mirror of
git://git.gnupg.org/gnupg.git
synced 2024-10-31 20:08:43 +01:00
63 lines
2.4 KiB
Plaintext
63 lines
2.4 KiB
Plaintext
# size_max.m4 serial 5
|
|
dnl Copyright (C) 2003, 2005-2006 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_MSG_CHECKING([for SIZE_MAX])
|
|
AC_CACHE_VAL([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 "$gl_cv_size_max"; then
|
|
dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
|
|
dnl than the type 'unsigned long'. Try hard to find a definition that can
|
|
dnl be used in a preprocessor #if, i.e. doesn't contain a cast.
|
|
_AC_COMPUTE_INT([sizeof (size_t) * CHAR_BIT - 1], size_t_bits_minus_1,
|
|
[#include <stddef.h>
|
|
#include <limits.h>], size_t_bits_minus_1=)
|
|
_AC_COMPUTE_INT([sizeof (size_t) <= sizeof (unsigned int)], fits_in_uint,
|
|
[#include <stddef.h>], fits_in_uint=)
|
|
if test -n "$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 << $size_t_bits_minus_1) - 1) * 2 + 1)"
|
|
fi
|
|
else
|
|
dnl Shouldn't happen, but who knows...
|
|
gl_cv_size_max='((size_t)~(size_t)0)'
|
|
fi
|
|
fi
|
|
])
|
|
AC_MSG_RESULT([$gl_cv_size_max])
|
|
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
|
|
])
|