+/* XSUB.h
+ *
+ * Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
+ * 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others
+ *
+ * You may distribute under the terms of either the GNU General Public
+ * License or the Artistic License, as specified in the README file.
+ *
+ */
+
+#ifndef _INC_PERL_XSUB_H
+#define _INC_PERL_XSUB_H 1
+
+/* first, some documentation for xsubpp-generated items */
+
+/*
+=head1 Variables created by C<xsubpp> and C<xsubpp> internal functions
+
+=for apidoc Amn|char*|CLASS
+Variable which is setup by C<xsubpp> to indicate the
+class name for a C++ XS constructor. This is always a C<char*>. See C<THIS>.
+
+=for apidoc Amn|(whatever)|RETVAL
+Variable which is setup by C<xsubpp> to hold the return value for an
+XSUB. This is always the proper type for the XSUB. See
+L<perlxs/"The RETVAL Variable">.
+
+=for apidoc Amn|(whatever)|THIS
+Variable which is setup by C<xsubpp> to designate the object in a C++
+XSUB. This is always the proper type for the C++ object. See C<CLASS> and
+L<perlxs/"Using XS With C++">.
+
+=for apidoc Amn|I32|ax
+Variable which is setup by C<xsubpp> to indicate the stack base offset,
+used by the C<ST>, C<XSprePUSH> and C<XSRETURN> macros. The C<dMARK> macro
+must be called prior to setup the C<MARK> variable.
+
+=for apidoc Amn|I32|items
+Variable which is setup by C<xsubpp> to indicate the number of
+items on the stack. See L<perlxs/"Variable-length Parameter Lists">.
+
+=for apidoc Amn|I32|ix
+Variable which is setup by C<xsubpp> to indicate which of an
+XSUB's aliases was used to invoke it. See L<perlxs/"The ALIAS: Keyword">.
+
+=for apidoc Am|SV*|ST|int ix
+Used to access elements on the XSUB's stack.
+
+=for apidoc AmU||XS
+Macro to declare an XSUB and its C parameter list. This is handled by
+C<xsubpp>.
+
+=for apidoc Ams||dAX
+Sets up the C<ax> variable.
+This is usually handled automatically by C<xsubpp> by calling C<dXSARGS>.
+
+=for apidoc Ams||dAXMARK
+Sets up the C<ax> variable and stack marker variable C<mark>.
+This is usually handled automatically by C<xsubpp> by calling C<dXSARGS>.
+
+=for apidoc Ams||dITEMS
+Sets up the C<items> variable.
+This is usually handled automatically by C<xsubpp> by calling C<dXSARGS>.
+
+=for apidoc Ams||dXSARGS
+Sets up stack and mark pointers for an XSUB, calling dSP and dMARK.
+Sets up the C<ax> and C<items> variables by calling C<dAX> and C<dITEMS>.
+This is usually handled automatically by C<xsubpp>.
+
+=for apidoc Ams||dXSI32
+Sets up the C<ix> variable for an XSUB which has aliases. This is usually
+handled automatically by C<xsubpp>.
+
+=for apidoc Ams||dUNDERBAR
+Sets up the C<padoff_du> variable for an XSUB that wishes to use
+C<UNDERBAR>.
+
+=for apidoc AmU||UNDERBAR
+The SV* corresponding to the $_ variable. Works even if there
+is a lexical $_ in scope.
+
+=cut
+*/
+
+#ifndef PERL_UNUSED_ARG
+# if defined(lint) && defined(S_SPLINT_S) /* www.splint.org */
+# include <note.h>
+# define PERL_UNUSED_ARG(x) NOTE(ARGUNUSED(x))
+# else
+# define PERL_UNUSED_ARG(x) ((void)x)
+# endif
+#endif
+#ifndef PERL_UNUSED_VAR
+# define PERL_UNUSED_VAR(x) ((void)x)
+#endif
+