1/* 2 * Copyright (c) 1993 Winning Strategies, Inc. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by Winning Strategies, Inc. 16 * 4. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31#include <machine/asm.h> 32__FBSDID("$FreeBSD$"); 33 34/* 35 * memcmp (void *b1, void *b2, size_t len) 36 * 37 * Written by: 38 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 39 */ 40 41ENTRY(memcmp) 42 pushl %edi 43 pushl %esi 44 movl 12(%esp),%edi 45 movl 16(%esp),%esi 46 cld /* set compare direction forward */ 47 48 movl 20(%esp),%ecx /* compare by words */ 49 shrl $2,%ecx 50 repe 51 cmpsl 52 jne L5 /* do we match so far? */ 53 54 movl 20(%esp),%ecx /* compare remainder by bytes */ 55 andl $3,%ecx 56 repe 57 cmpsb 58 jne L6 /* do we match? */ 59 60 xorl %eax,%eax /* we match, return zero */ 61 popl %esi 62 popl %edi 63 ret 64 65L5: movl $4,%ecx /* We know that one of the next */ 66 subl %ecx,%edi /* four pairs of bytes do not */ 67 subl %ecx,%esi /* match. */ 68 repe 69 cmpsb 70L6: movzbl -1(%edi),%eax /* Perform unsigned comparison */ 71 movzbl -1(%esi),%edx 72 subl %edx,%eax 73 popl %esi 74 popl %edi 75 ret 76