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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)memset.c 8.1 (Berkeley) 6/4/93 37 * $FreeBSD: src/lib/libc/string/memset.c,v 1.4.2.1 2001/07/09 23:30:03 obrien Exp $ 38 * $DragonFly: src/lib/libc/string/memset.c,v 1.4 2005/09/18 16:32:34 asmodai Exp $ 39 */ 40 41 #include <sys/types.h> 42 43 #include <limits.h> 44 #include <string.h> 45 46 #define wsize sizeof(u_int) 47 #define wmask (wsize - 1) 48 49 #ifdef BZERO 50 #define RETURN return 51 #define VAL 0 52 #define WIDEVAL 0 53 54 void 55 bzero(void *dst0, size_t length) 56 #else 57 #define RETURN return (dst0) 58 #define VAL c0 59 #define WIDEVAL c 60 61 void * 62 memset(void *dst0, int c0, size_t length) 63 #endif 64 { 65 size_t t; 66 #ifndef BZERO 67 u_int c; 68 #endif 69 u_char *dst; 70 71 dst = dst0; 72 /* 73 * If not enough words, just fill bytes. A length >= 2 words 74 * guarantees that at least one of them is `complete' after 75 * any necessary alignment. For instance: 76 * 77 * |-----------|-----------|-----------| 78 * |00|01|02|03|04|05|06|07|08|09|0A|00| 79 * ^---------------------^ 80 * dst dst+length-1 81 * 82 * but we use a minimum of 3 here since the overhead of the code 83 * to do word writes is substantial. 84 */ 85 if (length < 3 * wsize) { 86 while (length != 0) { 87 *dst++ = VAL; 88 --length; 89 } 90 RETURN; 91 } 92 93 #ifndef BZERO 94 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 95 c = (c << 8) | c; /* u_int is 16 bits. */ 96 #if UINT_MAX > 0xffff 97 c = (c << 16) | c; /* u_int is 32 bits. */ 98 #endif 99 #if UINT_MAX > 0xffffffff 100 c = (c << 32) | c; /* u_int is 64 bits. */ 101 #endif 102 } 103 #endif 104 /* Align destination by filling in bytes. */ 105 if ((t = (long)dst & wmask) != 0) { 106 t = wsize - t; 107 length -= t; 108 do { 109 *dst++ = VAL; 110 } while (--t != 0); 111 } 112 113 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 114 t = length / wsize; 115 do { 116 *(u_int *)dst = WIDEVAL; 117 dst += wsize; 118 } while (--t != 0); 119 120 /* Mop up trailing bytes, if any. */ 121 t = length & wmask; 122 if (t != 0) 123 do { 124 *dst++ = VAL; 125 } while (--t != 0); 126 RETURN; 127 } 128