1/*	$NetBSD: bzero.S,v 1.10 2009/12/14 02:53:52 matt Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Ralph Campbell.
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
35#include <machine/asm.h>
36__FBSDID("$FreeBSD$");
37
38#if defined(LIBC_SCCS) && !defined(lint)
39#if 0
40	ASMSTR("from: @(#)bzero.s	8.1 (Berkeley) 6/4/93")
41#else
42	ASMSTR("$NetBSD: bzero.S,v 1.10 2009/12/14 02:53:52 matt Exp $")
43#endif
44#endif /* LIBC_SCCS and not lint */
45
46#define _LOCORE		/* XXX not really, just assembly-code source */
47#include <machine/endian.h>
48
49#ifdef __ABICALLS__
50	.abicalls
51#endif
52
53/* bzero(s1, n) */
54
55LEAF(bzero)
56	.set	noreorder
57	blt		a1, 3*SZREG, smallclr # small amount to clear?
58	PTR_SUBU	a3, zero, a0	# compute # bytes to word align address
59	and		a3, a3, SZREG-1
60	beq		a3, zero, 1f	# skip if word aligned
61	PTR_SUBU	a1, a1, a3	# subtract from remaining count
62	REG_SHI		zero, 0(a0)	# clear 1, 2, or 3 bytes to align
63	PTR_ADDU	a0, a0, a3
641:
65	and		v0, a1, SZREG-1	# compute number of words left
66	PTR_SUBU	a3, a1, v0
67	move		a1, v0
68	PTR_ADDU	a3, a3, a0	# compute ending address
692:
70	PTR_ADDU	a0, a0, SZREG	# clear words
71	bne		a0, a3, 2b	#  unrolling loop doesnt help
72	REG_S		zero, -SZREG(a0) # since we are limited by memory speed
73smallclr:
74	ble		a1, zero, 2f
75	PTR_ADDU	a3, a1, a0	# compute ending address
761:
77	PTR_ADDU	a0, a0, 1	# clear bytes
78	bne		a0, a3, 1b
79	sb		zero, -1(a0)
802:
81	j		ra
82	nop
83END(bzero)
84