1 /* intprops.h -- properties of integer types 2 3 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009, 2010 Free Software 4 Foundation, Inc. 5 6 This program is free software: you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3 of the License, or 9 (at your option) any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 18 19 /* Written by Paul Eggert. */ 20 21 #ifndef GL_INTPROPS_H 22 # define GL_INTPROPS_H 23 24 # include <limits.h> 25 26 /* The extra casts in the following macros work around compiler bugs, 27 e.g., in Cray C 5.0.3.0. */ 28 29 /* True if the arithmetic type T is an integer type. bool counts as 30 an integer. */ 31 # define TYPE_IS_INTEGER(t) ((t) 1.5 == 1) 32 33 /* True if negative values of the signed integer type T use two's 34 complement, ones' complement, or signed magnitude representation, 35 respectively. Much GNU code assumes two's complement, but some 36 people like to be portable to all possible C hosts. */ 37 # define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1) 38 # define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0) 39 # define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1) 40 41 /* True if the arithmetic type T is signed. */ 42 # define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) 43 44 /* The maximum and minimum values for the integer type T. These 45 macros have undefined behavior if T is signed and has padding bits. 46 If this is a problem for you, please let us know how to fix it for 47 your host. */ 48 # define TYPE_MINIMUM(t) \ 49 ((t) (! TYPE_SIGNED (t) \ 50 ? (t) 0 \ 51 : TYPE_SIGNED_MAGNITUDE (t) \ 52 ? ~ (t) 0 \ 53 : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))) 54 # define TYPE_MAXIMUM(t) \ 55 ((t) (! TYPE_SIGNED (t) \ 56 ? (t) -1 \ 57 : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))) 58 59 /* Return zero if T can be determined to be an unsigned type. 60 Otherwise, return 1. 61 When compiling with GCC, INT_STRLEN_BOUND uses this macro to obtain a 62 tighter bound. Otherwise, it overestimates the true bound by one byte 63 when applied to unsigned types of size 2, 4, 16, ... bytes. 64 The symbol signed_type_or_expr__ is private to this header file. */ 65 # if __GNUC__ >= 2 66 # define signed_type_or_expr__(t) TYPE_SIGNED (__typeof__ (t)) 67 # else 68 # define signed_type_or_expr__(t) 1 69 # endif 70 71 /* Bound on length of the string representing an integer type or expression T. 72 Subtract 1 for the sign bit if T is signed; log10 (2.0) < 146/485; 73 add 1 for integer division truncation; add 1 more for a minus sign 74 if needed. */ 75 # define INT_STRLEN_BOUND(t) \ 76 ((sizeof (t) * CHAR_BIT - signed_type_or_expr__ (t)) * 146 / 485 \ 77 + signed_type_or_expr__ (t) + 1) 78 79 /* Bound on buffer size needed to represent an integer type or expression T, 80 including the terminating null. */ 81 # define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1) 82 83 #endif /* GL_INTPROPS_H */ 84