62 lines
2.1 KiB
Text
62 lines
2.1 KiB
Text
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# size_max.m4 serial 2
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dnl Copyright (C) 2003 Free Software Foundation, Inc.
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dnl This file is free software, distributed under the terms of the GNU
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dnl General Public License. As a special exception to the GNU General
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dnl Public License, this file may be distributed as part of a program
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dnl that contains a configuration script generated by Autoconf, under
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dnl the same distribution terms as the rest of that program.
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dnl From Bruno Haible.
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AC_DEFUN([gl_SIZE_MAX],
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[
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AC_CHECK_HEADERS(stdint.h)
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dnl First test whether the system already has SIZE_MAX.
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AC_MSG_CHECKING([for SIZE_MAX])
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result=
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AC_EGREP_CPP([Found it], [
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#include <limits.h>
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#if HAVE_STDINT_H
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#include <stdint.h>
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#endif
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#ifdef SIZE_MAX
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Found it
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#endif
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], result=yes)
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if test -z "$result"; then
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dnl Define it ourselves. Here we assume that the type 'size_t' is not wider
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dnl than the type 'unsigned long'.
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dnl The _AC_COMPUTE_INT macro works up to LONG_MAX, since it uses 'expr',
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dnl which is guaranteed to work from LONG_MIN to LONG_MAX.
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_AC_COMPUTE_INT([~(size_t)0 / 10], res_hi,
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[#include <stddef.h>], result=?)
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_AC_COMPUTE_INT([~(size_t)0 % 10], res_lo,
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[#include <stddef.h>], result=?)
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_AC_COMPUTE_INT([sizeof (size_t) <= sizeof (unsigned int)], fits_in_uint,
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[#include <stddef.h>], result=?)
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if test "$fits_in_uint" = 1; then
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dnl Even though SIZE_MAX fits in an unsigned int, it must be of type
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dnl 'unsigned long' if the type 'size_t' is the same as 'unsigned long'.
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AC_TRY_COMPILE([#include <stddef.h>
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extern size_t foo;
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extern unsigned long foo;
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], [], fits_in_uint=0)
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fi
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if test -z "$result"; then
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if test "$fits_in_uint" = 1; then
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result="$res_hi$res_lo"U
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else
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result="$res_hi$res_lo"UL
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fi
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else
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dnl Shouldn't happen, but who knows...
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result='~(size_t)0'
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fi
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fi
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AC_MSG_RESULT([$result])
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if test "$result" != yes; then
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AC_DEFINE_UNQUOTED([SIZE_MAX], [$result],
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[Define as the maximum value of type 'size_t', if the system doesn't define it.])
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fi
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])
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