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 typedef intptr_t word; /* "word" used for optimal copy speed */
44
45 #define wsize sizeof(word)
46 #define wmask (wsize - 1)
47
48 /*
49 * Copy a block of memory, handling overlap.
50 * This is the routine that actually implements
51 * (the portable versions of) bcopy, memcpy, and memmove.
52 */
53 #if defined(MEMCOPY) || defined(MEMMOVE)
54 #include <string.h>
55
56 void *
57 #ifdef MEMCOPY
memcpy(void * dst0,const void * src0,size_t length)58 memcpy
59 #else
60 memmove
61 #endif
62 (void *dst0, const void *src0, size_t length)
63 #else
64 #include <strings.h>
65
66 void
67 bcopy(const void *src0, void *dst0, size_t length)
68 #endif
69 {
70 char *dst = dst0;
71 const char *src = src0;
72 size_t t;
73
74 if (length == 0 || dst == src) /* nothing to do */
75 goto done;
76
77 /*
78 * Macros: loop-t-times; and loop-t-times, t>0
79 */
80 #define TLOOP(s) if (t) TLOOP1(s)
81 #define TLOOP1(s) do { s; } while (--t)
82
83 if ((unsigned long)dst < (unsigned long)src) {
84 /*
85 * Copy forward.
86 */
87 t = (uintptr_t)src; /* only need low bits */
88 if ((t | (uintptr_t)dst) & wmask) {
89 /*
90 * Try to align operands. This cannot be done
91 * unless the low bits match.
92 */
93 if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
94 t = length;
95 else
96 t = wsize - (t & wmask);
97 length -= t;
98 TLOOP1(*dst++ = *src++);
99 }
100 /*
101 * Copy whole words, then mop up any trailing bytes.
102 */
103 t = length / wsize;
104 TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src;
105 src += wsize; dst += wsize);
106 t = length & wmask;
107 TLOOP(*dst++ = *src++);
108 } else {
109 /*
110 * Copy backwards. Otherwise essentially the same.
111 * Alignment works as before, except that it takes
112 * (t&wmask) bytes to align, not wsize-(t&wmask).
113 */
114 src += length;
115 dst += length;
116 t = (uintptr_t)src;
117 if ((t | (uintptr_t)dst) & wmask) {
118 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
119 t = length;
120 else
121 t &= wmask;
122 length -= t;
123 TLOOP1(*--dst = *--src);
124 }
125 t = length / wsize;
126 TLOOP(src -= wsize; dst -= wsize;
127 *(word *)(void *)dst = *(const word *)(const void *)src);
128 t = length & wmask;
129 TLOOP(*--dst = *--src);
130 }
131 done:
132 #if defined(MEMCOPY) || defined(MEMMOVE)
133 return (dst0);
134 #else
135 return;
136 #endif
137 }
138