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 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)