1 /* $OpenBSD: memset.c,v 1.5 2004/08/07 00:38:32 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/cdefs.h>
37 #if defined(LIBC_SCCS) && !defined(lint)
38 #if 0
39 static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93";
40 #else
41 __RCSID("$NetBSD: memset.c,v 1.6 1998/03/27 05:35:47 cgd Exp $");
42 #endif
43 #endif /* LIBC_SCCS and not lint */
44
45 #include <sys/types.h>
46
47 #if !defined(_KERNEL) && !defined(_STANDALONE)
48 #include <string.h>
49 #include <limits.h>
50 #else
51 #include <sys/limits.h>
52 #include <sys/systm.h>
53 #include <lib/libkern/libkern.h>
54 #endif
55
56 #define wsize sizeof(u_int)
57 #define wmask (wsize - 1)
58
59 #ifdef BZERO
60 #define RETURN return
61 #define VAL 0
62 #define WIDEVAL 0
63
64 void
65 bzero(void *dst0, size_t length)
66 #else
67 #define RETURN return (dst0)
68 #define VAL c0
69 #define WIDEVAL c
70
71 void *
72 memset(void *dst0, int c0, size_t length)
73 #endif
74 {
75 size_t t;
76 #ifndef BZERO
77 u_int c;
78 #endif
79 u_char *dst;
80
81 dst = dst0;
82 /*
83 * If not enough words, just fill bytes. A length >= 2 words
84 * guarantees that at least one of them is `complete' after
85 * any necessary alignment. For instance:
86 *
87 * |-----------|-----------|-----------|
88 * |00|01|02|03|04|05|06|07|08|09|0A|00|
89 * ^---------------------^
90 * dst dst+length-1
91 *
92 * but we use a minimum of 3 here since the overhead of the code
93 * to do word writes is substantial.
94 */
95 if (length < 3 * wsize) {
96 while (length != 0) {
97 *dst++ = VAL;
98 --length;
99 }
100 RETURN;
101 }
102
103 #ifndef BZERO
104 if ((c = (u_char)c0) != 0) { /* Fill the word. */
105 c = (c << 8) | c; /* u_int is 16 bits. */
106 #if UINT_MAX > 0xffff
107 c = (c << 16) | c; /* u_int is 32 bits. */
108 #endif
109 #if UINT_MAX > 0xffffffff
110 c = (c << 32) | c; /* u_int is 64 bits. */
111 #endif
112 }
113 #endif
114 /* Align destination by filling in bytes. */
115 if ((t = (u_long)dst & wmask) != 0) {
116 t = wsize - t;
117 length -= t;
118 do {
119 *dst++ = VAL;
120 } while (--t != 0);
121 }
122
123 /* Fill words. Length was >= 2*words so we know t >= 1 here. */
124 t = length / wsize;
125 do {
126 *(u_int *)dst = WIDEVAL;
127 dst += wsize;
128 } while (--t != 0);
129
130 /* Mop up trailing bytes, if any. */
131 t = length & wmask;
132 if (t != 0)
133 do {
134 *dst++ = VAL;
135 } while (--t != 0);
136 RETURN;
137 }