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1/* intprops.h -- properties of integer types
2
3 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
8 any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
18
19/* Written by Paul Eggert. */
20
21#include <limits.h>
22
23/* The extra casts in the following macros work around compiler bugs,
24 e.g., in Cray C 5.0.3.0. */
25
26/* True if the arithmetic type T is an integer type. bool counts as
27 an integer. */
28#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
29
30/* True if negative values of the signed integer type T use two's
31 complement, ones' complement, or signed magnitude representation,
32 respectively. Much GNU code assumes two's complement, but some
33 people like to be portable to all possible C hosts. */
34#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
35#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
36#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
37
38/* True if the arithmetic type T is signed. */
39#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
40
41/* The maximum and minimum values for the integer type T. These
42 macros have undefined behavior if T is signed and has padding bits.
43 If this is a problem for you, please let us know how to fix it for
44 your host. */
45#define TYPE_MINIMUM(t) \
46 ((t) (! TYPE_SIGNED (t) \
47 ? (t) 0 \
48 : TYPE_SIGNED_MAGNITUDE (t) \
49 ? ~ (t) 0 \
50 : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
51#define TYPE_MAXIMUM(t) \
52 ((t) (! TYPE_SIGNED (t) \
53 ? (t) -1 \
54 : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
55
56/* Return zero if T can be determined to be an unsigned type.
57 Otherwise, return 1.
58 When compiling with GCC, INT_STRLEN_BOUND uses this macro to obtain a
59 tighter bound. Otherwise, it overestimates the true bound by one byte
60 when applied to unsigned types of size 2, 4, 16, ... bytes.
61 The symbol signed_type_or_expr__ is private to this header file. */
62#if __GNUC__ >= 2
63# define signed_type_or_expr__(t) TYPE_SIGNED (__typeof__ (t))
64#else
65# define signed_type_or_expr__(t) 1
66#endif
67
68/* Bound on length of the string representing an integer type or expression T.
69 Subtract 1 for the sign bit if T is signed; log10 (2.0) < 146/485;
70 add 1 for integer division truncation; add 1 more for a minus sign
71 if needed. */
72#define INT_STRLEN_BOUND(t) \
73 ((sizeof (t) * CHAR_BIT - signed_type_or_expr__ (t)) * 146 / 485 \
74 + signed_type_or_expr__ (t) + 1)
75
76/* Bound on buffer size needed to represent an integer type or expression T,
77 including the terminating null. */
78#define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)