1 /* $OpenBSD: memset.c,v 1.7 2014/06/10 04:16:57 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 #include <sys/limits.h> 39 #include <sys/systm.h> 40 #include <lib/libkern/libkern.h> 41 42 #define wsize sizeof(u_int) 43 #define wmask (wsize - 1) 44 45 #ifdef BZERO 46 #define RETURN return 47 #define VAL 0 48 #define WIDEVAL 0 49 50 void 51 bzero(void *dst0, size_t length) 52 #else 53 #define RETURN return (dst0) 54 #define VAL c0 55 #define WIDEVAL c 56 57 void * 58 memset(void *dst0, int c0, size_t length) 59 #endif 60 { 61 size_t t; 62 #ifndef BZERO 63 u_int c; 64 #endif 65 u_char *dst; 66 67 dst = dst0; 68 /* 69 * If not enough words, just fill bytes. A length >= 2 words 70 * guarantees that at least one of them is `complete' after 71 * any necessary alignment. For instance: 72 * 73 * |-----------|-----------|-----------| 74 * |00|01|02|03|04|05|06|07|08|09|0A|00| 75 * ^---------------------^ 76 * dst dst+length-1 77 * 78 * but we use a minimum of 3 here since the overhead of the code 79 * to do word writes is substantial. 80 */ 81 if (length < 3 * wsize) { 82 while (length != 0) { 83 *dst++ = VAL; 84 --length; 85 } 86 RETURN; 87 } 88 89 #ifndef BZERO 90 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 91 c = (c << 8) | c; /* u_int is 16 bits. */ 92 #if UINT_MAX > 0xffff 93 c = (c << 16) | c; /* u_int is 32 bits. */ 94 #endif 95 #if UINT_MAX > 0xffffffff 96 c = (c << 32) | c; /* u_int is 64 bits. */ 97 #endif 98 } 99 #endif 100 /* Align destination by filling in bytes. */ 101 if ((t = (u_long)dst & wmask) != 0) { 102 t = wsize - t; 103 length -= t; 104 do { 105 *dst++ = VAL; 106 } while (--t != 0); 107 } 108 109 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 110 t = length / wsize; 111 do { 112 *(u_int *)dst = WIDEVAL; 113 dst += wsize; 114 } while (--t != 0); 115 116 /* Mop up trailing bytes, if any. */ 117 t = length & wmask; 118 if (t != 0) 119 do { 120 *dst++ = VAL; 121 } while (--t != 0); 122 RETURN; 123 } 124