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Re: Using the GNU GMP Library for Bignums in Emacs
From: |
Richard Stallman |
Subject: |
Re: Using the GNU GMP Library for Bignums in Emacs |
Date: |
Tue, 24 Apr 2018 21:05:55 -0400 |
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> 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.
- Re: Using the GNU GMP Library for Bignums in Emacs, (continued)
- Re: Using the GNU GMP Library for Bignums in Emacs, Richard Stallman, 2018/04/22
- Re: Using the GNU GMP Library for Bignums in Emacs, Helmut Eller, 2018/04/22
- Re: Using the GNU GMP Library for Bignums in Emacs, Paul Eggert, 2018/04/22
- Re: Using the GNU GMP Library for Bignums in Emacs, Richard Stallman, 2018/04/22
- Re: Using the GNU GMP Library for Bignums in Emacs, Paul Eggert, 2018/04/23
- Re: Using the GNU GMP Library for Bignums in Emacs, Richard Stallman, 2018/04/23
- Re: Using the GNU GMP Library for Bignums in Emacs, Paul Eggert, 2018/04/24
- Re: Using the GNU GMP Library for Bignums in Emacs, Helmut Eller, 2018/04/24
- Re: Using the GNU GMP Library for Bignums in Emacs,
Richard Stallman <=
- Re: Using the GNU GMP Library for Bignums in Emacs, Paul Eggert, 2018/04/24
- Re: Using the GNU GMP Library for Bignums in Emacs, Richard Stallman, 2018/04/25
- Re: Using the GNU GMP Library for Bignums in Emacs, Paul Eggert, 2018/04/25
- Re: Using the GNU GMP Library for Bignums in Emacs, Richard Stallman, 2018/04/29
- Re: Using the GNU GMP Library for Bignums in Emacs, Michael Welsh Duggan, 2018/04/30
- Re: Using the GNU GMP Library for Bignums in Emacs, Stefan Monnier, 2018/04/30
- Re: Using the GNU GMP Library for Bignums in Emacs, Richard Stallman, 2018/04/30
- Re: Using the GNU GMP Library for Bignums in Emacs, Paul Eggert, 2018/04/30
- Re: Using the GNU GMP Library for Bignums in Emacs, Richard Stallman, 2018/04/30
- Re: Using the GNU GMP Library for Bignums in Emacs, Richard Stallman, 2018/04/23