2 dnl Copyright (C) 2003 Free Software Foundation, Inc.
3 dnl This file is free software, distributed under the terms of the GNU
4 dnl General Public License. As a special exception to the GNU General
5 dnl Public License, this file may be distributed as part of a program
6 dnl that contains a configuration script generated by Autoconf, under
7 dnl the same distribution terms as the rest of that program.
11 AC_DEFUN([gl_SIZE_MAX],
13 AC_CHECK_HEADERS(stdint.h)
14 dnl First test whether the system already has SIZE_MAX.
15 AC_MSG_CHECKING([for SIZE_MAX])
17 AC_EGREP_CPP([Found it], [
26 if test -z "$result"; then
27 dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
28 dnl than the type 'unsigned long'.
29 dnl The _AC_COMPUTE_INT macro works up to LONG_MAX, since it uses 'expr',
30 dnl which is guaranteed to work from LONG_MIN to LONG_MAX.
31 _AC_COMPUTE_INT([~(size_t)0 / 10], res_hi,
32 [#include <stddef.h>], result=?)
33 _AC_COMPUTE_INT([~(size_t)0 % 10], res_lo,
34 [#include <stddef.h>], result=?)
35 _AC_COMPUTE_INT([sizeof (size_t) <= sizeof (unsigned int)], fits_in_uint,
36 [#include <stddef.h>], result=?)
37 if test "$fits_in_uint" = 1; then
38 dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
39 dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
40 AC_TRY_COMPILE([#include <stddef.h>
42 extern unsigned long foo;
43 ], [], fits_in_uint=0)
45 if test -z "$result"; then
46 if test "$fits_in_uint" = 1; then
47 result="$res_hi$res_lo"U
49 result="$res_hi$res_lo"UL
52 dnl Shouldn't happen, but who knows...
56 AC_MSG_RESULT([$result])
57 if test "$result" != yes; then
58 AC_DEFINE_UNQUOTED([SIZE_MAX], [$result],
59 [Define as the maximum value of type 'size_t', if the system doesn't define it.])