| 1 | # size_max.m4 serial 10 |
| 2 | dnl Copyright (C) 2003, 2005-2006, 2008-2013 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_CACHE_CHECK([for SIZE_MAX], [gl_cv_size_max], [ |
| 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 |
| 23 | ], [gl_cv_size_max=yes]) |
| 24 | if test -z "$gl_cv_size_max"; then |
| 25 | dnl Define it ourselves. Here we assume that the type 'size_t' is not wider |
| 26 | dnl than the type 'unsigned long'. Try hard to find a definition that can |
| 27 | dnl be used in a preprocessor #if, i.e. doesn't contain a cast. |
| 28 | AC_COMPUTE_INT([size_t_bits_minus_1], [sizeof (size_t) * CHAR_BIT - 1], |
| 29 | [#include <stddef.h> |
| 30 | #include <limits.h>], [size_t_bits_minus_1=]) |
| 31 | AC_COMPUTE_INT([fits_in_uint], [sizeof (size_t) <= sizeof (unsigned int)], |
| 32 | [#include <stddef.h>], [fits_in_uint=]) |
| 33 | if test -n "$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'. |
| 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]) |
| 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 |
| 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])]) |
| 79 | ]) |