bzero.S revision 5790
11849Swollman/* 21849Swollman * Copyright (c) 1993 Winning Strategies, Inc. 31849Swollman * All rights reserved. 41849Swollman * 51849Swollman * Redistribution and use in source and binary forms, with or without 61849Swollman * modification, are permitted provided that the following conditions 71849Swollman * are met: 81849Swollman * 1. Redistributions of source code must retain the above copyright 91849Swollman * notice, this list of conditions and the following disclaimer. 101849Swollman * 2. Redistributions in binary form must reproduce the above copyright 111849Swollman * notice, this list of conditions and the following disclaimer in the 121849Swollman * documentation and/or other materials provided with the distribution. 131849Swollman * 3. All advertising materials mentioning features or use of this software 141849Swollman * must display the following acknowledgement: 151849Swollman * This product includes software developed by Winning Strategies, Inc. 161849Swollman * 4. The name of the author may not be used to endorse or promote products 171849Swollman * derived from this software withough specific prior written permission 181849Swollman * 191849Swollman * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 201849Swollman * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 211849Swollman * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 221849Swollman * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 231849Swollman * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 241849Swollman * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 251849Swollman * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 261849Swollman * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 271849Swollman * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 281849Swollman * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 291849Swollman * 305790Sdg * $Id: bzero.S,v 1.1 1994/08/05 01:18:25 wollman Exp $ 311849Swollman */ 321849Swollman 331849Swollman#if defined(LIBC_RCS) && !defined(lint) 345790Sdg .text 355790Sdg .asciz "$Id: bzero.S,v 1.1 1994/08/05 01:18:25 wollman Exp $" 361849Swollman#endif /* LIBC_RCS and not lint */ 371849Swollman 381849Swollman#include "DEFS.h" 391849Swollman 401849Swollman/* 411849Swollman * bzero (void *b, size_t len) 421849Swollman * write len zero bytes to the string b. 431849Swollman * 441849Swollman * Written by: 451849Swollman * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 461849Swollman */ 471849Swollman 481849SwollmanENTRY(bzero) 491849Swollman pushl %edi 501849Swollman pushl %ebx 511849Swollman movl 12(%esp),%edi 521849Swollman movl 16(%esp),%ecx 531849Swollman 541849Swollman cld /* set fill direction forward */ 551849Swollman xorl %eax,%eax /* set fill data to 0 */ 561849Swollman 571849Swollman /* 581849Swollman * if the string is too short, it's really not worth the overhead 591849Swollman * of aligning to word boundries, etc. So we jump to a plain 601849Swollman * unaligned set. 611849Swollman */ 621849Swollman cmpl $0x0f,%ecx 631849Swollman jle L1 641849Swollman 651849Swollman movl %edi,%edx /* compute misalignment */ 661849Swollman negl %edx 671849Swollman andl $3,%edx 681849Swollman movl %ecx,%ebx 691849Swollman subl %edx,%ebx 701849Swollman 711849Swollman movl %edx,%ecx /* zero until word aligned */ 721849Swollman rep 731849Swollman stosb 741849Swollman 751849Swollman movl %ebx,%ecx /* zero by words */ 761849Swollman shrl $2,%ecx 771849Swollman rep 781849Swollman stosl 791849Swollman 801849Swollman movl %ebx,%ecx 811849Swollman andl $3,%ecx /* zero remainder by bytes */ 821849SwollmanL1: rep 831849Swollman stosb 841849Swollman 851849Swollman popl %ebx 861849Swollman popl %edi 871849Swollman ret 88