Annotation of embedaddon/confuse/m4/size_max.m4, revision 1.1.1.2
1.1.1.2 ! misho 1: # size_max.m4 serial 10
! 2: dnl Copyright (C) 2003, 2005-2006, 2008-2013 Free Software Foundation, Inc.
1.1 misho 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: [
1.1.1.2 ! misho 11: AC_CHECK_HEADERS([stdint.h])
1.1 misho 12: dnl First test whether the system already has SIZE_MAX.
1.1.1.2 ! misho 13: AC_CACHE_CHECK([for SIZE_MAX], [gl_cv_size_max], [
1.1 misho 14: gl_cv_size_max=
15: AC_EGREP_CPP([Found it], [
16: #include <limits.h>
17: #if HAVE_STDINT_H
18: #include <stdint.h>
19: #endif
20: #ifdef SIZE_MAX
21: Found it
22: #endif
1.1.1.2 ! misho 23: ], [gl_cv_size_max=yes])
1.1 misho 24: if test -z "$gl_cv_size_max"; then
25: dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
26: dnl than the type 'unsigned long'. Try hard to find a definition that can
27: dnl be used in a preprocessor #if, i.e. doesn't contain a cast.
1.1.1.2 ! misho 28: AC_COMPUTE_INT([size_t_bits_minus_1], [sizeof (size_t) * CHAR_BIT - 1],
1.1 misho 29: [#include <stddef.h>
1.1.1.2 ! misho 30: #include <limits.h>], [size_t_bits_minus_1=])
! 31: AC_COMPUTE_INT([fits_in_uint], [sizeof (size_t) <= sizeof (unsigned int)],
! 32: [#include <stddef.h>], [fits_in_uint=])
1.1 misho 33: if test -n "$size_t_bits_minus_1" && test -n "$fits_in_uint"; then
34: if test $fits_in_uint = 1; then
35: dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
36: dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
1.1.1.2 ! misho 37: AC_COMPILE_IFELSE(
! 38: [AC_LANG_PROGRAM(
! 39: [[#include <stddef.h>
! 40: extern size_t foo;
! 41: extern unsigned long foo;
! 42: ]],
! 43: [[]])],
! 44: [fits_in_uint=0])
1.1 misho 45: fi
46: dnl We cannot use 'expr' to simplify this expression, because 'expr'
47: dnl works only with 'long' integers in the host environment, while we
48: dnl might be cross-compiling from a 32-bit platform to a 64-bit platform.
49: if test $fits_in_uint = 1; then
50: gl_cv_size_max="(((1U << $size_t_bits_minus_1) - 1) * 2 + 1)"
51: else
52: gl_cv_size_max="(((1UL << $size_t_bits_minus_1) - 1) * 2 + 1)"
53: fi
54: else
55: dnl Shouldn't happen, but who knows...
56: gl_cv_size_max='((size_t)~(size_t)0)'
57: fi
58: fi
59: ])
60: if test "$gl_cv_size_max" != yes; then
61: AC_DEFINE_UNQUOTED([SIZE_MAX], [$gl_cv_size_max],
62: [Define as the maximum value of type 'size_t', if the system doesn't define it.])
63: fi
1.1.1.2 ! misho 64: dnl Don't redefine SIZE_MAX in config.h if config.h is re-included after
! 65: dnl <stdint.h>. Remember that the #undef in AH_VERBATIM gets replaced with
! 66: dnl #define by AC_DEFINE_UNQUOTED.
! 67: AH_VERBATIM([SIZE_MAX],
! 68: [/* Define as the maximum value of type 'size_t', if the system doesn't define
! 69: it. */
! 70: #ifndef SIZE_MAX
! 71: # undef SIZE_MAX
! 72: #endif])
! 73: ])
! 74:
! 75: dnl Autoconf >= 2.61 has AC_COMPUTE_INT built-in.
! 76: dnl Remove this when we can assume autoconf >= 2.61.
! 77: m4_ifdef([AC_COMPUTE_INT], [], [
! 78: AC_DEFUN([AC_COMPUTE_INT], [_AC_COMPUTE_INT([$2],[$1],[$3],[$4])])
1.1 misho 79: ])
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