memcmp.S revision 129202
1129202Scognet/* $NetBSD: memcmp.S,v 1.3 2003/10/14 07:51:45 scw Exp $ */ 2129202Scognet 3129202Scognet/* 4129202Scognet * Copyright 2003 Wasabi Systems, Inc. 5129202Scognet * All rights reserved. 6129202Scognet * 7129202Scognet * Written by Steve C. Woodford for Wasabi Systems, Inc. 8129202Scognet * 9129202Scognet * Redistribution and use in source and binary forms, with or without 10129202Scognet * modification, are permitted provided that the following conditions 11129202Scognet * are met: 12129202Scognet * 1. Redistributions of source code must retain the above copyright 13129202Scognet * notice, this list of conditions and the following disclaimer. 14129202Scognet * 2. Redistributions in binary form must reproduce the above copyright 15129202Scognet * notice, this list of conditions and the following disclaimer in the 16129202Scognet * documentation and/or other materials provided with the distribution. 17129202Scognet * 3. All advertising materials mentioning features or use of this software 18129202Scognet * must display the following acknowledgement: 19129202Scognet * This product includes software developed for the NetBSD Project by 20129202Scognet * Wasabi Systems, Inc. 21129202Scognet * 4. The name of Wasabi Systems, Inc. may not be used to endorse 22129202Scognet * or promote products derived from this software without specific prior 23129202Scognet * written permission. 24129202Scognet * 25129202Scognet * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND 26129202Scognet * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27129202Scognet * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28129202Scognet * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC 29129202Scognet * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30129202Scognet * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31129202Scognet * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32129202Scognet * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33129202Scognet * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34129202Scognet * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35129202Scognet * POSSIBILITY OF SUCH DAMAGE. 36129202Scognet */ 37129202Scognet/* 38129202Scognet * Copyright (c) 2002 ARM Ltd 39129202Scognet * All rights reserved. 40129202Scognet * 41129202Scognet * Redistribution and use in source and binary forms, with or without 42129202Scognet * modification, are permitted provided that the following conditions 43129202Scognet * are met: 44129202Scognet * 1. Redistributions of source code must retain the above copyright 45129202Scognet * notice, this list of conditions and the following disclaimer. 46129202Scognet * 2. Redistributions in binary form must reproduce the above copyright 47129202Scognet * notice, this list of conditions and the following disclaimer in the 48129202Scognet * documentation and/or other materials provided with the distribution. 49129202Scognet * 3. The name of the company may not be used to endorse or promote 50129202Scognet * products derived from this software without specific prior written 51129202Scognet * permission. 52129202Scognet * 53129202Scognet * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED 54129202Scognet * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 55129202Scognet * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 56129202Scognet * IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 57129202Scognet * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 58129202Scognet * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 59129202Scognet * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 60129202Scognet * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 61129202Scognet * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 62129202Scognet * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 63129202Scognet */ 64129202Scognet 65129202Scognet#include <machine/asm.h> 66129202Scognet 67129202Scognet__FBSDID("$FreeBSD: head/lib/libc/arm/string/memcmp.S 129202 2004-05-14 12:04:31Z cognet $"); 68129202Scognet 69129202ScognetENTRY(memcmp) 70129202Scognet mov ip, r0 71129202Scognet#if defined(_KERNEL) && !defined(_STANDALONE) 72129202Scognet cmp r2, #0x06 73129202Scognet beq .Lmemcmp_6bytes 74129202Scognet#endif 75129202Scognet mov r0, #0x00 76129202Scognet 77129202Scognet /* Are both addresses aligned the same way? */ 78129202Scognet cmp r2, #0x00 79129202Scognet eornes r3, ip, r1 80129202Scognet moveq pc, lr /* len == 0, or same addresses! */ 81129202Scognet tst r3, #0x03 82129202Scognet subne r2, r2, #0x01 83129202Scognet bne .Lmemcmp_bytewise2 /* Badly aligned. Do it the slow way */ 84129202Scognet 85129202Scognet /* Word-align the addresses, if necessary */ 86129202Scognet and r3, r1, #0x03 87129202Scognet rsbs r3, r3, #0x03 88129202Scognet add r3, r3, r3, lsl #1 89129202Scognet addne pc, pc, r3, lsl #3 90129202Scognet nop 91129202Scognet 92129202Scognet /* Compare up to 3 bytes */ 93129202Scognet ldrb r0, [ip], #0x01 94129202Scognet ldrb r3, [r1], #0x01 95129202Scognet subs r0, r0, r3 96129202Scognet movne pc, lr 97129202Scognet subs r2, r2, #0x01 98129202Scognet moveq pc, lr 99129202Scognet 100129202Scognet /* Compare up to 2 bytes */ 101129202Scognet ldrb r0, [ip], #0x01 102129202Scognet ldrb r3, [r1], #0x01 103129202Scognet subs r0, r0, r3 104129202Scognet movne pc, lr 105129202Scognet subs r2, r2, #0x01 106129202Scognet moveq pc, lr 107129202Scognet 108129202Scognet /* Compare 1 byte */ 109129202Scognet ldrb r0, [ip], #0x01 110129202Scognet ldrb r3, [r1], #0x01 111129202Scognet subs r0, r0, r3 112129202Scognet movne pc, lr 113129202Scognet subs r2, r2, #0x01 114129202Scognet moveq pc, lr 115129202Scognet 116129202Scognet /* Compare 4 bytes at a time, if possible */ 117129202Scognet subs r2, r2, #0x04 118129202Scognet bcc .Lmemcmp_bytewise 119129202Scognet.Lmemcmp_word_aligned: 120129202Scognet ldr r0, [ip], #0x04 121129202Scognet ldr r3, [r1], #0x04 122129202Scognet subs r2, r2, #0x04 123129202Scognet cmpcs r0, r3 124129202Scognet beq .Lmemcmp_word_aligned 125129202Scognet sub r0, r0, r3 126129202Scognet 127129202Scognet /* Correct for extra subtraction, and check if done */ 128129202Scognet adds r2, r2, #0x04 129129202Scognet cmpeq r0, #0x00 /* If done, did all bytes match? */ 130129202Scognet moveq pc, lr /* Yup. Just return */ 131129202Scognet 132129202Scognet /* Re-do the final word byte-wise */ 133129202Scognet sub ip, ip, #0x04 134129202Scognet sub r1, r1, #0x04 135129202Scognet 136129202Scognet.Lmemcmp_bytewise: 137129202Scognet add r2, r2, #0x03 138129202Scognet.Lmemcmp_bytewise2: 139129202Scognet ldrb r0, [ip], #0x01 140129202Scognet ldrb r3, [r1], #0x01 141129202Scognet subs r2, r2, #0x01 142129202Scognet cmpcs r0, r3 143129202Scognet beq .Lmemcmp_bytewise2 144129202Scognet sub r0, r0, r3 145129202Scognet mov pc, lr 146129202Scognet 147129202Scognet#if defined(_KERNEL) && !defined(_STANDALONE) 148129202Scognet /* 149129202Scognet * 6 byte compares are very common, thanks to the network stack. 150129202Scognet * This code is hand-scheduled to reduce the number of stalls for 151129202Scognet * load results. Everything else being equal, this will be ~32% 152129202Scognet * faster than a byte-wise memcmp. 153129202Scognet */ 154129202Scognet .align 5 155129202Scognet.Lmemcmp_6bytes: 156129202Scognet ldrb r3, [r1, #0x00] /* r3 = b2#0 */ 157129202Scognet ldrb r0, [ip, #0x00] /* r0 = b1#0 */ 158129202Scognet ldrb r2, [r1, #0x01] /* r2 = b2#1 */ 159129202Scognet subs r0, r0, r3 /* r0 = b1#0 - b2#0 */ 160129202Scognet ldreqb r3, [ip, #0x01] /* r3 = b1#1 */ 161129202Scognet movne pc, lr /* Return if mismatch on #0 */ 162129202Scognet subs r0, r3, r2 /* r0 = b1#1 - b2#1 */ 163129202Scognet ldreqb r3, [r1, #0x02] /* r3 = b2#2 */ 164129202Scognet ldreqb r0, [ip, #0x02] /* r0 = b1#2 */ 165129202Scognet movne pc, lr /* Return if mismatch on #1 */ 166129202Scognet ldrb r2, [r1, #0x03] /* r2 = b2#3 */ 167129202Scognet subs r0, r0, r3 /* r0 = b1#2 - b2#2 */ 168129202Scognet ldreqb r3, [ip, #0x03] /* r3 = b1#3 */ 169129202Scognet movne pc, lr /* Return if mismatch on #2 */ 170129202Scognet subs r0, r3, r2 /* r0 = b1#3 - b2#3 */ 171129202Scognet ldreqb r3, [r1, #0x04] /* r3 = b2#4 */ 172129202Scognet ldreqb r0, [ip, #0x04] /* r0 = b1#4 */ 173129202Scognet movne pc, lr /* Return if mismatch on #3 */ 174129202Scognet ldrb r2, [r1, #0x05] /* r2 = b2#5 */ 175129202Scognet subs r0, r0, r3 /* r0 = b1#4 - b2#4 */ 176129202Scognet ldreqb r3, [ip, #0x05] /* r3 = b1#5 */ 177129202Scognet movne pc, lr /* Return if mismatch on #4 */ 178129202Scognet sub r0, r3, r2 /* r0 = b1#5 - b2#5 */ 179129202Scognet mov pc, lr 180129202Scognet#endif 181