bzero.S revision 1849
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 * 301849Swollman * $Id: bzero.S,v 1.1 1993/12/05 13:01:42 ats Exp $ 311849Swollman */ 321849Swollman 331849Swollman#if defined(LIBC_RCS) && !defined(lint) 341849Swollman .asciz "$Id: bzero.S,v 1.1 1993/12/05 13:01:42 ats Exp $" 351849Swollman#endif /* LIBC_RCS and not lint */ 361849Swollman 371849Swollman#include "DEFS.h" 381849Swollman 391849Swollman/* 401849Swollman * bzero (void *b, size_t len) 411849Swollman * write len zero bytes to the string b. 421849Swollman * 431849Swollman * Written by: 441849Swollman * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 451849Swollman */ 461849Swollman 471849SwollmanENTRY(bzero) 481849Swollman pushl %edi 491849Swollman pushl %ebx 501849Swollman movl 12(%esp),%edi 511849Swollman movl 16(%esp),%ecx 521849Swollman 531849Swollman cld /* set fill direction forward */ 541849Swollman xorl %eax,%eax /* set fill data to 0 */ 551849Swollman 561849Swollman /* 571849Swollman * if the string is too short, it's really not worth the overhead 581849Swollman * of aligning to word boundries, etc. So we jump to a plain 591849Swollman * unaligned set. 601849Swollman */ 611849Swollman cmpl $0x0f,%ecx 621849Swollman jle L1 631849Swollman 641849Swollman movl %edi,%edx /* compute misalignment */ 651849Swollman negl %edx 661849Swollman andl $3,%edx 671849Swollman movl %ecx,%ebx 681849Swollman subl %edx,%ebx 691849Swollman 701849Swollman movl %edx,%ecx /* zero until word aligned */ 711849Swollman rep 721849Swollman stosb 731849Swollman 741849Swollman movl %ebx,%ecx /* zero by words */ 751849Swollman shrl $2,%ecx 761849Swollman rep 771849Swollman stosl 781849Swollman 791849Swollman movl %ebx,%ecx 801849Swollman andl $3,%ecx /* zero remainder by bytes */ 811849SwollmanL1: rep 821849Swollman stosb 831849Swollman 841849Swollman popl %ebx 851849Swollman popl %edi 861849Swollman ret 87