memcmp.S revision 135682
1238106Sdes/* $NetBSD: memcmp.S,v 1.3 2003/10/14 07:51:45 scw Exp $ */ 2238106Sdes 3238106Sdes/* 4238106Sdes * Copyright 2003 Wasabi Systems, Inc. 5238106Sdes * All rights reserved. 6238106Sdes * 7238106Sdes * Written by Steve C. Woodford for Wasabi Systems, Inc. 8238106Sdes * 9238106Sdes * Redistribution and use in source and binary forms, with or without 10238106Sdes * modification, are permitted provided that the following conditions 11238106Sdes * are met: 12238106Sdes * 1. Redistributions of source code must retain the above copyright 13238106Sdes * notice, this list of conditions and the following disclaimer. 14238106Sdes * 2. Redistributions in binary form must reproduce the above copyright 15238106Sdes * notice, this list of conditions and the following disclaimer in the 16238106Sdes * documentation and/or other materials provided with the distribution. 17238106Sdes * 3. All advertising materials mentioning features or use of this software 18238106Sdes * must display the following acknowledgement: 19238106Sdes * This product includes software developed for the NetBSD Project by 20238106Sdes * Wasabi Systems, Inc. 21238106Sdes * 4. The name of Wasabi Systems, Inc. may not be used to endorse 22238106Sdes * or promote products derived from this software without specific prior 23238106Sdes * written permission. 24238106Sdes * 25238106Sdes * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND 26238106Sdes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27238106Sdes * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28238106Sdes * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC 29238106Sdes * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30238106Sdes * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31238106Sdes * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32238106Sdes * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33238106Sdes * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34238106Sdes * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35238106Sdes * POSSIBILITY OF SUCH DAMAGE. 36238106Sdes */ 37238106Sdes/* 38238106Sdes * Copyright (c) 2002 ARM Ltd 39238106Sdes * All rights reserved. 40238106Sdes * 41238106Sdes * Redistribution and use in source and binary forms, with or without 42238106Sdes * modification, are permitted provided that the following conditions 43238106Sdes * are met: 44238106Sdes * 1. Redistributions of source code must retain the above copyright 45238106Sdes * notice, this list of conditions and the following disclaimer. 46238106Sdes * 2. Redistributions in binary form must reproduce the above copyright 47238106Sdes * notice, this list of conditions and the following disclaimer in the 48238106Sdes * documentation and/or other materials provided with the distribution. 49238106Sdes * 3. The name of the company may not be used to endorse or promote 50238106Sdes * products derived from this software without specific prior written 51238106Sdes * permission. 52238106Sdes * 53238106Sdes * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED 54238106Sdes * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 55238106Sdes * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 56238106Sdes * IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 57238106Sdes * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 58238106Sdes * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 59238106Sdes * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 60238106Sdes * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 61238106Sdes * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 62238106Sdes * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 63238106Sdes */ 64238106Sdes 65238106Sdes#include <machine/asm.h> 66238106Sdes 67238106Sdes__FBSDID("$FreeBSD: head/lib/libc/arm/string/memcmp.S 135682 2004-09-23 23:10:56Z cognet $"); 68238106Sdes 69238106SdesENTRY(memcmp) 70238106Sdes mov ip, r0 71238106Sdes#if defined(_KERNEL) && !defined(_STANDALONE) 72238106Sdes cmp r2, #0x06 73238106Sdes beq .Lmemcmp_6bytes 74238106Sdes#endif 75238106Sdes mov r0, #0x00 76 77 /* Are both addresses aligned the same way? */ 78 cmp r2, #0x00 79 eornes r3, ip, r1 80 moveq pc, lr /* len == 0, or same addresses! */ 81 tst r3, #0x03 82 subne r2, r2, #0x01 83 bne .Lmemcmp_bytewise2 /* Badly aligned. Do it the slow way */ 84 85 /* Word-align the addresses, if necessary */ 86 sub r3, r1, #0x05 87 ands r3, r3, #0x03 88 add r3, r3, r3, lsl #1 89 addne pc, pc, r3, lsl #3 90 nop 91 92 /* Compare up to 3 bytes */ 93 ldrb r0, [ip], #0x01 94 ldrb r3, [r1], #0x01 95 subs r0, r0, r3 96 movne pc, lr 97 subs r2, r2, #0x01 98 moveq pc, lr 99 100 /* Compare up to 2 bytes */ 101 ldrb r0, [ip], #0x01 102 ldrb r3, [r1], #0x01 103 subs r0, r0, r3 104 movne pc, lr 105 subs r2, r2, #0x01 106 moveq pc, lr 107 108 /* Compare 1 byte */ 109 ldrb r0, [ip], #0x01 110 ldrb r3, [r1], #0x01 111 subs r0, r0, r3 112 movne pc, lr 113 subs r2, r2, #0x01 114 moveq pc, lr 115 116 /* Compare 4 bytes at a time, if possible */ 117 subs r2, r2, #0x04 118 bcc .Lmemcmp_bytewise 119.Lmemcmp_word_aligned: 120 ldr r0, [ip], #0x04 121 ldr r3, [r1], #0x04 122 subs r2, r2, #0x04 123 cmpcs r0, r3 124 beq .Lmemcmp_word_aligned 125 sub r0, r0, r3 126 127 /* Correct for extra subtraction, and check if done */ 128 adds r2, r2, #0x04 129 cmpeq r0, #0x00 /* If done, did all bytes match? */ 130 moveq pc, lr /* Yup. Just return */ 131 132 /* Re-do the final word byte-wise */ 133 sub ip, ip, #0x04 134 sub r1, r1, #0x04 135 136.Lmemcmp_bytewise: 137 add r2, r2, #0x03 138.Lmemcmp_bytewise2: 139 ldrb r0, [ip], #0x01 140 ldrb r3, [r1], #0x01 141 subs r2, r2, #0x01 142 cmpcs r0, r3 143 beq .Lmemcmp_bytewise2 144 sub r0, r0, r3 145 mov pc, lr 146 147#if defined(_KERNEL) && !defined(_STANDALONE) 148 /* 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. 153 */ 154 .align 5 155.Lmemcmp_6bytes: 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 movne pc, lr /* 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 movne pc, lr /* 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 movne pc, lr /* 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 movne pc, lr /* 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 movne pc, lr /* Return if mismatch on #4 */ 178 sub r0, r3, r2 /* r0 = b1#5 - b2#5 */ 179 mov pc, lr 180#endif 181