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authorderaadt <>1995-10-18 08:42:23 +0000
committerderaadt <>1995-10-18 08:42:23 +0000
commit0527d29da443886d92e9a418180c5b25a5f8d270 (patch)
tree86b3a64928451a669cefa27900e5884036b4e349 /src/lib/libc/string/bcopy.c
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initial import of NetBSD tree
Diffstat (limited to 'src/lib/libc/string/bcopy.c')
-rw-r--r--src/lib/libc/string/bcopy.c139
1 files changed, 139 insertions, 0 deletions
diff --git a/src/lib/libc/string/bcopy.c b/src/lib/libc/string/bcopy.c
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1/*-
2 * Copyright (c) 1990 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#if defined(LIBC_SCCS) && !defined(lint)
38/*static char *sccsid = "from: @(#)bcopy.c 5.11 (Berkeley) 6/21/91";*/
39static char *rcsid = "$Id: bcopy.c,v 1.1.1.1 1995/10/18 08:42:20 deraadt Exp $";
40#endif /* LIBC_SCCS and not lint */
41
42#include <string.h>
43
44/*
45 * sizeof(word) MUST BE A POWER OF TWO
46 * SO THAT wmask BELOW IS ALL ONES
47 */
48typedef long word; /* "word" used for optimal copy speed */
49
50#define wsize sizeof(word)
51#define wmask (wsize - 1)
52
53/*
54 * Copy a block of memory, handling overlap.
55 * This is the routine that actually implements
56 * (the portable versions of) bcopy, memcpy, and memmove.
57 */
58#ifdef MEMCOPY
59void *
60memcpy(dst0, src0, length)
61#else
62#ifdef MEMMOVE
63void *
64memmove(dst0, src0, length)
65#else
66void
67bcopy(src0, dst0, length)
68#endif
69#endif
70 void *dst0;
71 const void *src0;
72 register size_t length;
73{
74 register char *dst = dst0;
75 register const char *src = src0;
76 register size_t t;
77
78 if (length == 0 || dst == src) /* nothing to do */
79 goto done;
80
81 /*
82 * Macros: loop-t-times; and loop-t-times, t>0
83 */
84#define TLOOP(s) if (t) TLOOP1(s)
85#define TLOOP1(s) do { s; } while (--t)
86
87 if ((unsigned long)dst < (unsigned long)src) {
88 /*
89 * Copy forward.
90 */
91 t = (long)src; /* only need low bits */
92 if ((t | (long)dst) & wmask) {
93 /*
94 * Try to align operands. This cannot be done
95 * unless the low bits match.
96 */
97 if ((t ^ (long)dst) & wmask || length < wsize)
98 t = length;
99 else
100 t = wsize - (t & wmask);
101 length -= t;
102 TLOOP1(*dst++ = *src++);
103 }
104 /*
105 * Copy whole words, then mop up any trailing bytes.
106 */
107 t = length / wsize;
108 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
109 t = length & wmask;
110 TLOOP(*dst++ = *src++);
111 } else {
112 /*
113 * Copy backwards. Otherwise essentially the same.
114 * Alignment works as before, except that it takes
115 * (t&wmask) bytes to align, not wsize-(t&wmask).
116 */
117 src += length;
118 dst += length;
119 t = (long)src;
120 if ((t | (long)dst) & wmask) {
121 if ((t ^ (long)dst) & wmask || length <= wsize)
122 t = length;
123 else
124 t &= wmask;
125 length -= t;
126 TLOOP1(*--dst = *--src);
127 }
128 t = length / wsize;
129 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
130 t = length & wmask;
131 TLOOP(*--dst = *--src);
132 }
133done:
134#if defined(MEMCOPY) || defined(MEMMOVE)
135 return (dst0);
136#else
137 return;
138#endif
139}