1 /* $OpenBSD: memset.c,v 1.6 2009/10/27 23:59:35 deraadt 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/types.h> 37 38 #if !defined(_KERNEL) && !defined(_STANDALONE) 39 #include <string.h> 40 #include <limits.h> 41 #else 42 #include <sys/limits.h> 43 #include <sys/systm.h> 44 #include <lib/libkern/libkern.h> 45 #endif 46 47 #define wsize sizeof(u_int) 48 #define wmask (wsize - 1) 49 50 #ifdef BZERO 51 #define RETURN return 52 #define VAL 0 53 #define WIDEVAL 0 54 55 void 56 bzero(void *dst0, size_t length) 57 #else 58 #define RETURN return (dst0) 59 #define VAL c0 60 #define WIDEVAL c 61 62 void * 63 memset(void *dst0, int c0, size_t length) 64 #endif 65 { 66 size_t t; 67 #ifndef BZERO 68 u_int c; 69 #endif 70 u_char *dst; 71 72 dst = dst0; 73 /* 74 * If not enough words, just fill bytes. A length >= 2 words 75 * guarantees that at least one of them is `complete' after 76 * any necessary alignment. For instance: 77 * 78 * |-----------|-----------|-----------| 79 * |00|01|02|03|04|05|06|07|08|09|0A|00| 80 * ^---------------------^ 81 * dst dst+length-1 82 * 83 * but we use a minimum of 3 here since the overhead of the code 84 * to do word writes is substantial. 85 */ 86 if (length < 3 * wsize) { 87 while (length != 0) { 88 *dst++ = VAL; 89 --length; 90 } 91 RETURN; 92 } 93 94 #ifndef BZERO 95 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 96 c = (c << 8) | c; /* u_int is 16 bits. */ 97 #if UINT_MAX > 0xffff 98 c = (c << 16) | c; /* u_int is 32 bits. */ 99 #endif 100 #if UINT_MAX > 0xffffffff 101 c = (c << 32) | c; /* u_int is 64 bits. */ 102 #endif 103 } 104 #endif 105 /* Align destination by filling in bytes. */ 106 if ((t = (u_long)dst & wmask) != 0) { 107 t = wsize - t; 108 length -= t; 109 do { 110 *dst++ = VAL; 111 } while (--t != 0); 112 } 113 114 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 115 t = length / wsize; 116 do { 117 *(u_int *)dst = WIDEVAL; 118 dst += wsize; 119 } while (--t != 0); 120 121 /* Mop up trailing bytes, if any. */ 122 t = length & wmask; 123 if (t != 0) 124 do { 125 *dst++ = VAL; 126 } while (--t != 0); 127 RETURN; 128 } 129