PDT) In-Reply-To: <2270922.AyAy1RJ3rj@tjmaciei-mobl4> X-Original-Sender: jmckesson@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:21438 Archived-At: ------=_Part_143_60555611.1444318161503 Content-Type: multipart/alternative; boundary="----=_Part_144_1946915551.1444318161503" ------=_Part_144_1946915551.1444318161503 Content-Type: text/plain; charset=UTF-8 On Thursday, October 8, 2015 at 11:24:39 AM UTC-4, Thiago Macieira wrote: > > On Thursday 08 October 2015 05:53:31 Nicol Bolas wrote: > > However, IEEE-754 would still be a bit... dubious. There are many ARM > > platforms that have to emulate floats in software. At the very least, > there > > should be a way to test whether floats are real IEEE-754 or emulated. > > I don't think that's a problem. Most emulations do use IEEE 754 too, so > they'd > fulfil the requirement. > Yes, but how *exact* are they? Do they provide the exact (within the tolerances of the spec) precision required for IEEE-754, 32-bit precision? I imagine most of them cut corners and are willing to burn a digit or 3's precision to get a faster answer. -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. 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On Thursday, October 8, 2015 at 11:24:39 AM UTC-4,= Thiago Macieira wrote:
On Thur= sday 08 October 2015 05:53:31 Nicol Bolas wrote:
> However, IEEE-754 would still be a bit... dubious. There are many = ARM=20
> platforms that have to emulate floats in software. At the very lea= st, there=20
> should be a way to test whether floats are real IEEE-754 or emulat= ed.

I don't think that's a problem. Most emulations do use IEEE 754= too, so they'd=20
fulfil the requirement.

Yes, but how exact<= /i> are they? Do they provide the exact (within the tolerances of the spec)= precision required for IEEE-754, 32-bit precision? I imagine most of them = cut corners and are willing to burn a digit or 3's precision to get a f= aster answer.

--

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