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 #undef bzero /* _FORTIFY_SOURCE */ 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 #undef memset /* _FORTIFY_SOURCE */ 57 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_long 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 * TODO: This threshold might not be sensible for 64-bit u_long. 87 * We should benchmark and revisit this decision. 88 */ 89 if (length < 3 * wsize) { 90 while (length != 0) { 91 *dst++ = VAL; 92 --length; 93 } 94 RETURN; 95 } 96 97 #ifndef BZERO 98 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 99 c = (c << 8) | c; /* u_long is 16 bits. */ 100 #if ULONG_MAX > 0xffff 101 c = (c << 16) | c; /* u_long is 32 bits. */ 102 #endif 103 #if ULONG_MAX > 0xffffffff 104 c = (c << 32) | c; /* u_long is 64 bits. */ 105 #endif 106 } 107 #endif 108 /* Align destination by filling in bytes. */ 109 if ((t = (long)dst & wmask) != 0) { 110 t = wsize - t; 111 length -= t; 112 do { 113 *dst++ = VAL; 114 } while (--t != 0); 115 } 116 117 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 118 t = length / wsize; 119 do { 120 *(u_long *)(void *)dst = WIDEVAL; 121 dst += wsize; 122 } while (--t != 0); 123 124 /* Mop up trailing bytes, if any. */ 125 t = length & wmask; 126 if (t != 0) 127 do { 128 *dst++ = VAL; 129 } while (--t != 0); 130 RETURN; 131 } 132