1 /* $NetBSD: memcmp.S,v 1.1 2005/12/20 19:28:49 christos Exp $ */
4 * Copyright 2003 Wasabi Systems, Inc.
7 * Written by Steve C. Woodford for Wasabi Systems, Inc.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
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. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed for the NetBSD Project by
20 * Wasabi Systems, Inc.
21 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
22 * or promote products derived from this software without specific prior
25 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
27 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC
29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35 * POSSIBILITY OF SUCH DAMAGE.
38 * Copyright (c) 2002 ARM Ltd
39 * All rights reserved.
41 * Redistribution and use in source and binary forms, with or without
42 * modification, are permitted provided that the following conditions
44 * 1. Redistributions of source code must retain the above copyright
45 * notice, this list of conditions and the following disclaimer.
46 * 2. Redistributions in binary form must reproduce the above copyright
47 * notice, this list of conditions and the following disclaimer in the
48 * documentation and/or other materials provided with the distribution.
49 * 3. The name of the company may not be used to endorse or promote
50 * products derived from this software without specific prior written
53 * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED
54 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
55 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
56 * IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
57 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
58 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
59 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
60 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
61 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
62 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
65 #include <machine/asm.h>
67 RCSID("$NetBSD: memcmp.S,v 1.1 2005/12/20 19:28:49 christos Exp $")
71 #if defined(_KERNEL) && !defined(_STANDALONE)
77 /* Are both addresses aligned the same way? */
80 RETc(eq) /* len == 0, or same addresses! */
83 bne .Lmemcmp_bytewise2 /* Badly aligned. Do it the slow way */
85 /* Word-align the addresses, if necessary */
88 add r3, r3, r3, lsl #1
89 addne pc, pc, r3, lsl #3
92 /* Compare up to 3 bytes */
100 /* Compare up to 2 bytes */
116 /* Compare 4 bytes at a time, if possible */
118 bcc .Lmemcmp_bytewise
119 .Lmemcmp_word_aligned:
124 beq .Lmemcmp_word_aligned
127 /* Correct for extra subtraction, and check if done */
129 cmpeq r0, #0x00 /* If done, did all bytes match? */
130 RETc(eq) /* Yup. Just return */
132 /* Re-do the final word byte-wise */
143 beq .Lmemcmp_bytewise2
147 #if defined(_KERNEL) && !defined(_STANDALONE)
149 * 6 byte compares are very common, thanks to the network stack.
150 * This code is hand-scheduled to reduce the number of stalls for
151 * load results. Everything else being equal, this will be ~32%
152 * faster than a byte-wise memcmp.
156 ldrb r3, [r1, #0x00] /* r3 = b2#0 */
157 ldrb r0, [ip, #0x00] /* r0 = b1#0 */
158 ldrb r2, [r1, #0x01] /* r2 = b2#1 */
159 subs r0, r0, r3 /* r0 = b1#0 - b2#0 */
160 ldreqb r3, [ip, #0x01] /* r3 = b1#1 */
161 RETc(ne) /* Return if mismatch on #0 */
162 subs r0, r3, r2 /* r0 = b1#1 - b2#1 */
163 ldreqb r3, [r1, #0x02] /* r3 = b2#2 */
164 ldreqb r0, [ip, #0x02] /* r0 = b1#2 */
165 RETc(ne) /* Return if mismatch on #1 */
166 ldrb r2, [r1, #0x03] /* r2 = b2#3 */
167 subs r0, r0, r3 /* r0 = b1#2 - b2#2 */
168 ldreqb r3, [ip, #0x03] /* r3 = b1#3 */
169 RETc(ne) /* Return if mismatch on #2 */
170 subs r0, r3, r2 /* r0 = b1#3 - b2#3 */
171 ldreqb r3, [r1, #0x04] /* r3 = b2#4 */
172 ldreqb r0, [ip, #0x04] /* r0 = b1#4 */
173 RETc(ne) /* Return if mismatch on #3 */
174 ldrb r2, [r1, #0x05] /* r2 = b2#5 */
175 subs r0, r0, r3 /* r0 = b1#4 - b2#4 */
176 ldreqb r3, [ip, #0x05] /* r3 = b1#5 */
177 RETc(ne) /* Return if mismatch on #4 */
178 sub r0, r3, r2 /* r0 = b1#5 - b2#5 */