-# size_max.m4 serial 2
-dnl Copyright (C) 2003 Free Software Foundation, Inc.
+# size_max.m4 serial 9
+dnl Copyright (C) 2003, 2005-2006, 2008-2010 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.
AC_DEFUN([gl_SIZE_MAX],
[
- AC_CHECK_HEADERS(stdint.h)
+ 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], [
+ 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>
#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
+], [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 << $size_t_bits_minus_1) - 1) * 2 + 1)"
+ fi
else
- result="$res_hi$res_lo"UL
+ dnl Shouldn't happen, but who knows...
+ gl_cv_size_max='((size_t)~(size_t)0)'
fi
- else
- dnl Shouldn't happen, but who knows...
- result='~(size_t)0'
fi
- fi
- AC_MSG_RESULT([$result])
- if test "$result" != yes; then
- AC_DEFINE_UNQUOTED([SIZE_MAX], [$result],
+ ])
+ 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])])
])