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[bug-gnulib] Re: length of dec. representation of a number
From: |
Paul Eggert |
Subject: |
[bug-gnulib] Re: length of dec. representation of a number |
Date: |
Wed, 09 Mar 2005 15:27:04 -0800 |
User-agent: |
Gnus/5.1006 (Gnus v5.10.6) Emacs/21.4 (gnu/linux) |
Stepan Kasal <address@hidden> writes:
> It took me some time to decipher the macros, perhaps we could document
> them more:
OK, and to avoid further confusion I ported them to signed-magnitude
hosts (not that I ever expect to see this tested :-).
I installed the following lib/intprops.h into gnulib and coreutils,
replacing the file I had installed earlier today.
/* intprops.h -- properties of integer types
Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Written by Paul Eggert. */
#include <limits.h>
/* The extra casts in the following macros work around compiler bugs,
e.g., in Cray C 5.0.3.0. */
/* True if the arithmetic type T is an integer type. bool counts as
an integer. */
#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
/* True if negative values of the signed integer type T use twos
complement, ones complement, or signed magnitude representation,
respectively. Much GNU code assumes twos complement, but some
people like to be portable to all possible C hosts. */
#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
/* True if the arithmetic type T is signed. */
#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
/* The maximum and minimum values for the integer type T. These
macros have undefined behavior if T is signed and has padding bits.
If this is a problem for you, please let us know how to fix it for
your host. */
#define TYPE_MINIMUM(t) \
((t) (! TYPE_SIGNED (t) \
? (t) 0 \
: TYPE_SIGNED_MAGNITUDE (t) \
? ~ (t) 0 \
: ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
#define TYPE_MAXIMUM(t) \
((t) (! TYPE_SIGNED (t) \
? (t) -1 \
: ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
/* Bound on length of the string representing an integer value or type T.
Subtract 1 for the sign bit if t is signed; log10 (2.0) < 146/485;
add 1 for integer division truncation; add 1 more for a minus sign
if needed. */
#define INT_STRLEN_BOUND(t) \
((sizeof (t) * CHAR_BIT - 1) * 146 / 485 + 2)
/* Bound on buffer size needed to represent an integer value or type T,
including the terminating null. */
#define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
- [bug-gnulib] Re: [bug-grep] length of dec. representation of a number, Paul Eggert, 2005/03/05
- [bug-gnulib] Re: length of dec. representation of a number, Stepan Kasal, 2005/03/07
- [bug-gnulib] Re: [bug-grep] length of dec. representation of a number, Jim Meyering, 2005/03/08
- [bug-gnulib] Re: [bug-grep] length of dec. representation of a number, Paul Jarc, 2005/03/09
- [bug-gnulib] Re: [bug-grep] length of dec. representation of a number, Jim Meyering, 2005/03/08
- Re: [bug-gnulib] Re: [bug-grep] length of dec. representation of a number, Stepan Kasal, 2005/03/09
- Re: [bug-gnulib] Re: [bug-grep] length of dec. representation of a number, Paul Jarc, 2005/03/09
- [bug-gnulib] Re: length of dec. representation of a number,
Paul Eggert <=
- [bug-gnulib] Re: length of dec. representation of a number, Paul Jarc, 2005/03/10
- [bug-gnulib] Re: [bug-grep] Re: length of dec. representation of a number, Jim Meyering, 2005/03/10
- Re: length of dec. representation of a number [bug-grep] [bug-gnulib], Stepan Kasal, 2005/03/10
- [bug-gnulib] Re: [bug-grep] Re: length of dec. representation of a number, Paul Jarc, 2005/03/10
- [bug-gnulib] Re: [bug-grep] Re: length of dec. representation of a number, Jim Meyering, 2005/03/10
- [bug-gnulib] Re: [bug-grep] Re: length of dec. representation of a number, Stepan Kasal, 2005/03/10
- [bug-gnulib] Re: [bug-grep] Re: length of dec. representation of a number, Paul Jarc, 2005/03/10
- [bug-gnulib] Re: [bug-grep] Re: length of dec. representation of a number, Paul Eggert, 2005/03/10