bits/wchar.h

   1 /* wchar_t type related definitions.
   2    Copyright (C) 2000-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _BITS_WCHAR_H
  20 #define _BITS_WCHAR_H   1
  21
  22 /* The fallback definitions, for when __WCHAR_MAX__ or __WCHAR_MIN__
  23    are not defined, give the right value and type as long as both int
  24    and wchar_t are 32-bit types.  Adding L'\0' to a constant value
  25    ensures that the type is correct; it is necessary to use (L'\0' +
  26    0) rather than just L'\0' so that the type in C++ is the promoted
  27    version of wchar_t rather than the distinct wchar_t type itself.
  28    Because wchar_t in preprocessor #if expressions is treated as
  29    intmax_t or uintmax_t, the expression (L'\0' - 1) would have the
  30    wrong value for WCHAR_MAX in such expressions and so cannot be used
  31    to define __WCHAR_MAX in the unsigned case.  */
  32
  33 #ifdef __WCHAR_MAX__
  34 # define __WCHAR_MAX    __WCHAR_MAX__
  35 #elif L'\0' - 1 > 0
  36 # define __WCHAR_MAX    (0xffffffffu + L'\0')
  37 #else
  38 # define __WCHAR_MAX    (0x7fffffff + L'\0')
  39 #endif
  40
  41 #ifdef __WCHAR_MIN__
  42 # define __WCHAR_MIN    __WCHAR_MIN__
  43 #elif L'\0' - 1 > 0
  44 # define __WCHAR_MIN    (L'\0' + 0)
  45 #else
  46 # define __WCHAR_MIN    (-__WCHAR_MAX - 1)
  47 #endif
  48
  49 #endif  /* bits/wchar.h */