1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40
41 #include <sys/types.h>
42
43 /*
44 * sizeof(word) MUST BE A POWER OF TWO
45 * SO THAT wmask BELOW IS ALL ONES
46 */
47 typedef int word; /* "word" used for optimal copy speed */
48
49 #define wsize sizeof(word)
50 #define wmask (wsize - 1)
51
52 /*
53 * Copy a block of memory, handling overlap.
54 * This is the routine that actually implements
55 * (the portable versions of) bcopy, memcpy, and memmove.
56 */
57 #if defined(MEMCOPY) || defined(MEMMOVE)
58 #include <string.h>
59
60 void *
61 #ifdef MEMCOPY
memcpy(void * dst0,const void * src0,size_t length)62 memcpy
63 #else
64 memmove
65 #endif
66 (void *dst0, const void *src0, size_t length)
67 #else
68 #include <strings.h>
69
70 void
71 bcopy(const void *src0, void *dst0, size_t length)
72 #endif
73 {
74 char *dst = dst0;
75 const char *src = src0;
76 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 = (uintptr_t)src; /* only need low bits */
92 if ((t | (uintptr_t)dst) & wmask) {
93 /*
94 * Try to align operands. This cannot be done
95 * unless the low bits match.
96 */
97 if ((t ^ (uintptr_t)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 = (uintptr_t)src;
120 if ((t | (uintptr_t)dst) & wmask) {
121 if ((t ^ (uintptr_t)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 }
133 done:
134 #if defined(MEMCOPY) || defined(MEMMOVE)
135 return (dst0);
136 #else
137 return;
138 #endif
139 }
140