1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Mike Hibler and Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)memset.c 8.1 (Berkeley) 6/4/93 33 * $FreeBSD: src/lib/libc/string/memset.c,v 1.9 2007/01/09 00:28:12 imp Exp $ 34 * $DragonFly: src/lib/libc/string/memset.c,v 1.4 2005/09/18 16:32:34 asmodai Exp $ 35 */ 36 37 #include <sys/types.h> 38 39 #include <limits.h> 40 41 #define wsize sizeof(u_int) 42 #define wmask (wsize - 1) 43 44 #ifdef BZERO 45 #include <strings.h> 46 47 #define RETURN return 48 #define VAL 0 49 #define WIDEVAL 0 50 51 void 52 bzero(void *dst0, size_t length) 53 #else 54 #include <string.h> 55 56 #define RETURN return (dst0) 57 #define VAL c0 58 #define WIDEVAL c 59 60 void * 61 memset(void *dst0, int c0, size_t length) 62 #endif 63 { 64 size_t t; 65 #ifndef BZERO 66 u_int c; 67 #endif 68 u_char *dst; 69 70 dst = dst0; 71 /* 72 * If not enough words, just fill bytes. A length >= 2 words 73 * guarantees that at least one of them is `complete' after 74 * any necessary alignment. For instance: 75 * 76 * |-----------|-----------|-----------| 77 * |00|01|02|03|04|05|06|07|08|09|0A|00| 78 * ^---------------------^ 79 * dst dst+length-1 80 * 81 * but we use a minimum of 3 here since the overhead of the code 82 * to do word writes is substantial. 83 */ 84 if (length < 3 * wsize) { 85 while (length != 0) { 86 *dst++ = VAL; 87 --length; 88 } 89 RETURN; 90 } 91 92 #ifndef BZERO 93 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 94 c = (c << 8) | c; /* u_int is 16 bits. */ 95 #if UINT_MAX > 0xffff 96 c = (c << 16) | c; /* u_int is 32 bits. */ 97 #endif 98 #if UINT_MAX > 0xffffffff 99 c = (c << 32) | c; /* u_int is 64 bits. */ 100 #endif 101 } 102 #endif 103 /* Align destination by filling in bytes. */ 104 if ((t = (long)dst & wmask) != 0) { 105 t = wsize - t; 106 length -= t; 107 do { 108 *dst++ = VAL; 109 } while (--t != 0); 110 } 111 112 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 113 t = length / wsize; 114 do { 115 *(u_int *)dst = WIDEVAL; 116 dst += wsize; 117 } while (--t != 0); 118 119 /* Mop up trailing bytes, if any. */ 120 t = length & wmask; 121 if (t != 0) 122 do { 123 *dst++ = VAL; 124 } while (--t != 0); 125 RETURN; 126 } 127