2002-02-17 21:56:45 +00:00
|
|
|
<html>
|
|
|
|
|
<head>
|
|
|
|
|
<title>libsm : C Language Portability Macros</title>
|
|
|
|
|
</head>
|
|
|
|
|
<body>
|
|
|
|
|
|
|
|
|
|
<a href="index.html">Back to libsm overview</a>
|
|
|
|
|
|
|
|
|
|
<center>
|
|
|
|
|
<h1> libsm : C Language Portability Macros </h1>
|
2014-05-22 03:45:17 +00:00
|
|
|
<br> $Id: cdefs.html,v 1.2 2000-12-07 17:33:09 dmoen Exp $
|
2002-02-17 21:56:45 +00:00
|
|
|
</center>
|
|
|
|
|
|
|
|
|
|
<h2> Description </h2>
|
|
|
|
|
|
|
|
|
|
The header file <tt><sm/cdefs.h></tt>
|
|
|
|
|
defines portable interfaces to non-portable features
|
|
|
|
|
of various C compilers.
|
|
|
|
|
It also assists you in writing C header files that are compatible
|
|
|
|
|
with C++.
|
|
|
|
|
|
|
|
|
|
<dl>
|
|
|
|
|
<dt>
|
|
|
|
|
<tt> __P(parameterlist) </tt>
|
|
|
|
|
<dd>
|
|
|
|
|
This macro is used to write portable function prototypes.
|
|
|
|
|
For example,
|
|
|
|
|
|
|
|
|
|
<blockquote><pre>
|
|
|
|
|
int foo __P((int));
|
|
|
|
|
</pre></blockquote>
|
|
|
|
|
|
|
|
|
|
<dt>
|
|
|
|
|
<tt> __CONCAT(x,y) </tt>
|
|
|
|
|
<dd>
|
|
|
|
|
This macro concatenates two tokens x and y,
|
|
|
|
|
forming a single token xy.
|
|
|
|
|
Warning: make sure there is no white space around the arguments x and y.
|
|
|
|
|
<p>
|
|
|
|
|
|
|
|
|
|
<dt>
|
|
|
|
|
<tt> __STRING(x) </tt>
|
|
|
|
|
<dd>
|
|
|
|
|
This macro converts the token sequence x into a string literal.
|
|
|
|
|
<p>
|
|
|
|
|
|
|
|
|
|
<dt>
|
|
|
|
|
<tt> __BEGIN_DECLS, __END_DECLS </tt>
|
|
|
|
|
<dd>
|
|
|
|
|
These macros are used to write C header files that are compatible
|
|
|
|
|
with C++ compilers.
|
|
|
|
|
Put <tt>__BEGIN_DECLS</tt> before the first function or variable
|
|
|
|
|
declaration in your header file,
|
|
|
|
|
and put <tt>__END_DECLS</tt> after the last function or variable
|
|
|
|
|
declaration.
|
|
|
|
|
<p>
|
|
|
|
|
|
|
|
|
|
<dt>
|
|
|
|
|
<tt> const, signed, volatile </tt>
|
|
|
|
|
<dd>
|
|
|
|
|
For pre-ANSI C compilers, <tt>const</tt>, <tt>signed</tt>
|
|
|
|
|
and <tt>volatile</tt> are defined as empty macros.
|
|
|
|
|
This means you can use these keywords without introducing
|
|
|
|
|
portability problems.
|
|
|
|
|
<p>
|
|
|
|
|
|
|
|
|
|
<dt>
|
|
|
|
|
<tt> SM_DEAD(function_declaration) </tt>
|
|
|
|
|
<dd>
|
|
|
|
|
This macro modifies a prototype of a function
|
|
|
|
|
that does not return to its caller.
|
|
|
|
|
With some versions of gcc, this will result in slightly better code,
|
|
|
|
|
and can suppress some useless warnings produced by gcc -Wall.
|
|
|
|
|
For example,
|
|
|
|
|
|
|
|
|
|
<blockquote><pre>
|
|
|
|
|
SM_DEAD(void exit __P((int)));
|
|
|
|
|
</pre></blockquote>
|
|
|
|
|
|
|
|
|
|
<dt>
|
|
|
|
|
<tt> SM_UNUSED(variable_declaration) </tt>
|
|
|
|
|
<dd>
|
|
|
|
|
This macro modifies a definition of an unused
|
|
|
|
|
local variable, global variable or function parameter
|
|
|
|
|
in order to suppress compiler warnings.
|
|
|
|
|
Examples:
|
|
|
|
|
|
|
|
|
|
<blockquote><pre>
|
2014-05-22 03:45:17 +00:00
|
|
|
SM_UNUSED(static const char Id[]) = "@(#)$Id: cdefs.html,v 1.2 2000-12-07 17:33:09 dmoen Exp $";
|
2002-02-17 21:56:45 +00:00
|
|
|
void
|
|
|
|
|
foo(x)
|
|
|
|
|
SM_UNUSED(int x);
|
|
|
|
|
{
|
|
|
|
|
SM_UNUSED(int y) = 0;
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
void
|
|
|
|
|
bar(SM_UNUSED(int x))
|
|
|
|
|
{
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
</pre></blockquote>
|
|
|
|
|
|
|
|
|
|
</dl>
|
|
|
|
|
|
|
|
|
|
</body>
|
|
|
|
|
</html>
|
