1/*	$NetBSD: alloca.S,v 1.7 2002/03/23 20:13:35 ross Exp $	*/
2
3/*-
4 * Copyright (c) 1990 The Regents of the University of California.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * William Jolitz.
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. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 *	from: @(#)alloca.s	5.2 (Berkeley) 5/14/90
35 */
36
37#include <machine/asm.h>
38#if defined(LIBC_SCCS)
39	RCSID("$NetBSD: alloca.S,v 1.7 2002/03/23 20:13:35 ross Exp $")
40#endif
41
42/* like alloc, but automatic free in return */
43
44ENTRY(alloca)
45	popl	%edx		/*  pop return addr */
46	popl	%eax		/*  pop amount to allocate */
47	movl	%esp,%ecx
48	addl	$3,%eax		/*  round up to next word */
49	andl	$-4,%eax
50	subl	%eax,%esp
51	movl	%esp,%eax	/* base of newly allocated space */
52	pushl	8(%ecx)		/* copy possible saved registers */
53	pushl	4(%ecx)
54	pushl	0(%ecx)
55	pushl	%eax		/* dummy to pop at callsite */
56	jmp	*%edx		/* "return" */
57