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/types.h>
39
40 typedef intptr_t word; /* "word" used for optimal copy speed */
41
42 #define wsize sizeof(word)
43 #define wmask (wsize - 1)
44
45 /*
46 * Copy a block of memory, handling overlap.
47 * This is the routine that actually implements
48 * (the portable versions of) bcopy, memcpy, and memmove.
49 */
50 #if defined(MEMCOPY) || defined(MEMMOVE)
51 #include <string.h>
52
53 void *
54 #ifdef MEMCOPY
memcpy(void * dst0,const void * src0,size_t length)55 memcpy
56 #else
57 memmove
58 #endif
59 (void *dst0, const void *src0, size_t length)
60 #else
61 #include <strings.h>
62
63 void
64 bcopy(const void *src0, void *dst0, size_t length)
65 #endif
66 {
67 char *dst = dst0;
68 const char *src = src0;
69 size_t t;
70
71 if (length == 0 || dst == src) /* nothing to do */
72 goto done;
73
74 /*
75 * Macros: loop-t-times; and loop-t-times, t>0
76 */
77 #define TLOOP(s) if (t) TLOOP1(s)
78 #define TLOOP1(s) do { s; } while (--t)
79
80 if ((unsigned long)dst < (unsigned long)src) {
81 /*
82 * Copy forward.
83 */
84 t = (uintptr_t)src; /* only need low bits */
85 if ((t | (uintptr_t)dst) & wmask) {
86 /*
87 * Try to align operands. This cannot be done
88 * unless the low bits match.
89 */
90 if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
91 t = length;
92 else
93 t = wsize - (t & wmask);
94 length -= t;
95 TLOOP1(*dst++ = *src++);
96 }
97 /*
98 * Copy whole words, then mop up any trailing bytes.
99 */
100 t = length / wsize;
101 TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src;
102 src += wsize; dst += wsize);
103 t = length & wmask;
104 TLOOP(*dst++ = *src++);
105 } else {
106 /*
107 * Copy backwards. Otherwise essentially the same.
108 * Alignment works as before, except that it takes
109 * (t&wmask) bytes to align, not wsize-(t&wmask).
110 */
111 src += length;
112 dst += length;
113 t = (uintptr_t)src;
114 if ((t | (uintptr_t)dst) & wmask) {
115 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
116 t = length;
117 else
118 t &= wmask;
119 length -= t;
120 TLOOP1(*--dst = *--src);
121 }
122 t = length / wsize;
123 TLOOP(src -= wsize; dst -= wsize;
124 *(word *)(void *)dst = *(const word *)(const void *)src);
125 t = length & wmask;
126 TLOOP(*--dst = *--src);
127 }
128 done:
129 #if defined(MEMCOPY) || defined(MEMMOVE)
130 return (dst0);
131 #else
132 return;
133 #endif
134 }
135