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 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35
36 #include <stdint.h>
37 #include <sys/types.h>
38
39 /*
40 * sizeof(word) MUST BE A POWER OF TWO
41 * SO THAT wmask BELOW IS ALL ONES
42 */
43 typedef int 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 *)dst = *(word *)src; src += wsize; dst += wsize);
105 t = length & wmask;
106 TLOOP(*dst++ = *src++);
107 } else {
108 /*
109 * Copy backwards. Otherwise essentially the same.
110 * Alignment works as before, except that it takes
111 * (t&wmask) bytes to align, not wsize-(t&wmask).
112 */
113 src += length;
114 dst += length;
115 t = (uintptr_t)src;
116 if ((t | (uintptr_t)dst) & wmask) {
117 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
118 t = length;
119 else
120 t &= wmask;
121 length -= t;
122 TLOOP1(*--dst = *--src);
123 }
124 t = length / wsize;
125 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
126 t = length & wmask;
127 TLOOP(*--dst = *--src);
128 }
129 done:
130 #if defined(MEMCOPY) || defined(MEMMOVE)
131 return (dst0);
132 #else
133 return;
134 #endif
135 }
136