1/* $NetBSD: memset.c,v 1.1.1.2 2008/05/18 14:29:38 aymeric Exp $ */ 2 3/*- 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Mike Hibler and Chris Torek. 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39#include "config.h" 40 41#if defined(LIBC_SCCS) && !defined(lint) 42static const char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; 43#endif /* LIBC_SCCS and not lint */ 44 45#include <sys/types.h> 46 47#include <limits.h> 48#include <string.h> 49 50/* 51 * PUBLIC: #ifndef HAVE_MEMSET 52 * PUBLIC: void *memset __P((void *, int, size_t)); 53 * PUBLIC: #endif 54 */ 55#define wsize sizeof(u_int) 56#define wmask (wsize - 1) 57 58#ifdef BZERO 59#define RETURN return 60#define VAL 0 61#define WIDEVAL 0 62 63void 64bzero(dst0, length) 65 void *dst0; 66 register size_t length; 67#else 68#define RETURN return (dst0) 69#define VAL c0 70#define WIDEVAL c 71 72void * 73memset(void *dst0, register int c0, register size_t length) 74 75 76 77#endif 78{ 79 register size_t t; 80 register u_int c; 81 register u_char *dst; 82 83 dst = dst0; 84 /* 85 * If not enough words, just fill bytes. A length >= 2 words 86 * guarantees that at least one of them is `complete' after 87 * any necessary alignment. For instance: 88 * 89 * |-----------|-----------|-----------| 90 * |00|01|02|03|04|05|06|07|08|09|0A|00| 91 * ^---------------------^ 92 * dst dst+length-1 93 * 94 * but we use a minimum of 3 here since the overhead of the code 95 * to do word writes is substantial. 96 */ 97 if (length < 3 * wsize) { 98 while (length != 0) { 99 *dst++ = VAL; 100 --length; 101 } 102 RETURN; 103 } 104 105#ifndef BZERO 106 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 107 c = (c << 8) | c; /* u_int is 16 bits. */ 108#if UINT_MAX > 0xffff 109 c = (c << 16) | c; /* u_int is 32 bits. */ 110#endif 111#if UINT_MAX > 0xffffffff 112 c = (c << 32) | c; /* u_int is 64 bits. */ 113#endif 114 } 115#endif 116 /* Align destination by filling in bytes. */ 117 if ((t = (int)dst & wmask) != 0) { 118 t = wsize - t; 119 length -= t; 120 do { 121 *dst++ = VAL; 122 } while (--t != 0); 123 } 124 125 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 126 t = length / wsize; 127 do { 128 *(u_int *)dst = WIDEVAL; 129 dst += wsize; 130 } while (--t != 0); 131 132 /* Mop up trailing bytes, if any. */ 133 t = length & wmask; 134 if (t != 0) 135 do { 136 *dst++ = VAL; 137 } while (--t != 0); 138 RETURN; 139} 140