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 * bzero (void *b, size_t len) 36 * write len zero bytes to the string b. 37 * 38 * Written by: 39 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 40 */ 41 42ENTRY(bzero) 43 pushl %edi 44 pushl %ebx 45 movl 12(%esp),%edi 46 movl 16(%esp),%ecx 47 48 cld /* set fill direction forward */ 49 xorl %eax,%eax /* set fill data to 0 */ 50 51 /* 52 * if the string is too short, it's really not worth the overhead 53 * of aligning to word boundries, etc. So we jump to a plain 54 * unaligned set. 55 */ 56 cmpl $0x0f,%ecx 57 jle L1 58 59 movl %edi,%edx /* compute misalignment */ 60 negl %edx 61 andl $3,%edx 62 movl %ecx,%ebx 63 subl %edx,%ebx 64 65 movl %edx,%ecx /* zero until word aligned */ 66 rep 67 stosb 68 69 movl %ebx,%ecx /* zero by words */ 70 shrl $2,%ecx 71 rep 72 stosl 73 74 movl %ebx,%ecx 75 andl $3,%ecx /* zero remainder by bytes */ 76L1: rep 77 stosb 78 79 popl %ebx 80 popl %edi 81 ret 82