Mercurial > hg > octave-lojdl > gnulib-hg
changeset 4860:4203fbdbf596
Macro for determining SIZE_MAX.
author | Bruno Haible <bruno@clisp.org> |
---|---|
date | Tue, 11 Nov 2003 11:56:48 +0000 |
parents | a7a0af3a9e13 |
children | 1d3dc83fb7a5 |
files | m4/size_max.m4 |
diffstat | 1 files changed, 61 insertions(+), 0 deletions(-) [+] |
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new file mode 100644 --- /dev/null +++ b/m4/size_max.m4 @@ -0,0 +1,61 @@ +# size_max.m4 serial 1 +dnl Copyright (C) 2003 Free Software Foundation, Inc. +dnl This file is free software, distributed under the terms of the GNU +dnl General Public License. As a special exception to the GNU General +dnl Public License, this file may be distributed as part of a program +dnl that contains a configuration script generated by Autoconf, under +dnl the same distribution terms as the rest of that program. + +dnl From Bruno Haible. + +AC_DEFUN([gl_SIZE_MAX], +[ + AC_CHECK_HEADERS_ONCE(stdint.h) + dnl First test whether the system already has SIZE_MAX. + AC_MSG_CHECKING([for SIZE_MAX]) + result= + AC_EGREP_CPP([Found it], [ +#include <limits.h> +#if HAVE_STDINT_H +#include <stdint.h> +#endif +#ifdef SIZE_MAX +Found it +#endif +], result=yes) + if test -z "$result"; then + dnl Define it ourselves. Here we assume that the type 'size_t' is not wider + dnl than the type 'unsigned long'. + dnl The _AC_COMPUTE_INT macro works up to LONG_MAX, since it uses 'expr', + dnl which is guaranteed to work from LONG_MIN to LONG_MAX. + _AC_COMPUTE_INT([~(size_t)0 / 10], res_hi, + [#include <stddef.h>], result=?) + _AC_COMPUTE_INT([~(size_t)0 % 10], res_lo, + [#include <stddef.h>], result=?) + _AC_COMPUTE_INT([sizeof (size_t) <= sizeof (unsigned int)], fits_in_uint, + [#include <stddef.h>], result=?) + if test "$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 + if test -z "$result"; then + if test "$fits_in_uint" = 1; then + result="$res_hi$res_lo"U + else + result="$res_hi$res_lo"UL + fi + else + dnl Shouldn't happen, but who knows... + result='~(size_t)0' + fi + fi + AC_MSG_RESULT([$result]) + if test "$result" != yes; then + AC_DEFINE_UNQUOTED([SIZE_MAX], [$result], + [Define as the maximum value of type 'size_t', if the system doesn't define it.]) + fi +])