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+# size_max.m4 serial 9
+dnl Copyright (C) 2003, 2005-2006, 2008-2009 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+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_CACHE_CHECK([for SIZE_MAX], [gl_cv_size_max], [
+ gl_cv_size_max=
+ AC_EGREP_CPP([Found it], [
+#include <limits.h>
+#if HAVE_STDINT_H
+#include <stdint.h>
+#endif
+#ifdef SIZE_MAX
+Found it
+#endif
+], [gl_cv_size_max=yes])
+ if test -z "$gl_cv_size_max"; then
+ dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
+ dnl than the type 'unsigned long'. Try hard to find a definition that can
+ dnl be used in a preprocessor #if, i.e. doesn't contain a cast.
+ AC_COMPUTE_INT([size_t_bits_minus_1], [sizeof (size_t) * CHAR_BIT - 1],
+ [#include <stddef.h>
+#include <limits.h>], [size_t_bits_minus_1=])
+ AC_COMPUTE_INT([fits_in_uint], [sizeof (size_t) <= sizeof (unsigned int)],
+ [#include <stddef.h>], [fits_in_uint=])
+ if test -n "$size_t_bits_minus_1" && test -n "$fits_in_uint"; then
+ 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
+ dnl We cannot use 'expr' to simplify this expression, because 'expr'
+ dnl works only with 'long' integers in the host environment, while we
+ dnl might be cross-compiling from a 32-bit platform to a 64-bit platform.
+ if test $fits_in_uint = 1; then
+ gl_cv_size_max="(((1U << $size_t_bits_minus_1) - 1) * 2 + 1)"
+ else
+ gl_cv_size_max="(((1UL << $size_t_bits_minus_1) - 1) * 2 + 1)"
+ fi
+ else
+ dnl Shouldn't happen, but who knows...
+ gl_cv_size_max='((size_t)~(size_t)0)'
+ fi
+ fi
+ ])
+ if test "$gl_cv_size_max" != yes; then
+ AC_DEFINE_UNQUOTED([SIZE_MAX], [$gl_cv_size_max],
+ [Define as the maximum value of type 'size_t', if the system doesn't define it.])
+ fi
+ dnl Don't redefine SIZE_MAX in config.h if config.h is re-included after
+ dnl <stdint.h>. Remember that the #undef in AH_VERBATIM gets replaced with
+ dnl #define by AC_DEFINE_UNQUOTED.
+ AH_VERBATIM([SIZE_MAX],
+[/* Define as the maximum value of type 'size_t', if the system doesn't define
+ it. */
+#ifndef SIZE_MAX
+# undef SIZE_MAX
+#endif])
+])
+
+dnl Autoconf >= 2.61 has AC_COMPUTE_INT built-in.
+dnl Remove this when we can assume autoconf >= 2.61.
+m4_ifdef([AC_COMPUTE_INT], [], [
+ AC_DEFUN([AC_COMPUTE_INT], [_AC_COMPUTE_INT([$2],[$1],[$3],[$4])])
+])