1 /* intprops.h -- properties of integer types
3 Copyright (C) 2001-2005, 2009-2011 Free Software Foundation, Inc.
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 3 of the License, or
8 (at your option) any later version.
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.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 /* Written by Paul Eggert. */
20 #ifndef _GL_INTPROPS_H
21 #define _GL_INTPROPS_H
25 /* The extra casts in the following macros work around compiler bugs,
26 e.g., in Cray C 5.0.3.0. */
28 /* True if the arithmetic type T is an integer type. bool counts as
30 #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
32 /* True if negative values of the signed integer type T use two's
33 complement, ones' complement, or signed magnitude representation,
34 respectively. Much GNU code assumes two's complement, but some
35 people like to be portable to all possible C hosts. */
36 #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
37 #define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
38 #define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
40 /* True if the arithmetic type T is signed. */
41 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
43 /* The maximum and minimum values for the integer type T. These
44 macros have undefined behavior if T is signed and has padding bits.
45 If this is a problem for you, please let us know how to fix it for
47 #define TYPE_MINIMUM(t) \
48 ((t) (! TYPE_SIGNED (t) \
50 : TYPE_SIGNED_MAGNITUDE (t) \
52 : ~ TYPE_MAXIMUM (t)))
53 #define TYPE_MAXIMUM(t) \
54 ((t) (! TYPE_SIGNED (t) \
56 : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1)))
58 /* Return 1 if the __typeof__ keyword works. This could be done by
59 'configure', but for now it's easier to do it by hand. */
60 #if 2 <= __GNUC__ || 0x5110 <= __SUNPRO_C
61 # define _GL_HAVE___TYPEOF__ 1
63 # define _GL_HAVE___TYPEOF__ 0
66 /* Return 1 if the integer type or expression T might be signed. Return 0
67 if it is definitely unsigned. This macro does not evaluate its argument,
68 and expands to an integer constant expression. */
69 #if _GL_HAVE___TYPEOF__
70 # define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t))
72 # define _GL_SIGNED_TYPE_OR_EXPR(t) 1
75 /* Bound on length of the string representing an unsigned integer
76 value representable in B bits. log10 (2.0) < 146/485. The
77 smallest value of B where this bound is not tight is 2621. */
78 #define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485)
80 /* Bound on length of the string representing an integer type or expression T.
81 Subtract 1 for the sign bit if T is signed, and then add 1 more for
82 a minus sign if needed.
84 Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 0 when its argument is
85 signed, this macro may overestimate the true bound by one byte when
86 applied to unsigned types of size 2, 4, 16, ... bytes. */
87 #define INT_STRLEN_BOUND(t) \
88 (INT_BITS_STRLEN_BOUND (sizeof (t) * CHAR_BIT \
89 - _GL_SIGNED_TYPE_OR_EXPR (t)) \
90 + _GL_SIGNED_TYPE_OR_EXPR (t))
92 /* Bound on buffer size needed to represent an integer type or expression T,
93 including the terminating null. */
94 #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
96 #endif /* _GL_INTPROPS_H */