1/* $NetBSD: memset.S,v 1.3 2007/11/12 18:41:59 ad Exp $ */ 2 3/*- 4 * Copyright (c) 2003 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by David Laight. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32#include <machine/asm.h> 33 34#if defined(LIBC_SCCS) 35 RCSID("$NetBSD: memset.S,v 1.3 2007/11/12 18:41:59 ad Exp $") 36#endif 37 38#ifdef BZERO 39ENTRY(bzero) 40#else 41ENTRY(memset) 42#endif 43#ifdef BZERO 44 movl 8(%esp),%ecx 45 xor %eax,%eax 46#else 47 movl 12(%esp),%ecx 48 movzbl 8(%esp),%eax /* unsigned char, zero extend */ 49#endif 50 cmpl $0x0f,%ecx /* avoid mispredicted branch... */ 51 52 pushl %edi 53 movl 8(%esp),%edi 54 55 /* 56 * if the string is too short, it's really not worth the overhead 57 * of aligning to word boundries, etc. So we jump to a plain 58 * unaligned set. 59 * 60 * NB aligning the transfer is actually pointless on my athlon 700, 61 * It does make a difference to a PII though. 62 * 63 * The PII, PIII and PIV all seem to have a massive performance 64 * drop when the initial target address is an odd multiple of 4. 65 */ 66 jbe .Lby_bytes 67 68#ifndef BZERO 69 movb %al,%ah /* copy char to all bytes in word */ 70 movl %eax,%edx 71 sall $16,%eax 72 orl %edx,%eax 73#endif 74 75 movl %edi,%edx /* detect misalignment */ 76 neg %edx 77 andl $7,%edx 78 jnz .Lalign 79.Laligned: 80 movl %eax,-4(%edi,%ecx) /* zap last 4 bytes */ 81 shrl $2,%ecx /* zero by words */ 82 rep 83 stosl 84.Ldone: 85#ifndef BZERO 86 movl 8(%esp),%eax /* return address of buffer */ 87#endif 88 pop %edi 89 ret 90 91.Lalign: 92 movl %eax,(%edi) /* zap first 8 bytes */ 93 movl %eax,4(%edi) 94 subl %edx,%ecx /* remove from main count */ 95 add %edx,%edi 96 jmp .Laligned 97 98.Lby_bytes: 99 rep 100 stosb 101 102#ifndef BZERO 103 movl 8(%esp),%eax /* return address of buffer */ 104#endif 105 popl %edi 106 ret 107