1 /* $OpenBSD: memset.c,v 1.8 2017/01/24 08:09:05 kettenis 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/types.h>
37
38 #include <sys/limits.h>
39 #include <sys/systm.h>
40 #include <lib/libkern/libkern.h>
41
42 #undef bzero
43 #undef memset
44
45 #define wsize sizeof(u_int)
46 #define wmask (wsize - 1)
47
48 #ifdef BZERO
49 #define RETURN return
50 #define VAL 0
51 #define WIDEVAL 0
52
53 void
bzero(void * dst0,size_t length)54 bzero(void *dst0, size_t length)
55 #else
56 #define RETURN return (dst0)
57 #define VAL c0
58 #define WIDEVAL c
59
60 void *
61 memset(void *dst0, int c0, size_t length)
62 #endif
63 {
64 size_t t;
65 #ifndef BZERO
66 u_int c;
67 #endif
68 u_char *dst;
69
70 dst = dst0;
71 /*
72 * If not enough words, just fill bytes. A length >= 2 words
73 * guarantees that at least one of them is `complete' after
74 * any necessary alignment. For instance:
75 *
76 * |-----------|-----------|-----------|
77 * |00|01|02|03|04|05|06|07|08|09|0A|00|
78 * ^---------------------^
79 * dst dst+length-1
80 *
81 * but we use a minimum of 3 here since the overhead of the code
82 * to do word writes is substantial.
83 */
84 if (length < 3 * wsize) {
85 while (length != 0) {
86 *dst++ = VAL;
87 --length;
88 }
89 RETURN;
90 }
91
92 #ifndef BZERO
93 if ((c = (u_char)c0) != 0) { /* Fill the word. */
94 c = (c << 8) | c; /* u_int is 16 bits. */
95 #if UINT_MAX > 0xffff
96 c = (c << 16) | c; /* u_int is 32 bits. */
97 #endif
98 #if UINT_MAX > 0xffffffff
99 c = (c << 32) | c; /* u_int is 64 bits. */
100 #endif
101 }
102 #endif
103 /* Align destination by filling in bytes. */
104 if ((t = (u_long)dst & wmask) != 0) {
105 t = wsize - t;
106 length -= t;
107 do {
108 *dst++ = VAL;
109 } while (--t != 0);
110 }
111
112 /* Fill words. Length was >= 2*words so we know t >= 1 here. */
113 t = length / wsize;
114 do {
115 *(u_int *)dst = WIDEVAL;
116 dst += wsize;
117 } while (--t != 0);
118
119 /* Mop up trailing bytes, if any. */
120 t = length & wmask;
121 if (t != 0)
122 do {
123 *dst++ = VAL;
124 } while (--t != 0);
125 RETURN;
126 }
127