|
Packit |
709fb3 |
# size_max.m4 serial 10
|
|
Packit |
709fb3 |
dnl Copyright (C) 2003, 2005-2006, 2008-2017 Free Software Foundation, Inc.
|
|
Packit |
709fb3 |
dnl This file is free software; the Free Software Foundation
|
|
Packit |
709fb3 |
dnl gives unlimited permission to copy and/or distribute it,
|
|
Packit |
709fb3 |
dnl with or without modifications, as long as this notice is preserved.
|
|
Packit |
709fb3 |
|
|
Packit |
709fb3 |
dnl From Bruno Haible.
|
|
Packit |
709fb3 |
|
|
Packit |
709fb3 |
AC_DEFUN([gl_SIZE_MAX],
|
|
Packit |
709fb3 |
[
|
|
Packit |
709fb3 |
AC_CHECK_HEADERS([stdint.h])
|
|
Packit |
709fb3 |
dnl First test whether the system already has SIZE_MAX.
|
|
Packit |
709fb3 |
AC_CACHE_CHECK([for SIZE_MAX], [gl_cv_size_max], [
|
|
Packit |
709fb3 |
gl_cv_size_max=
|
|
Packit |
709fb3 |
AC_EGREP_CPP([Found it], [
|
|
Packit |
709fb3 |
#include <limits.h>
|
|
Packit |
709fb3 |
#if HAVE_STDINT_H
|
|
Packit |
709fb3 |
#include <stdint.h>
|
|
Packit |
709fb3 |
#endif
|
|
Packit |
709fb3 |
#ifdef SIZE_MAX
|
|
Packit |
709fb3 |
Found it
|
|
Packit |
709fb3 |
#endif
|
|
Packit |
709fb3 |
], [gl_cv_size_max=yes])
|
|
Packit |
709fb3 |
if test -z "$gl_cv_size_max"; then
|
|
Packit |
709fb3 |
dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
|
|
Packit |
709fb3 |
dnl than the type 'unsigned long'. Try hard to find a definition that can
|
|
Packit |
709fb3 |
dnl be used in a preprocessor #if, i.e. doesn't contain a cast.
|
|
Packit |
709fb3 |
AC_COMPUTE_INT([size_t_bits_minus_1], [sizeof (size_t) * CHAR_BIT - 1],
|
|
Packit |
709fb3 |
[#include <stddef.h>
|
|
Packit |
709fb3 |
#include <limits.h>], [size_t_bits_minus_1=])
|
|
Packit |
709fb3 |
AC_COMPUTE_INT([fits_in_uint], [sizeof (size_t) <= sizeof (unsigned int)],
|
|
Packit |
709fb3 |
[#include <stddef.h>], [fits_in_uint=])
|
|
Packit |
709fb3 |
if test -n "$size_t_bits_minus_1" && test -n "$fits_in_uint"; then
|
|
Packit |
709fb3 |
if test $fits_in_uint = 1; then
|
|
Packit |
709fb3 |
dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
|
|
Packit |
709fb3 |
dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
|
|
Packit |
709fb3 |
AC_COMPILE_IFELSE(
|
|
Packit |
709fb3 |
[AC_LANG_PROGRAM(
|
|
Packit |
709fb3 |
[[#include <stddef.h>
|
|
Packit |
709fb3 |
extern size_t foo;
|
|
Packit |
709fb3 |
extern unsigned long foo;
|
|
Packit |
709fb3 |
]],
|
|
Packit |
709fb3 |
[[]])],
|
|
Packit |
709fb3 |
[fits_in_uint=0])
|
|
Packit |
709fb3 |
fi
|
|
Packit |
709fb3 |
dnl We cannot use 'expr' to simplify this expression, because 'expr'
|
|
Packit |
709fb3 |
dnl works only with 'long' integers in the host environment, while we
|
|
Packit |
709fb3 |
dnl might be cross-compiling from a 32-bit platform to a 64-bit platform.
|
|
Packit |
709fb3 |
if test $fits_in_uint = 1; then
|
|
Packit |
709fb3 |
gl_cv_size_max="(((1U << $size_t_bits_minus_1) - 1) * 2 + 1)"
|
|
Packit |
709fb3 |
else
|
|
Packit |
709fb3 |
gl_cv_size_max="(((1UL << $size_t_bits_minus_1) - 1) * 2 + 1)"
|
|
Packit |
709fb3 |
fi
|
|
Packit |
709fb3 |
else
|
|
Packit |
709fb3 |
dnl Shouldn't happen, but who knows...
|
|
Packit |
709fb3 |
gl_cv_size_max='((size_t)~(size_t)0)'
|
|
Packit |
709fb3 |
fi
|
|
Packit |
709fb3 |
fi
|
|
Packit |
709fb3 |
])
|
|
Packit |
709fb3 |
if test "$gl_cv_size_max" != yes; then
|
|
Packit |
709fb3 |
AC_DEFINE_UNQUOTED([SIZE_MAX], [$gl_cv_size_max],
|
|
Packit |
709fb3 |
[Define as the maximum value of type 'size_t', if the system doesn't define it.])
|
|
Packit |
709fb3 |
fi
|
|
Packit |
709fb3 |
dnl Don't redefine SIZE_MAX in config.h if config.h is re-included after
|
|
Packit |
709fb3 |
dnl <stdint.h>. Remember that the #undef in AH_VERBATIM gets replaced with
|
|
Packit |
709fb3 |
dnl #define by AC_DEFINE_UNQUOTED.
|
|
Packit |
709fb3 |
AH_VERBATIM([SIZE_MAX],
|
|
Packit |
709fb3 |
[/* Define as the maximum value of type 'size_t', if the system doesn't define
|
|
Packit |
709fb3 |
it. */
|
|
Packit |
709fb3 |
#ifndef SIZE_MAX
|
|
Packit |
709fb3 |
# undef SIZE_MAX
|
|
Packit |
709fb3 |
#endif])
|
|
Packit |
709fb3 |
])
|
|
Packit |
709fb3 |
|
|
Packit |
709fb3 |
dnl Autoconf >= 2.61 has AC_COMPUTE_INT built-in.
|
|
Packit |
709fb3 |
dnl Remove this when we can assume autoconf >= 2.61.
|
|
Packit |
709fb3 |
m4_ifdef([AC_COMPUTE_INT], [], [
|
|
Packit |
709fb3 |
AC_DEFUN([AC_COMPUTE_INT], [_AC_COMPUTE_INT([$2],[$1],[$3],[$4])])
|
|
Packit |
709fb3 |
])
|