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DEFINITIONS
This source file includes following definitions.
- bzero
1 /*
2 * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
3 * The President and Fellows of Harvard College.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 /*
31 * This file is shared between libc and the kernel, so don't put anything
32 * in here that won't work in both contexts.
33 */
34
35 #ifdef _KERNEL
36 #include <types.h>
37 #include <lib.h>
38 #else
39 #include <stdint.h>
40 #include <string.h>
41 #endif
42
43 /*
44 * Standard (well, semi-standard) C string function - zero a block of
45 * memory.
46 */
47
48 void
49 bzero(void *vblock, size_t len)
50 {
51 char *block = vblock;
52 size_t i;
53
54 /*
55 * For performance, optimize the common case where the pointer
56 * and the length are word-aligned, and write word-at-a-time
57 * instead of byte-at-a-time. Otherwise, write bytes.
58 *
59 * The alignment logic here should be portable. We rely on the
60 * compiler to be reasonably intelligent about optimizing the
61 * divides and moduli out. Fortunately, it is.
62 */
63
64 if ((uintptr_t)block % sizeof(long) == 0 &&
65 len % sizeof(long) == 0) {
66 long *lb = (long *)block;
67 for (i=0; i<len/sizeof(long); i++) {
68 lb[i] = 0;
69 }
70 }
71 else {
72 for (i=0; i<len; i++) {
73 block[i] = 0;
74 }
75 }
76 }