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
bzero(void * dst0,size_t length)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