Annotation of sys/lib/libkern/memset.c, Revision 1.1.1.1
1.1 nbrk 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: }
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