gl/intprops.h

   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 3 of the License, or
   8    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert.  */
  19
  20 #include <limits.h>
  21
  22 /* The extra casts in the following macros work around compiler bugs,
  23    e.g., in Cray C 5.0.3.0.  */
  24
  25 /* True if the arithmetic type T is an integer type.  bool counts as
  26    an integer.  */
  27 #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
  28
  29 /* True if negative values of the signed integer type T use two's
  30    complement, ones' complement, or signed magnitude representation,
  31    respectively.  Much GNU code assumes two's complement, but some
  32    people like to be portable to all possible C hosts.  */
  33 #define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
  34 #define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
  35 #define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
  36
  37 /* True if the arithmetic type T is signed.  */
  38 #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
  39
  40 /* The maximum and minimum values for the integer type T.  These
  41    macros have undefined behavior if T is signed and has padding bits.
  42    If this is a problem for you, please let us know how to fix it for
  43    your host.  */
  44 #define TYPE_MINIMUM(t) \
  45   ((t) (! TYPE_SIGNED (t) \
  46         ? (t) 0 \
  47         : TYPE_SIGNED_MAGNITUDE (t) \
  48         ? ~ (t) 0 \
  49         : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
  50 #define TYPE_MAXIMUM(t) \
  51   ((t) (! TYPE_SIGNED (t) \
  52         ? (t) -1 \
  53         : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
  54
  55 /* Return zero if T can be determined to be an unsigned type.
  56    Otherwise, return 1.
  57    When compiling with GCC, INT_STRLEN_BOUND uses this macro to obtain a
  58    tighter bound.  Otherwise, it overestimates the true bound by one byte
  59    when applied to unsigned types of size 2, 4, 16, ... bytes.
  60    The symbol signed_type_or_expr__ is private to this header file.  */
  61 #if __GNUC__ >= 2
  62 # define signed_type_or_expr__(t) TYPE_SIGNED (__typeof__ (t))
  63 #else
  64 # define signed_type_or_expr__(t) 1
  65 #endif
  66
  67 /* Bound on length of the string representing an integer type or expression T.
  68    Subtract 1 for the sign bit if T is signed; log10 (2.0) < 146/485;
  69    add 1 for integer division truncation; add 1 more for a minus sign
  70    if needed.  */
  71 #define INT_STRLEN_BOUND(t) \
  72   ((sizeof (t) * CHAR_BIT - signed_type_or_expr__ (t)) * 146 / 485 \
  73    + signed_type_or_expr__ (t) + 1)
  74
  75 /* Bound on buffer size needed to represent an integer type or expression T,
  76    including the terminating null.  */
  77 #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1)