1 /*-
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. 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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93";
35 #endif /* LIBC_SCCS and not lint */
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38
39 #include <sys/types.h>
40
41 /*
42 * sizeof(word) MUST BE A POWER OF TWO
43 * SO THAT wmask BELOW IS ALL ONES
44 */
45 typedef int word; /* "word" used for optimal copy speed */
46
47 #define wsize sizeof(word)
48 #define wmask (wsize - 1)
49
50 /*
51 * Copy a block of memory, handling overlap.
52 * This is the routine that actually implements
53 * (the portable versions of) bcopy, memcpy, and memmove.
54 */
55 #if defined(MEMCOPY) || defined(MEMMOVE)
56 #include <string.h>
57
58 void *
59 #ifdef MEMCOPY
memcpy(void * dst0,const void * src0,size_t length)60 memcpy
61 #else
62 memmove
63 #endif
64 (void *dst0, const void *src0, size_t length)
65 #else
66 #include <strings.h>
67
68 void
69 bcopy(const void *src0, void *dst0, size_t length)
70 #endif
71 {
72 char *dst = dst0;
73 const char *src = src0;
74 size_t t;
75
76 if (length == 0 || dst == src) /* nothing to do */
77 goto done;
78
79 /*
80 * Macros: loop-t-times; and loop-t-times, t>0
81 */
82 #define TLOOP(s) if (t) TLOOP1(s)
83 #define TLOOP1(s) do { s; } while (--t)
84
85 if ((unsigned long)dst < (unsigned long)src) {
86 /*
87 * Copy forward.
88 */
89 t = (uintptr_t)src; /* only need low bits */
90 if ((t | (uintptr_t)dst) & wmask) {
91 /*
92 * Try to align operands. This cannot be done
93 * unless the low bits match.
94 */
95 if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
96 t = length;
97 else
98 t = wsize - (t & wmask);
99 length -= t;
100 TLOOP1(*dst++ = *src++);
101 }
102 /*
103 * Copy whole words, then mop up any trailing bytes.
104 */
105 t = length / wsize;
106 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
107 t = length & wmask;
108 TLOOP(*dst++ = *src++);
109 } else {
110 /*
111 * Copy backwards. Otherwise essentially the same.
112 * Alignment works as before, except that it takes
113 * (t&wmask) bytes to align, not wsize-(t&wmask).
114 */
115 src += length;
116 dst += length;
117 t = (uintptr_t)src;
118 if ((t | (uintptr_t)dst) & wmask) {
119 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
120 t = length;
121 else
122 t &= wmask;
123 length -= t;
124 TLOOP1(*--dst = *--src);
125 }
126 t = length / wsize;
127 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)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