Annotation of embedaddon/confuse/m4/size_max.m4, revision 1.1
1.1 ! misho 1: # size_max.m4 serial 5
! 2: dnl Copyright (C) 2003, 2005-2006 Free Software Foundation, Inc.
! 3: dnl This file is free software; the Free Software Foundation
! 4: dnl gives unlimited permission to copy and/or distribute it,
! 5: dnl with or without modifications, as long as this notice is preserved.
! 6:
! 7: dnl From Bruno Haible.
! 8:
! 9: AC_DEFUN([gl_SIZE_MAX],
! 10: [
! 11: AC_CHECK_HEADERS(stdint.h)
! 12: dnl First test whether the system already has SIZE_MAX.
! 13: AC_MSG_CHECKING([for SIZE_MAX])
! 14: AC_CACHE_VAL([gl_cv_size_max], [
! 15: gl_cv_size_max=
! 16: AC_EGREP_CPP([Found it], [
! 17: #include <limits.h>
! 18: #if HAVE_STDINT_H
! 19: #include <stdint.h>
! 20: #endif
! 21: #ifdef SIZE_MAX
! 22: Found it
! 23: #endif
! 24: ], gl_cv_size_max=yes)
! 25: if test -z "$gl_cv_size_max"; then
! 26: dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
! 27: dnl than the type 'unsigned long'. Try hard to find a definition that can
! 28: dnl be used in a preprocessor #if, i.e. doesn't contain a cast.
! 29: _AC_COMPUTE_INT([sizeof (size_t) * CHAR_BIT - 1], size_t_bits_minus_1,
! 30: [#include <stddef.h>
! 31: #include <limits.h>], size_t_bits_minus_1=)
! 32: _AC_COMPUTE_INT([sizeof (size_t) <= sizeof (unsigned int)], fits_in_uint,
! 33: [#include <stddef.h>], fits_in_uint=)
! 34: if test -n "$size_t_bits_minus_1" && test -n "$fits_in_uint"; then
! 35: if test $fits_in_uint = 1; then
! 36: dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
! 37: dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
! 38: AC_TRY_COMPILE([#include <stddef.h>
! 39: extern size_t foo;
! 40: extern unsigned long foo;
! 41: ], [], fits_in_uint=0)
! 42: fi
! 43: dnl We cannot use 'expr' to simplify this expression, because 'expr'
! 44: dnl works only with 'long' integers in the host environment, while we
! 45: dnl might be cross-compiling from a 32-bit platform to a 64-bit platform.
! 46: if test $fits_in_uint = 1; then
! 47: gl_cv_size_max="(((1U << $size_t_bits_minus_1) - 1) * 2 + 1)"
! 48: else
! 49: gl_cv_size_max="(((1UL << $size_t_bits_minus_1) - 1) * 2 + 1)"
! 50: fi
! 51: else
! 52: dnl Shouldn't happen, but who knows...
! 53: gl_cv_size_max='((size_t)~(size_t)0)'
! 54: fi
! 55: fi
! 56: ])
! 57: AC_MSG_RESULT([$gl_cv_size_max])
! 58: if test "$gl_cv_size_max" != yes; then
! 59: AC_DEFINE_UNQUOTED([SIZE_MAX], [$gl_cv_size_max],
! 60: [Define as the maximum value of type 'size_t', if the system doesn't define it.])
! 61: fi
! 62: ])
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>