1/*	$NetBSD: bcmp.S,v 1.9 2009/12/14 01:07:42 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#define _LOCORE		/* XXX not really, just assembly-code source */
39#include <machine/endian.h>	/* LWLO/LWHI, SWLO/SWHI */
40
41#if defined(LIBC_SCCS) && !defined(lint)
42#if 0
43	ASMSTR("from: @(#)bcmp.s	8.1 (Berkeley) 6/4/93")
44#else
45	ASMSTR("$NetBSD: bcmp.S,v 1.9 2009/12/14 01:07:42 matt Exp $")
46#endif
47#endif /* LIBC_SCCS and not lint */
48
49#ifdef __ABICALLS__
50	.abicalls
51#endif
52
53/* bcmp(s1, s2, n) */
54
55
56LEAF(bcmp)
57	.set	noreorder
58	blt		a2, 16, small	# is it worth any trouble?
59	xor		v0, a0, a1	# compare low two bits of addresses
60	and		v0, v0, 3
61	PTR_SUBU	a3, zero, a1	# compute # bytes to word align address
62	bne		v0, zero, unaligned # not possible to align addresses
63	and		a3, a3, 3
64
65	beq		a3, zero, 1f
66	PTR_SUBU	a2, a2, a3	# subtract from remaining count
67	move		v0, v1		# init v0,v1 so unmodified bytes match
68	LWHI		v0, 0(a0)	# read 1, 2, or 3 bytes
69	LWHI		v1, 0(a1)
70	PTR_ADDU	a1, a1, a3
71	bne		v0, v1, nomatch
72	PTR_ADDU	a0, a0, a3
731:
74	and		a3, a2, ~3	# compute number of whole words left
75	PTR_SUBU	a2, a2, a3	#   which has to be >= (16-3) & ~3
76	PTR_ADDU	a3, a3, a0	# compute ending address
772:
78	lw		v0, 0(a0)	# compare words
79	lw		v1, 0(a1)
80	PTR_ADDU	a0, a0, 4
81	bne		v0, v1, nomatch
82	PTR_ADDU	a1, a1, 4
83	bne		a0, a3, 2b
84	nop
85	b		small		# finish remainder
86	nop
87unaligned:
88	beq		a3, zero, 2f
89	PTR_SUBU	a2, a2, a3	# subtract from remaining count
90	PTR_ADDU	a3, a3, a0	# compute ending address
911:
92	lbu		v0, 0(a0)	# compare bytes until a1 word aligned
93	lbu		v1, 0(a1)
94	PTR_ADDU	a0, a0, 1
95	bne		v0, v1, nomatch
96	PTR_ADDU	a1, a1, 1
97	bne		a0, a3, 1b
98	nop
992:
100	and		a3, a2, ~3	# compute number of whole words left
101	PTR_SUBU	a2, a2, a3	#   which has to be >= (16-3) & ~3
102	PTR_ADDU	a3, a3, a0	# compute ending address
1033:
104	LWHI		v0, 0(a0)	# compare words a0 unaligned, a1 aligned
105	LWLO		v0, 3(a0)
106	lw		v1, 0(a1)
107	PTR_ADDU	a0, a0, 4
108	bne		v0, v1, nomatch
109	PTR_ADDU	a1, a1, 4
110	bne		a0, a3, 3b
111	nop
112small:
113	ble		a2, zero, match
114	PTR_ADDU	a3, a2, a0		# compute ending address
1151:
116	lbu		v0, 0(a0)
117	lbu		v1, 0(a1)
118	PTR_ADDU	a0, a0, 1
119	bne		v0, v1, nomatch
120	PTR_ADDU	a1, a1, 1
121	bne		a0, a3, 1b
122	nop
123match:
124	j		ra
125	move		v0, zero
126nomatch:
127	j		ra
128	li		v0, 1
129	.set	reorder
130END(bcmp)
131