/* $NetBSD: memcmp.S,v 1.3 2003/10/14 07:51:45 scw Exp $ */ /* * Copyright 2003 Wasabi Systems, Inc. * All rights reserved. * * Written by Steve C. Woodford for Wasabi Systems, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed for the NetBSD Project by * Wasabi Systems, Inc. * 4. The name of Wasabi Systems, Inc. may not be used to endorse * or promote products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 2002 ARM Ltd * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the company may not be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include <machine/asm.h> .syntax unified ENTRY(memcmp) mov ip, r0 #if defined(_KERNEL) && !defined(_STANDALONE) cmp r2, #0x06 beq .Lmemcmp_6bytes #endif mov r0, #0x00 /* Are both addresses aligned the same way? */ cmp r2, #0x00 eorsne r3, ip, r1 RETeq /* len == 0, or same addresses! */ tst r3, #0x03 subne r2, r2, #0x01 bne .Lmemcmp_bytewise2 /* Badly aligned. Do it the slow way */ /* Word-align the addresses, if necessary */ sub r3, r1, #0x05 ands r3, r3, #0x03 add r3, r3, r3, lsl #1 addne pc, pc, r3, lsl #3 nop /* Compare up to 3 bytes */ ldrb r0, [ip], #0x01 ldrb r3, [r1], #0x01 subs r0, r0, r3 RETne subs r2, r2, #0x01 RETeq /* Compare up to 2 bytes */ ldrb r0, [ip], #0x01 ldrb r3, [r1], #0x01 subs r0, r0, r3 RETne subs r2, r2, #0x01 RETeq /* Compare 1 byte */ ldrb r0, [ip], #0x01 ldrb r3, [r1], #0x01 subs r0, r0, r3 RETne subs r2, r2, #0x01 RETeq /* Compare 4 bytes at a time, if possible */ subs r2, r2, #0x04 bcc .Lmemcmp_bytewise .Lmemcmp_word_aligned: ldr r0, [ip], #0x04 ldr r3, [r1], #0x04 subs r2, r2, #0x04 cmpcs r0, r3 beq .Lmemcmp_word_aligned sub r0, r0, r3 /* Correct for extra subtraction, and check if done */ adds r2, r2, #0x04 cmpeq r0, #0x00 /* If done, did all bytes match? */ RETeq /* Yup. Just return */ /* Re-do the final word byte-wise */ sub ip, ip, #0x04 sub r1, r1, #0x04 .Lmemcmp_bytewise: add r2, r2, #0x03 .Lmemcmp_bytewise2: ldrb r0, [ip], #0x01 ldrb r3, [r1], #0x01 subs r2, r2, #0x01 cmpcs r0, r3 beq .Lmemcmp_bytewise2 sub r0, r0, r3 RET #if defined(_KERNEL) && !defined(_STANDALONE) /* * 6 byte compares are very common, thanks to the network stack. * This code is hand-scheduled to reduce the number of stalls for * load results. Everything else being equal, this will be ~32% * faster than a byte-wise memcmp. */ .align 5 .Lmemcmp_6bytes: ldrb r3, [r1, #0x00] /* r3 = b2#0 */ ldrb r0, [ip, #0x00] /* r0 = b1#0 */ ldrb r2, [r1, #0x01] /* r2 = b2#1 */ subs r0, r0, r3 /* r0 = b1#0 - b2#0 */ ldreqb r3, [ip, #0x01] /* r3 = b1#1 */ RETne /* Return if mismatch on #0 */ subs r0, r3, r2 /* r0 = b1#1 - b2#1 */ ldreqb r3, [r1, #0x02] /* r3 = b2#2 */ ldreqb r0, [ip, #0x02] /* r0 = b1#2 */ RETne /* Return if mismatch on #1 */ ldrb r2, [r1, #0x03] /* r2 = b2#3 */ subs r0, r0, r3 /* r0 = b1#2 - b2#2 */ ldreqb r3, [ip, #0x03] /* r3 = b1#3 */ RETne /* Return if mismatch on #2 */ subs r0, r3, r2 /* r0 = b1#3 - b2#3 */ ldreqb r3, [r1, #0x04] /* r3 = b2#4 */ ldreqb r0, [ip, #0x04] /* r0 = b1#4 */ RETne /* Return if mismatch on #3 */ ldrb r2, [r1, #0x05] /* r2 = b2#5 */ subs r0, r0, r3 /* r0 = b1#4 - b2#4 */ ldreqb r3, [ip, #0x05] /* r3 = b1#5 */ RETne /* Return if mismatch on #4 */ sub r0, r3, r2 /* r0 = b1#5 - b2#5 */ RET #endif END(memcmp) .section .note.GNU-stack,"",%progbits
