1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/types.h> 36 37 #include <limits.h> 38 39 #define wsize sizeof(u_long) 40 #define wmask (wsize - 1) 41 42 #ifdef BZERO 43 #include <strings.h> 44 45 #define RETURN return 46 #define VAL 0 47 #define WIDEVAL 0 48 49 void 50 bzero(void *dst0, size_t length) 51 #else 52 #include <string.h> 53 54 #define RETURN return (dst0) 55 #define VAL c0 56 #define WIDEVAL c 57 58 void * 59 memset(void *dst0, int c0, size_t length) 60 #endif 61 { 62 size_t t; 63 #ifndef BZERO 64 u_long c; 65 #endif 66 u_char *dst; 67 68 dst = dst0; 69 /* 70 * If not enough words, just fill bytes. A length >= 2 words 71 * guarantees that at least one of them is `complete' after 72 * any necessary alignment. For instance: 73 * 74 * |-----------|-----------|-----------| 75 * |00|01|02|03|04|05|06|07|08|09|0A|00| 76 * ^---------------------^ 77 * dst dst+length-1 78 * 79 * but we use a minimum of 3 here since the overhead of the code 80 * to do word writes is substantial. 81 * 82 * TODO: This threshold might not be sensible for 64-bit u_long. 83 * We should benchmark and revisit this decision. 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_long is 16 bits. */ 96 #if ULONG_MAX > 0xffff 97 c = (c << 16) | c; /* u_long is 32 bits. */ 98 #endif 99 #if ULONG_MAX > 0xffffffff 100 c = (c << 32) | c; /* u_long 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_long *)(void *)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