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 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40
41 #include <sys/types.h>
42
43 #include <limits.h>
44
45 #define wsize sizeof(u_long)
46 #define wmask (wsize - 1)
47
48 #ifdef BZERO
49 #include <strings.h>
50
51 #define RETURN return
52 #define VAL 0
53 #define WIDEVAL 0
54
55 void
bzero(void * dst0,size_t length)56 bzero(void *dst0, size_t length)
57 #else
58 #include <string.h>
59
60 #define RETURN return (dst0)
61 #define VAL c0
62 #define WIDEVAL c
63
64 void *
65 memset(void *dst0, int c0, size_t length)
66 #endif
67 {
68 size_t t;
69 #ifndef BZERO
70 u_long c;
71 #endif
72 u_char *dst;
73
74 dst = dst0;
75 /*
76 * If not enough words, just fill bytes. A length >= 2 words
77 * guarantees that at least one of them is `complete' after
78 * any necessary alignment. For instance:
79 *
80 * |-----------|-----------|-----------|
81 * |00|01|02|03|04|05|06|07|08|09|0A|00|
82 * ^---------------------^
83 * dst dst+length-1
84 *
85 * but we use a minimum of 3 here since the overhead of the code
86 * to do word writes is substantial.
87 *
88 * TODO: This threshold might not be sensible for 64-bit u_long.
89 * We should benchmark and revisit this decision.
90 */
91 if (length < 3 * wsize) {
92 while (length != 0) {
93 *dst++ = VAL;
94 --length;
95 }
96 RETURN;
97 }
98
99 #ifndef BZERO
100 if ((c = (u_char)c0) != 0) { /* Fill the word. */
101 c = (c << 8) | c; /* u_long is 16 bits. */
102 #if ULONG_MAX > 0xffff
103 c = (c << 16) | c; /* u_long is 32 bits. */
104 #endif
105 #if ULONG_MAX > 0xffffffff
106 c = (c << 32) | c; /* u_long is 64 bits. */
107 #endif
108 }
109 #endif
110 /* Align destination by filling in bytes. */
111 if ((t = (long)dst & wmask) != 0) {
112 t = wsize - t;
113 length -= t;
114 do {
115 *dst++ = VAL;
116 } while (--t != 0);
117 }
118
119 /* Fill words. Length was >= 2*words so we know t >= 1 here. */
120 t = length / wsize;
121 do {
122 *(u_long *)(void *)dst = WIDEVAL;
123 dst += wsize;
124 } while (--t != 0);
125
126 /* Mop up trailing bytes, if any. */
127 t = length & wmask;
128 if (t != 0)
129 do {
130 *dst++ = VAL;
131 } while (--t != 0);
132 RETURN;
133 }
134