$NetBSD$

--- src/arch/netbsd/mcontext/mcontext.h.orig	2017-11-02 06:34:51.956237090 +0000
+++ src/arch/netbsd/mcontext/mcontext.h
@@ -0,0 +1,53 @@
+/* This code is taken from libtask library.
+ * Rip-off done by stsp for dosemu2 project.
+ * Original copyrights below. */
+
+/* Copyright (c) 2005-2006 Russ Cox, MIT; see COPYRIGHT */
+
+#ifndef MCONTEXT_H
+#define MCONTEXT_H
+
+#include <ucontext.h>
+
+typedef struct m_mcontext m_mcontext_t;
+typedef struct m_ucontext m_ucontext_t;
+
+#	if defined(__i386__)
+#		include "386-ucontext.h"
+#	elif defined(__x86_64__)
+#		include "amd64-ucontext.h"
+#	else
+#		error Unsupported arch
+#	endif
+
+struct m_ucontext {
+	/*
+	 * Keep the order of the first two fields. Also,
+	 * keep them the first two fields in the structure.
+	 * This way we can have a union with struct
+	 * sigcontext and ucontext_t. This allows us to
+	 * support them both at the same time.
+	 * note: the union is not defined, though.
+	 */
+	sigset_t	uc_sigmask;
+	m_mcontext_t	uc_mcontext;
+
+	struct __ucontext *uc_link;
+	stack_t		uc_stack;
+	int		__spare__[8];
+};
+
+extern	int		_getmcontext(m_mcontext_t*);
+extern	int		_setmcontext(const m_mcontext_t*);
+static inline int setmcontext(const struct m_ucontext *u)
+{
+	return _setmcontext(&u->uc_mcontext);
+}
+static inline int getmcontext(struct m_ucontext *u)
+{
+	return _getmcontext(&u->uc_mcontext);
+}
+extern	int		swapmcontext(m_ucontext_t*, const m_ucontext_t*);
+extern	void		makemcontext(m_ucontext_t*, void(*)(void), int, ...);
+
+#endif