From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Richard Stallman Newsgroups: gmane.emacs.devel Subject: Re: Using the GNU GMP Library for Bignums in Emacs Date: Tue, 24 Apr 2018 21:05:55 -0400 Message-ID: References: <29f933ac-a6bf-8742-66a7-0a9d6d3e5a88@disroot.org> <83bmecy6fx.fsf@gnu.org> <0d3175d8-d996-651e-b221-71978bde3a65@cs.ucla.edu> <42cbc5ab-2f02-4aa5-4b19-7b2357f91692@cs.ucla.edu> <1f58acbf-a7d8-bf4e-3d0e-a285515a22e6@cs.ucla.edu> Reply-To: rms@gnu.org NNTP-Posting-Host: blaine.gmane.org Content-Type: text/plain; charset=Utf-8 X-Trace: blaine.gmane.org 1524618248 6270 195.159.176.226 (25 Apr 2018 01:04:08 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 25 Apr 2018 01:04:08 +0000 (UTC) Cc: eller.helmut@gmail.com, emacs-devel@gnu.org To: Paul Eggert Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Wed Apr 25 03:04:03 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fB8qo-0001Vt-CR for ged-emacs-devel@m.gmane.org; Wed, 25 Apr 2018 03:04:03 +0200 Original-Received: from localhost ([::1]:33254 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fB8sv-0006PU-3J for ged-emacs-devel@m.gmane.org; Tue, 24 Apr 2018 21:06:13 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:49966) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fB8si-0006P8-Sw for emacs-devel@gnu.org; Tue, 24 Apr 2018 21:06:02 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fB8sh-0005Gc-Q2 for emacs-devel@gnu.org; Tue, 24 Apr 2018 21:06:00 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:48767) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fB8se-0005Bc-4A; Tue, 24 Apr 2018 21:05:56 -0400 Original-Received: from rms by fencepost.gnu.org with local (Exim 4.82) (envelope-from ) id 1fB8sd-0008N1-OH; Tue, 24 Apr 2018 21:05:55 -0400 In-reply-to: <1f58acbf-a7d8-bf4e-3d0e-a285515a22e6@cs.ucla.edu> (message from Paul Eggert on Mon, 23 Apr 2018 21:35:31 -0700) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:224847 Archived-At: [[[ To any NSA and FBI agents reading my email: please consider ]]] [[[ whether defending the US Constitution against all enemies, ]]] [[[ foreign or domestic, requires you to follow Snowden's example. ]]] > In such applications, it's routine to have hexadecimal numbers that are wider > than 32- or 64-bit words. What is the motive for using hexadecimal in a case like that? > Even in the standard C library (which lacks bignums), the %x printf format is > supposed to be used only with unsigned integers. I think that's a misleading statement of what it does in C. The rule is to use it with an unsigned _type_. The type, not the value, is supposed to be unsigned. In practice, what this means is that the hex output is done _treating the number as unsigned_. So -1, which is 0xffffffff as a 32-bit int, will print as ffffffff, not as -1. I contend that we want the same behavior in Emacs Lisp, too. > If it turns out to be useful to have a shorthand printf format for formatting > the least N bits of an argument, we can add it as needed. I have my doubts, > though, as other bignum formatters seem to get along fine without such a feature. What conclusions we can draw from them, about Emacs Lisp, depends on the number of bits in a non-bignum integer for each of them. In Emacs, 0xffffffff will be a bignum. Is it a bignum in those other systems? If they can treat 32-bit ints as short, many programs that want to use hex will never operate on a bignum. -- Dr Richard Stallman President, Free Software Foundation (https://gnu.org, https://fsf.org) Internet Hall-of-Famer (https://internethalloffame.org) Skype: No way! See https://stallman.org/skype.html.