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 #if defined(LIBC_SCCS) && !defined(lint)
36 #if 0
37 static char *sccsid = "from: @(#)bcopy.c 5.11 (Berkeley) 6/21/91";
38 #endif
39 #if 0
40 static char *rcsid = "$NetBSD: bcopy.c,v 1.2 1997/04/16 22:09:41 thorpej Exp $";
41 #endif
42 #endif /* LIBC_SCCS and not lint */
43 #include <sys/cdefs.h>
44 #include <sys/param.h>
45 #ifdef _KERNEL
46 #include <sys/systm.h>
47 #else
48 #include <string.h>
49 #endif
50
51 #undef memcpy
52 #undef memmove
53
54 /*
55 * sizeof(word) MUST BE A POWER OF TWO
56 * SO THAT wmask BELOW IS ALL ONES
57 */
58 typedef long word; /* "word" used for optimal copy speed */
59
60 #define wsize sizeof(word)
61 #define wmask (wsize - 1)
62
63 /*
64 * Copy a block of memory, handling overlap.
65 * This is the routine that actually implements
66 * (the portable versions of) bcopy, memcpy, and memmove.
67 */
68 void *
memcpy(void * dst0,const void * src0,size_t length)69 memcpy(void *dst0, const void *src0, size_t length)
70 {
71 char *dst;
72 const char *src;
73 size_t t;
74
75 dst = dst0;
76 src = src0;
77
78 if (length == 0 || dst == src) { /* nothing to do */
79 goto done;
80 }
81
82 /*
83 * Macros: loop-t-times; and loop-t-times, t>0
84 */
85 #define TLOOP(s) if (t) TLOOP1(s)
86 #define TLOOP1(s) do { s; } while (--t)
87
88 if ((unsigned long)dst < (unsigned long)src) {
89 /*
90 * Copy forward.
91 */
92 t = (size_t)src; /* only need low bits */
93
94 if ((t | (uintptr_t)dst) & wmask) {
95 /*
96 * Try to align operands. This cannot be done
97 * unless the low bits match.
98 */
99 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) {
100 t = length;
101 } else {
102 t = wsize - (t & wmask);
103 }
104
105 length -= t;
106 TLOOP1(*dst++ = *src++);
107 }
108 /*
109 * Copy whole words, then mop up any trailing bytes.
110 */
111 t = length / wsize;
112 TLOOP(*(word *)dst = *(const word *)src; src += wsize;
113 dst += wsize);
114 t = length & wmask;
115 TLOOP(*dst++ = *src++);
116 } else {
117 /*
118 * Copy backwards. Otherwise essentially the same.
119 * Alignment works as before, except that it takes
120 * (t&wmask) bytes to align, not wsize-(t&wmask).
121 */
122 src += length;
123 dst += length;
124 t = (uintptr_t)src;
125
126 if ((t | (uintptr_t)dst) & wmask) {
127 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) {
128 t = length;
129 } else {
130 t &= wmask;
131 }
132
133 length -= t;
134 TLOOP1(*--dst = *--src);
135 }
136 t = length / wsize;
137 TLOOP(src -= wsize; dst -= wsize;
138 *(word *)dst = *(const word *)src);
139 t = length & wmask;
140 TLOOP(*--dst = *--src);
141 }
142 done:
143 return (dst0);
144 }
145
146 __strong_reference(memcpy, memmove);
147