bzero.S revision 1.6
1 1.1 cgd /* 2 1.1 cgd * Copyright (c) 1993 Winning Strategies, Inc. 3 1.1 cgd * All rights reserved. 4 1.1 cgd * 5 1.1 cgd * Redistribution and use in source and binary forms, with or without 6 1.1 cgd * modification, are permitted provided that the following conditions 7 1.1 cgd * are met: 8 1.1 cgd * 1. Redistributions of source code must retain the above copyright 9 1.1 cgd * notice, this list of conditions and the following disclaimer. 10 1.1 cgd * 2. Redistributions in binary form must reproduce the above copyright 11 1.1 cgd * notice, this list of conditions and the following disclaimer in the 12 1.1 cgd * documentation and/or other materials provided with the distribution. 13 1.1 cgd * 3. All advertising materials mentioning features or use of this software 14 1.1 cgd * must display the following acknowledgement: 15 1.1 cgd * This product includes software developed by Winning Strategies, Inc. 16 1.1 cgd * 4. The name of the author may not be used to endorse or promote products 17 1.4 jtc * derived from this software without specific prior written permission 18 1.1 cgd * 19 1.1 cgd * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 1.1 cgd * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 1.1 cgd * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 1.1 cgd * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 1.1 cgd * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 1.1 cgd * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 1.1 cgd * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 1.1 cgd * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 1.1 cgd * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 1.1 cgd * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 1.1 cgd * 30 1.6 mycroft * $Id: bzero.S,v 1.6 1995/02/05 14:58:44 mycroft Exp $ 31 1.1 cgd */ 32 1.1 cgd 33 1.5 jtc #include <machine/asm.h> 34 1.5 jtc 35 1.2 jtc #if defined(LIBC_SCCS) 36 1.6 mycroft RCSID("$Id: bzero.S,v 1.6 1995/02/05 14:58:44 mycroft Exp $") 37 1.2 jtc #endif 38 1.1 cgd 39 1.1 cgd /* 40 1.1 cgd * bzero (void *b, size_t len) 41 1.1 cgd * write len zero bytes to the string b. 42 1.1 cgd * 43 1.1 cgd * Written by: 44 1.1 cgd * J.T. Conklin (jtc (at) wimsey.com), Winning Strategies, Inc. 45 1.1 cgd */ 46 1.1 cgd 47 1.1 cgd ENTRY(bzero) 48 1.1 cgd pushl %edi 49 1.6 mycroft movl 8(%esp),%edi 50 1.6 mycroft movl 12(%esp),%edx 51 1.1 cgd 52 1.1 cgd cld /* set fill direction forward */ 53 1.1 cgd xorl %eax,%eax /* set fill data to 0 */ 54 1.1 cgd 55 1.1 cgd /* 56 1.1 cgd * if the string is too short, it's really not worth the overhead 57 1.3 jtc * of aligning to word boundries, etc. So we jump to a plain 58 1.1 cgd * unaligned set. 59 1.1 cgd */ 60 1.6 mycroft cmpl $16,%edx 61 1.6 mycroft jb L1 62 1.1 cgd 63 1.6 mycroft movl %edi,%ecx /* compute misalignment */ 64 1.6 mycroft negl %ecx 65 1.6 mycroft andl $3,%ecx 66 1.6 mycroft subl %ecx,%edx 67 1.6 mycroft rep /* zero until word aligned */ 68 1.1 cgd stosb 69 1.1 cgd 70 1.6 mycroft movl %edx,%ecx /* zero by words */ 71 1.1 cgd shrl $2,%ecx 72 1.6 mycroft andl $3,%edx 73 1.1 cgd rep 74 1.1 cgd stosl 75 1.1 cgd 76 1.6 mycroft L1: movl %edx,%ecx /* zero remainder by bytes */ 77 1.6 mycroft rep 78 1.1 cgd stosb 79 1.1 cgd 80 1.1 cgd popl %edi 81 1.1 cgd ret 82
Indexes created Mon Sep 29 21:09:56 GMT 2025