diff options
Diffstat (limited to 'm4/size_max.m4')
-rw-r--r-- | m4/size_max.m4 | 102 |
1 files changed, 60 insertions, 42 deletions
diff --git a/m4/size_max.m4 b/m4/size_max.m4 index 5762fc33..7e192d5e 100644 --- a/m4/size_max.m4 +++ b/m4/size_max.m4 | |||
@@ -1,20 +1,18 @@ | |||
1 | # size_max.m4 serial 2 | 1 | # size_max.m4 serial 10 |
2 | dnl Copyright (C) 2003 Free Software Foundation, Inc. | 2 | dnl Copyright (C) 2003, 2005-2006, 2008-2014 Free Software Foundation, Inc. |
3 | dnl This file is free software, distributed under the terms of the GNU | 3 | dnl This file is free software; the Free Software Foundation |
4 | dnl General Public License. As a special exception to the GNU General | 4 | dnl gives unlimited permission to copy and/or distribute it, |
5 | dnl Public License, this file may be distributed as part of a program | 5 | dnl with or without modifications, as long as this notice is preserved. |
6 | dnl that contains a configuration script generated by Autoconf, under | ||
7 | dnl the same distribution terms as the rest of that program. | ||
8 | 6 | ||
9 | dnl From Bruno Haible. | 7 | dnl From Bruno Haible. |
10 | 8 | ||
11 | AC_DEFUN([gl_SIZE_MAX], | 9 | AC_DEFUN([gl_SIZE_MAX], |
12 | [ | 10 | [ |
13 | AC_CHECK_HEADERS(stdint.h) | 11 | AC_CHECK_HEADERS([stdint.h]) |
14 | dnl First test whether the system already has SIZE_MAX. | 12 | dnl First test whether the system already has SIZE_MAX. |
15 | AC_MSG_CHECKING([for SIZE_MAX]) | 13 | AC_CACHE_CHECK([for SIZE_MAX], [gl_cv_size_max], [ |
16 | result= | 14 | gl_cv_size_max= |
17 | AC_EGREP_CPP([Found it], [ | 15 | AC_EGREP_CPP([Found it], [ |
18 | #include <limits.h> | 16 | #include <limits.h> |
19 | #if HAVE_STDINT_H | 17 | #if HAVE_STDINT_H |
20 | #include <stdint.h> | 18 | #include <stdint.h> |
@@ -22,40 +20,60 @@ AC_DEFUN([gl_SIZE_MAX], | |||
22 | #ifdef SIZE_MAX | 20 | #ifdef SIZE_MAX |
23 | Found it | 21 | Found it |
24 | #endif | 22 | #endif |
25 | ], result=yes) | 23 | ], [gl_cv_size_max=yes]) |
26 | if test -z "$result"; then | 24 | if test -z "$gl_cv_size_max"; then |
27 | dnl Define it ourselves. Here we assume that the type 'size_t' is not wider | 25 | dnl Define it ourselves. Here we assume that the type 'size_t' is not wider |
28 | dnl than the type 'unsigned long'. | 26 | dnl than the type 'unsigned long'. Try hard to find a definition that can |
29 | dnl The _AC_COMPUTE_INT macro works up to LONG_MAX, since it uses 'expr', | 27 | dnl be used in a preprocessor #if, i.e. doesn't contain a cast. |
30 | dnl which is guaranteed to work from LONG_MIN to LONG_MAX. | 28 | AC_COMPUTE_INT([size_t_bits_minus_1], [sizeof (size_t) * CHAR_BIT - 1], |
31 | _AC_COMPUTE_INT([~(size_t)0 / 10], res_hi, | 29 | [#include <stddef.h> |
32 | [#include <stddef.h>], result=?) | 30 | #include <limits.h>], [size_t_bits_minus_1=]) |
33 | _AC_COMPUTE_INT([~(size_t)0 % 10], res_lo, | 31 | AC_COMPUTE_INT([fits_in_uint], [sizeof (size_t) <= sizeof (unsigned int)], |
34 | [#include <stddef.h>], result=?) | 32 | [#include <stddef.h>], [fits_in_uint=]) |
35 | _AC_COMPUTE_INT([sizeof (size_t) <= sizeof (unsigned int)], fits_in_uint, | 33 | if test -n "$size_t_bits_minus_1" && test -n "$fits_in_uint"; then |
36 | [#include <stddef.h>], result=?) | 34 | if test $fits_in_uint = 1; then |
37 | if test "$fits_in_uint" = 1; then | 35 | dnl Even though SIZE_MAX fits in an unsigned int, it must be of type |
38 | 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'. |
39 | dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'. | 37 | AC_COMPILE_IFELSE( |
40 | AC_TRY_COMPILE([#include <stddef.h> | 38 | [AC_LANG_PROGRAM( |
41 | extern size_t foo; | 39 | [[#include <stddef.h> |
42 | extern unsigned long foo; | 40 | extern size_t foo; |
43 | ], [], fits_in_uint=0) | 41 | extern unsigned long foo; |
44 | fi | 42 | ]], |
45 | if test -z "$result"; then | 43 | [[]])], |
46 | if test "$fits_in_uint" = 1; then | 44 | [fits_in_uint=0]) |
47 | result="$res_hi$res_lo"U | 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 << $size_t_bits_minus_1) - 1) * 2 + 1)" | ||
53 | fi | ||
48 | else | 54 | else |
49 | result="$res_hi$res_lo"UL | 55 | dnl Shouldn't happen, but who knows... |
56 | gl_cv_size_max='((size_t)~(size_t)0)' | ||
50 | fi | 57 | fi |
51 | else | ||
52 | dnl Shouldn't happen, but who knows... | ||
53 | result='~(size_t)0' | ||
54 | fi | 58 | fi |
55 | fi | 59 | ]) |
56 | AC_MSG_RESULT([$result]) | 60 | if test "$gl_cv_size_max" != yes; then |
57 | if test "$result" != yes; then | 61 | AC_DEFINE_UNQUOTED([SIZE_MAX], [$gl_cv_size_max], |
58 | AC_DEFINE_UNQUOTED([SIZE_MAX], [$result], | ||
59 | [Define as the maximum value of type 'size_t', if the system doesn't define it.]) | 62 | [Define as the maximum value of type 'size_t', if the system doesn't define it.]) |
60 | fi | 63 | fi |
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])]) | ||
61 | ]) | 79 | ]) |