1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 * Copyright (c) 1990 The Regents of the University of California.
4 *
5 * 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 #include <sys/param.h>
36 #ifdef _KERNEL
37 #include <sys/systm.h>
38 #else
39 #include <string.h>
40 #endif
41
42 #undef memcpy
43 #undef memmove
44
45 /*
46 * sizeof(word) MUST BE A POWER OF TWO
47 * SO THAT wmask BELOW IS ALL ONES
48 */
49 typedef long word; /* "word" used for optimal copy speed */
50
51 #define wsize sizeof(word)
52 #define wmask (wsize - 1)
53
54 /*
55 * Copy a block of memory, handling overlap.
56 * This is the routine that actually implements
57 * (the portable versions of) bcopy, memcpy, and memmove.
58 */
59 void *
memcpy(void * dst0,const void * src0,size_t length)60 memcpy(void *dst0, const void *src0, size_t length)
61 {
62 char *dst;
63 const char *src;
64 size_t t;
65
66 dst = dst0;
67 src = src0;
68
69 if (length == 0 || dst == src) { /* nothing to do */
70 goto done;
71 }
72
73 /*
74 * Macros: loop-t-times; and loop-t-times, t>0
75 */
76 #define TLOOP(s) if (t) TLOOP1(s)
77 #define TLOOP1(s) do { s; } while (--t)
78
79 if ((unsigned long)dst < (unsigned long)src) {
80 /*
81 * Copy forward.
82 */
83 t = (size_t)src; /* only need low bits */
84
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 }
95
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 = *(const word *)src; src += wsize;
104 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
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 }
123
124 length -= t;
125 TLOOP1(*--dst = *--src);
126 }
127 t = length / wsize;
128 TLOOP(src -= wsize; dst -= wsize;
129 *(word *)dst = *(const word *)src);
130 t = length & wmask;
131 TLOOP(*--dst = *--src);
132 }
133 done:
134 return (dst0);
135 }
136
137 __strong_reference(memcpy, memmove);
138