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# size_max.m4 serial 2
dnl Copyright (C) 2003 Free Software Foundation, Inc.
dnl This file is free software, distributed under the terms of the GNU
dnl General Public License. As a special exception to the GNU General
dnl Public License, this file may be distributed as part of a program
dnl that contains a configuration script generated by Autoconf, under
dnl the same distribution terms as the rest of that program.
dnl From Bruno Haible.
AC_DEFUN([gl_SIZE_MAX],
[
AC_CHECK_HEADERS(stdint.h)
dnl First test whether the system already has SIZE_MAX.
AC_MSG_CHECKING([for SIZE_MAX])
result=
AC_EGREP_CPP([Found it], [
#include <limits.h>
#if HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef SIZE_MAX
Found it
#endif
], result=yes)
if test -z "$result"; then
dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
dnl than the type 'unsigned long'.
dnl The _AC_COMPUTE_INT macro works up to LONG_MAX, since it uses 'expr',
dnl which is guaranteed to work from LONG_MIN to LONG_MAX.
_AC_COMPUTE_INT([~(size_t)0 / 10], res_hi,
[#include <stddef.h>], result=?)
_AC_COMPUTE_INT([~(size_t)0 % 10], res_lo,
[#include <stddef.h>], result=?)
_AC_COMPUTE_INT([sizeof (size_t) <= sizeof (unsigned int)], fits_in_uint,
[#include <stddef.h>], result=?)
if test "$fits_in_uint" = 1; then
dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
AC_TRY_COMPILE([#include <stddef.h>
extern size_t foo;
extern unsigned long foo;
], [], fits_in_uint=0)
fi
if test -z "$result"; then
if test "$fits_in_uint" = 1; then
result="$res_hi$res_lo"U
else
result="$res_hi$res_lo"UL
fi
else
dnl Shouldn't happen, but who knows...
result='~(size_t)0'
fi
fi
AC_MSG_RESULT([$result])
if test "$result" != yes; then
AC_DEFINE_UNQUOTED([SIZE_MAX], [$result],
[Define as the maximum value of type 'size_t', if the system doesn't define it.])
fi
])
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