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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
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<head>
<title>
Autoconf Macro: vl_check_sign
</title>
<link rel="stylesheet" type="text/css" href="ac-archive.css">
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<body>
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<tbody>
<tr>
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<a href="http://autoconf-archive.cryp.to/vl_check_sign.m4">Download M4
Source</a>
</td>
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<a href="macros-by-category.html">Macro Index Page</a>
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<hr>
<h1>
vl_check_sign
</h1>
<h2>
Synopsis
</h2>
<p class="indent" style="white-space:nowrap;">
<code>VL_CHECK_SIGN (TYPE, [ACTION-IF-SIGNED], [ACTION-IF-UNSIGNED],
[INCLUDES])</code>
</p>
<h2>
Description
</h2>
<div class="indent">
<p>
Checks whether TYPE is signed or not. If no INCLUDES are specified, the
default includes are used. If ACTION-IF-SIGNED is given, it is additional
shell code to execute when the type is signed. If ACTION-IF-UNSIGNED is
given, it is executed when the type is unsigned.
</p>
<p>
This macro assumes that the type exists. Therefore the existence of the
type should be checked before calling this macro. For example:
</p>
<pre>
AC_CHECK_HEADERS([wchar.h])
AC_CHECK_TYPE([wchar_t],,[ AC_MSG_ERROR([Type wchar_t not found.]) ])
VL_CHECK_SIGN([wchar_t],
[ AC_DEFINE(WCHAR_T_SIGNED, 1, [Define if wchar_t is signed]) ],
[ AC_DEFINE(WCHAR_T_UNSIGNED, 1, [Define if wchar_t is unsigned]) ], [
#ifdef HAVE_WCHAR_H
#include <wchar.h>
#endif
])
</pre>
</div>
<h2>
Author
</h2>
<p class="indent">
Ville Laurikari <vl@iki.fi>
</p>
<h2>
Last Modified
</h2>
<p class="indent">
2002-04-04
</p>
<h2>
M4 Source Code
</h2>
<div class="indent">
<pre class="m4source">
AC_DEFUN([VL_CHECK_SIGN], [
typename=`echo $1 | sed "s/@<:@^a-zA-Z0-9_@:>@/_/g"`
AC_CACHE_CHECK([whether $1 is signed], vl_cv_decl_${typename}_signed, [
AC_TRY_COMPILE([$4],
[ int foo @<:@ 1 - 2 * !((($1) -1) < 0) @:>@ ],
[ eval "vl_cv_decl_${typename}_signed=\"yes\"" ],
[ eval "vl_cv_decl_${typename}_signed=\"no\"" ])])
symbolname=`echo $1 | sed "s/@<:@^a-zA-Z0-9_@:>@/_/g" | tr "a-z" "A-Z"`
if eval "test \"\${vl_cv_decl_${typename}_signed}\" = \"yes\""; then
$2
elif eval "test \"\${vl_cv_decl_${typename}_signed}\" = \"no\""; then
$3
fi
])dnl
</pre>
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