minix/lib/libc/arch/vax/gen/makecontext.c

80 lines
2.7 KiB
C
Raw Normal View History

/* $NetBSD: makecontext.c,v 1.4 2012/03/22 17:32:22 christos Exp $ */
/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: makecontext.c,v 1.4 2012/03/22 17:32:22 christos Exp $");
#endif
#include <stddef.h>
#include <inttypes.h>
#include <ucontext.h>
#include "extern.h"
#include <stdarg.h>
void
makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
{
__greg_t *gr = ucp->uc_mcontext.__gregs;
va_list ap;
int *sp;
int i;
/* Compute and align stack pointer. */
sp = (int *)
(((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size) & ~0x3);
/*
* Allocate necessary stack space for arguments including arg count
* and call frame
*/
sp -= argc + 1 + 5;
va_start(ap, argc);
sp[5] = argc;
for (i = 1; argc > 0; argc--, i++)
sp[5 + i] = va_arg(ap, int);
va_end(ap);
sp[0] = 0; /* condition handler is null */
sp[1] = 0x20000000; /* make this a CALLS frame */
sp[2] = 0; /* saved argument pointer */
sp[3] = 0; /* saved frame pointer */
sp[4] = (int)(uintptr_t)_resumecontext+2;/* return via trampoline code */
gr[_REG_AP] = (__greg_t)(uintptr_t)(sp + 5);
gr[_REG_SP] = (__greg_t)(uintptr_t)sp;
gr[_REG_FP] = (__greg_t)(uintptr_t)sp;
gr[_REG_PC] = (__greg_t)(uintptr_t)func+2;
}