makecontext.c revision 1.2 
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 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *        This product includes software developed by the NetBSD
21 *        Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 *    contributors may be used to endorse or promote products derived
24 *    from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39#include <sys/cdefs.h>
40#if defined(LIBC_SCCS) && !defined(lint)
41__RCSID("$NetBSD: makecontext.c,v 1.2 2003/01/18 11:15:08 thorpej Exp $");
42#endif
43
44#include <inttypes.h>
45#include <stddef.h>
46#include <ucontext.h>
47#include "extern.h"
48
49#include <stdarg.h>
50
51void
52makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
53{
54	__greg_t *gr = ucp->uc_mcontext.__gregs;
55	int i;
56	unsigned long *sp;
57	va_list ap;
58
59	sp = (unsigned long *)
60	    ((unsigned long)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
61	/* Make room for: rwindow, struct return pointer, argd, argx */
62	sp -= 8 + 8 + 1 + 6 + 1; /* CCFSZ, only in words */
63	/* CCFSZ provides space for up to 7 arguments, add more if necessary */
64	if (argc > 7)
65		sp -= argc - 7;
66	/* Align on double-word boundary. */
67	sp = (unsigned long *)((unsigned long)sp & ~0x7);
68
69	gr[_REG_O6] = (__greg_t)sp;
70	gr[_REG_PC] = (__greg_t)func;
71	gr[_REG_nPC] = (__greg_t)func + 4;
72	gr[_REG_O7] = (__greg_t)_resumecontext - 8;
73
74	va_start(ap, argc);
75	/* Pass up to 6 arguments in %o0..%o5. */
76	for (i = 0; i < argc && i < 6; i++)
77		gr[_REG_O0 + i] = va_arg(ap, unsigned long);
78	/* Pass any additional arguments on the stack. */
79	for (/* i = 6 */; i < argc; i++)
80		sp[8 + 8 + 1 + 6 + (i - 6)] = va_arg(ap, unsigned long);
81	va_end(ap);
82}
83