1 /* $OpenBSD: memset.c,v 1.3 2002/04/24 21:53:12 espie Exp $ */ 2 /* $NetBSD: memset.c,v 1.6 1998/03/27 05:35:47 cgd Exp $ */ 3 4 /*- 5 * Copyright (c) 1990, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Mike Hibler and Chris Torek. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 #include <sys/cdefs.h> 41 #if defined(LIBC_SCCS) && !defined(lint) 42 #if 0 43 static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; 44 #else 45 __RCSID("$NetBSD: memset.c,v 1.6 1998/03/27 05:35:47 cgd Exp $"); 46 #endif 47 #endif /* LIBC_SCCS and not lint */ 48 49 #include <sys/types.h> 50 51 #if !defined(_KERNEL) && !defined(_STANDALONE) 52 #include <string.h> 53 #include <limits.h> 54 #else 55 #include <sys/limits.h> 56 #include <sys/systm.h> 57 #include <lib/libkern/libkern.h> 58 #endif 59 60 #define wsize sizeof(u_int) 61 #define wmask (wsize - 1) 62 63 #ifdef BZERO 64 #define RETURN return 65 #define VAL 0 66 #define WIDEVAL 0 67 68 void 69 bzero(dst0, length) 70 void *dst0; 71 size_t length; 72 #else 73 #define RETURN return (dst0) 74 #define VAL c0 75 #define WIDEVAL c 76 77 void * 78 memset(dst0, c0, length) 79 void *dst0; 80 int c0; 81 size_t length; 82 #endif 83 { 84 size_t t; 85 #ifndef BZERO 86 u_int c; 87 #endif 88 u_char *dst; 89 90 dst = dst0; 91 /* 92 * If not enough words, just fill bytes. A length >= 2 words 93 * guarantees that at least one of them is `complete' after 94 * any necessary alignment. For instance: 95 * 96 * |-----------|-----------|-----------| 97 * |00|01|02|03|04|05|06|07|08|09|0A|00| 98 * ^---------------------^ 99 * dst dst+length-1 100 * 101 * but we use a minimum of 3 here since the overhead of the code 102 * to do word writes is substantial. 103 */ 104 if (length < 3 * wsize) { 105 while (length != 0) { 106 *dst++ = VAL; 107 --length; 108 } 109 RETURN; 110 } 111 112 #ifndef BZERO 113 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 114 c = (c << 8) | c; /* u_int is 16 bits. */ 115 #if UINT_MAX > 0xffff 116 c = (c << 16) | c; /* u_int is 32 bits. */ 117 #endif 118 #if UINT_MAX > 0xffffffff 119 c = (c << 32) | c; /* u_int is 64 bits. */ 120 #endif 121 } 122 #endif 123 /* Align destination by filling in bytes. */ 124 if ((t = (u_long)dst & wmask) != 0) { 125 t = wsize - t; 126 length -= t; 127 do { 128 *dst++ = VAL; 129 } while (--t != 0); 130 } 131 132 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 133 t = length / wsize; 134 do { 135 *(u_int *)dst = WIDEVAL; 136 dst += wsize; 137 } while (--t != 0); 138 139 /* Mop up trailing bytes, if any. */ 140 t = length & wmask; 141 if (t != 0) 142 do { 143 *dst++ = VAL; 144 } while (--t != 0); 145 RETURN; 146 } 147