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 * @(#)bcopy.c 8.1 (Berkeley) 6/4/93
33 * $FreeBSD: head/lib/libc/string/bcopy.c 251069 2013-05-28 20:57:40Z emaste $
34 */
35
36 #include <sys/types.h>
37
38 /*
39 * sizeof(word) MUST BE A POWER OF TWO
40 * SO THAT wmask BELOW IS ALL ONES
41 */
42 typedef int word; /* "word" used for optimal copy speed */
43
44 #define wsize sizeof(word)
45 #define wmask (wsize - 1)
46
47 /*
48 * Copy a block of memory, handling overlap.
49 * This is the routine that actually implements
50 * (the portable versions of) bcopy, memcpy, and memmove.
51 */
52 #if defined(MEMCOPY) || defined(MEMMOVE)
53 #include <string.h>
54
55 void *
56 #ifdef MEMCOPY
memcpy(void * dst0,const void * src0,size_t length)57 memcpy
58 #else
59 memmove
60 #endif
61 (void *dst0, const void *src0, size_t length)
62 #else
63 #include <strings.h>
64
65 void
66 bcopy(const void *src0, void *dst0, size_t length)
67 #endif
68 {
69 char *dst = dst0;
70 const char *src = src0;
71 size_t t;
72
73 if (length == 0 || dst == src) /* nothing to do */
74 goto done;
75
76 /*
77 * Macros: loop-t-times; and loop-t-times, t>0
78 */
79 #define TLOOP(s) if (t) TLOOP1(s)
80 #define TLOOP1(s) do { s; } while (--t)
81
82 if ((unsigned long)dst < (unsigned long)src) {
83 /*
84 * Copy forward.
85 */
86 t = (uintptr_t)src; /* only need low bits */
87 if ((t | (uintptr_t)dst) & wmask) {
88 /*
89 * Try to align operands. This cannot be done
90 * unless the low bits match.
91 */
92 if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
93 t = length;
94 else
95 t = wsize - (t & wmask);
96 length -= t;
97 TLOOP1(*dst++ = *src++);
98 }
99 /*
100 * Copy whole words, then mop up any trailing bytes.
101 */
102 t = length / wsize;
103 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
104 t = length & wmask;
105 TLOOP(*dst++ = *src++);
106 } else {
107 /*
108 * Copy backwards. Otherwise essentially the same.
109 * Alignment works as before, except that it takes
110 * (t&wmask) bytes to align, not wsize-(t&wmask).
111 */
112 src += length;
113 dst += length;
114 t = (uintptr_t)src;
115 if ((t | (uintptr_t)dst) & wmask) {
116 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
117 t = length;
118 else
119 t &= wmask;
120 length -= t;
121 TLOOP1(*--dst = *--src);
122 }
123 t = length / wsize;
124 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)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