1 /* $NetBSD: memset.c,v 1.6 1998/03/27 05:35:47 cgd 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 <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; 43 #else 44 __RCSID("$NetBSD: memset.c,v 1.6 1998/03/27 05:35:47 cgd Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include <sys/types.h> 49 50 #if !defined(_KERNEL) && !defined(_STANDALONE) 51 #include <string.h> 52 #include <limits.h> 53 #else 54 #include <lib/libkern/libkern.h> 55 #include <machine/limits.h> 56 #endif 57 58 #define wsize sizeof(u_int) 59 #define wmask (wsize - 1) 60 61 #ifdef BZERO 62 #define RETURN return 63 #define VAL 0 64 #define WIDEVAL 0 65 66 void 67 bzero(dst0, length) 68 void *dst0; 69 size_t length; 70 #else 71 #define RETURN return (dst0) 72 #define VAL c0 73 #define WIDEVAL c 74 75 void * 76 memset(dst0, c0, length) 77 void *dst0; 78 int c0; 79 size_t length; 80 #endif 81 { 82 size_t t; 83 u_int c; 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