1 /* $OpenBSD: memset.c,v 1.4 2003/06/02 23:28:08 millert 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. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; 40 #else 41 __RCSID("$NetBSD: memset.c,v 1.6 1998/03/27 05:35:47 cgd Exp $"); 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <sys/types.h> 46 47 #if !defined(_KERNEL) && !defined(_STANDALONE) 48 #include <string.h> 49 #include <limits.h> 50 #else 51 #include <sys/limits.h> 52 #include <sys/systm.h> 53 #include <lib/libkern/libkern.h> 54 #endif 55 56 #define wsize sizeof(u_int) 57 #define wmask (wsize - 1) 58 59 #ifdef BZERO 60 #define RETURN return 61 #define VAL 0 62 #define WIDEVAL 0 63 64 void 65 bzero(dst0, length) 66 void *dst0; 67 size_t length; 68 #else 69 #define RETURN return (dst0) 70 #define VAL c0 71 #define WIDEVAL c 72 73 void * 74 memset(dst0, c0, length) 75 void *dst0; 76 int c0; 77 size_t length; 78 #endif 79 { 80 size_t t; 81 #ifndef BZERO 82 u_int c; 83 #endif 84 u_char *dst; 85 86 dst = dst0; 87 /* 88 * If not enough words, just fill bytes. A length >= 2 words 89 * guarantees that at least one of them is `complete' after 90 * any necessary alignment. For instance: 91 * 92 * |-----------|-----------|-----------| 93 * |00|01|02|03|04|05|06|07|08|09|0A|00| 94 * ^---------------------^ 95 * dst dst+length-1 96 * 97 * but we use a minimum of 3 here since the overhead of the code 98 * to do word writes is substantial. 99 */ 100 if (length < 3 * wsize) { 101 while (length != 0) { 102 *dst++ = VAL; 103 --length; 104 } 105 RETURN; 106 } 107 108 #ifndef BZERO 109 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 110 c = (c << 8) | c; /* u_int is 16 bits. */ 111 #if UINT_MAX > 0xffff 112 c = (c << 16) | c; /* u_int is 32 bits. */ 113 #endif 114 #if UINT_MAX > 0xffffffff 115 c = (c << 32) | c; /* u_int is 64 bits. */ 116 #endif 117 } 118 #endif 119 /* Align destination by filling in bytes. */ 120 if ((t = (u_long)dst & wmask) != 0) { 121 t = wsize - t; 122 length -= t; 123 do { 124 *dst++ = VAL; 125 } while (--t != 0); 126 } 127 128 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 129 t = length / wsize; 130 do { 131 *(u_int *)dst = WIDEVAL; 132 dst += wsize; 133 } while (--t != 0); 134 135 /* Mop up trailing bytes, if any. */ 136 t = length & wmask; 137 if (t != 0) 138 do { 139 *dst++ = VAL; 140 } while (--t != 0); 141 RETURN; 142 } 143