sbrk.S revision 1.4 
1/*	$OpenBSD: sbrk.S,v 1.4 2005/08/07 16:40:15 espie Exp $ */
2/*-
3 * Copyright (c) 1991, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Ralph Campbell.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "SYS.h"
35
36	.globl	curbrk
37
38	.data
39curbrk:	PTR_VAL	_C_LABEL(end)
40	.text
41
42FRAMESZ= MKFSIZ(1,1)
43GPOFF= FRAMESZ-2*REGSZ
44
45LEAF(sbrk, FRAMESZ)
46	PTR_SUBU sp, FRAMESZ
47	SETUP_GP64(GPOFF, sbrk)
48	.set	reorder
49	PTR_L	v1, curbrk
50	li	v0, SYS_break
51	PTR_ADDU a0, a0, v1	# compute current break
52	syscall
53
54	bne	a3, zero, 1f
55	move	v0, v1		# return old val of curbrk from above
56	PTR_S	a0, curbrk	# save current val of curbrk from above
57	RESTORE_GP64
58	PTR_ADDU sp, FRAMESZ
59	j	ra
601:
61	LA	t9, _C_LABEL(cerror)
62	RESTORE_GP64
63	PTR_ADDU sp, FRAMESZ
64	jr	t9
65END(sbrk)
66