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272
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1 /* intprops.h -- properties of integer types
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2
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3 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
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4
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5 This program is free software: you can redistribute it and/or modify
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6 it under the terms of the GNU General Public License as published by
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7 the Free Software Foundation; either version 3 of the License, or
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8 (at your option) any later version.
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9
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10 This program is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 GNU General Public License for more details.
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14
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15 You should have received a copy of the GNU General Public License
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16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
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17
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18 /* Written by Paul Eggert. */
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19
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20 #include <limits.h>
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21
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22 /* The extra casts in the following macros work around compiler bugs,
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23 e.g., in Cray C 5.0.3.0. */
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24
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25 /* True if the arithmetic type T is an integer type. bool counts as
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26 an integer. */
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27 #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
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28
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29 /* True if negative values of the signed integer type T use two's
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30 complement, ones' complement, or signed magnitude representation,
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31 respectively. Much GNU code assumes two's complement, but some
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32 people like to be portable to all possible C hosts. */
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33 #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
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34 #define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
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35 #define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
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36
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37 /* True if the arithmetic type T is signed. */
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38 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
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39
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40 /* The maximum and minimum values for the integer type T. These
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41 macros have undefined behavior if T is signed and has padding bits.
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42 If this is a problem for you, please let us know how to fix it for
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43 your host. */
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44 #define TYPE_MINIMUM(t) \
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45 ((t) (! TYPE_SIGNED (t) \
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46 ? (t) 0 \
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47 : TYPE_SIGNED_MAGNITUDE (t) \
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48 ? ~ (t) 0 \
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49 : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
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50 #define TYPE_MAXIMUM(t) \
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51 ((t) (! TYPE_SIGNED (t) \
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52 ? (t) -1 \
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53 : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
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54
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55 /* Return zero if T can be determined to be an unsigned type.
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56 Otherwise, return 1.
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57 When compiling with GCC, INT_STRLEN_BOUND uses this macro to obtain a
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58 tighter bound. Otherwise, it overestimates the true bound by one byte
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59 when applied to unsigned types of size 2, 4, 16, ... bytes.
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60 The symbol signed_type_or_expr__ is private to this header file. */
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61 #if __GNUC__ >= 2
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62 # define signed_type_or_expr__(t) TYPE_SIGNED (__typeof__ (t))
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63 #else
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64 # define signed_type_or_expr__(t) 1
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65 #endif
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66
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67 /* Bound on length of the string representing an integer type or expression T.
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68 Subtract 1 for the sign bit if T is signed; log10 (2.0) < 146/485;
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69 add 1 for integer division truncation; add 1 more for a minus sign
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70 if needed. */
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71 #define INT_STRLEN_BOUND(t) \
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72 ((sizeof (t) * CHAR_BIT - signed_type_or_expr__ (t)) * 146 / 485 \
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73 + signed_type_or_expr__ (t) + 1)
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74
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75 /* Bound on buffer size needed to represent an integer type or expression T,
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76 including the terminating null. */
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77 #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)
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