1/*	$NetBSD: makecontext.c,v 1.2 2003/01/18 11:15:08 thorpej Exp $	*/
2
3/*-
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Klaus Klein.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#if defined(LIBC_SCCS) && !defined(lint)
34__RCSID("$NetBSD: makecontext.c,v 1.2 2003/01/18 11:15:08 thorpej Exp $");
35#endif
36
37#include <inttypes.h>
38#include <stddef.h>
39#include <ucontext.h>
40#include "extern.h"
41
42#include <stdarg.h>
43
44void
45makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
46{
47	__greg_t *gr = ucp->uc_mcontext.__gregs;
48	int i;
49	unsigned long *sp;
50	va_list ap;
51
52	sp = (unsigned long *)
53	    ((unsigned long)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
54	/* Make room for: rwindow, struct return pointer, argd, argx */
55	sp -= 8 + 8 + 1 + 6 + 1; /* CCFSZ, only in words */
56	/* CCFSZ provides space for up to 7 arguments, add more if necessary */
57	if (argc > 7)
58		sp -= argc - 7;
59	/* Align on double-word boundary. */
60	sp = (unsigned long *)((unsigned long)sp & ~0x7);
61
62	gr[_REG_O6] = (__greg_t)sp;
63	gr[_REG_PC] = (__greg_t)func;
64	gr[_REG_nPC] = (__greg_t)func + 4;
65	gr[_REG_O7] = (__greg_t)_resumecontext - 8;
66
67	va_start(ap, argc);
68	/* Pass up to 6 arguments in %o0..%o5. */
69	for (i = 0; i < argc && i < 6; i++)
70		gr[_REG_O0 + i] = va_arg(ap, unsigned long);
71	/* Pass any additional arguments on the stack. */
72	for (/* i = 6 */; i < argc; i++)
73		sp[8 + 8 + 1 + 6 + (i - 6)] = va_arg(ap, unsigned long);
74	va_end(ap);
75}
76