1 /* $NetBSD: memset.c,v 1.1 2005/12/20 19:28:52 christos 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 __RCSID("$NetBSD: memset.c,v 1.1 2005/12/20 19:28:52 christos Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <sys/types.h> 45 46 #if !defined(_KERNEL) && !defined(_STANDALONE) 47 #include <assert.h> 48 #include <limits.h> 49 #include <string.h> 50 #else 51 #include <lib/libkern/libkern.h> 52 #include <machine/limits.h> 53 #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 63 void 64 bzero(dst0, length) 65 void *dst0; 66 size_t length; 67 #else 68 #define RETURN return (dst0) 69 #define VAL c0 70 #define WIDEVAL c 71 72 void * 73 memset(dst0, c0, length) 74 void *dst0; 75 int c0; 76 size_t length; 77 #endif 78 { 79 size_t t; 80 #ifndef BZERO 81 u_int c; 82 #endif 83 u_char *dst; 84 85 _DIAGASSERT(dst0 != 0); 86 87 dst = dst0; 88 /* 89 * If not enough words, just fill bytes. A length >= 2 words 90 * guarantees that at least one of them is `complete' after 91 * any necessary alignment. For instance: 92 * 93 * |-----------|-----------|-----------| 94 * |00|01|02|03|04|05|06|07|08|09|0A|00| 95 * ^---------------------^ 96 * dst dst+length-1 97 * 98 * but we use a minimum of 3 here since the overhead of the code 99 * to do word writes is substantial. 100 */ 101 if (length < 3 * wsize) { 102 while (length != 0) { 103 *dst++ = VAL; 104 --length; 105 } 106 RETURN; 107 } 108 109 #ifndef BZERO 110 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 111 c = (c << 8) | c; /* u_int is 16 bits. */ 112 #if UINT_MAX > 0xffff 113 c = (c << 16) | c; /* u_int is 32 bits. */ 114 #endif 115 #if UINT_MAX > 0xffffffff 116 c = (c << 32) | c; /* u_int is 64 bits. */ 117 #endif 118 } 119 #endif 120 /* Align destination by filling in bytes. */ 121 if ((t = (size_t)((u_long)dst & wmask)) != 0) { 122 t = wsize - t; 123 length -= t; 124 do { 125 *dst++ = VAL; 126 } while (--t != 0); 127 } 128 129 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 130 t = length / wsize; 131 do { 132 *(u_int *)(void *)dst = WIDEVAL; 133 dst += wsize; 134 } while (--t != 0); 135 136 /* Mop up trailing bytes, if any. */ 137 t = length & wmask; 138 if (t != 0) 139 do { 140 *dst++ = VAL; 141 } while (--t != 0); 142 RETURN; 143 } 144