FreeBSD/Linux Kernel Cross Reference
sys/libkern/bcopy.c
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 $";
41 #endif
42 #endif /* LIBC_SCCS and not lint */
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD: releng/12.0/sys/libkern/bcopy.c 333444 2018-05-10 02:31:48Z imp $");
45
46 #include <sys/param.h>
47 #ifdef _KERNEL
48 #include <sys/systm.h>
49 #else
50 #include <string.h>
51 #endif
52
53 #undef memcpy
54 #undef memmove
55 #undef bcopy
56
57 /*
58 * sizeof(word) MUST BE A POWER OF TWO
59 * SO THAT wmask BELOW IS ALL ONES
60 */
61 typedef long word; /* "word" used for optimal copy speed */
62
63 #define wsize sizeof(word)
64 #define wmask (wsize - 1)
65
66 /*
67 * Copy a block of memory, handling overlap.
68 * This is the routine that actually implements
69 * (the portable versions of) bcopy, memcpy, and memmove.
70 */
71 void *
72 memcpy(void *dst0, const void *src0, size_t length)
73 {
74 char *dst;
75 const char *src;
76 size_t t;
77
78 dst = dst0;
79 src = src0;
80
81 if (length == 0 || dst == src) { /* nothing to do */
82 goto done;
83 }
84
85 /*
86 * Macros: loop-t-times; and loop-t-times, t>0
87 */
88 #define TLOOP(s) if (t) TLOOP1(s)
89 #define TLOOP1(s) do { s; } while (--t)
90
91 if ((unsigned long)dst < (unsigned long)src) {
92 /*
93 * Copy forward.
94 */
95 t = (size_t)src; /* only need low bits */
96
97 if ((t | (uintptr_t)dst) & wmask) {
98 /*
99 * Try to align operands. This cannot be done
100 * unless the low bits match.
101 */
102 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) {
103 t = length;
104 } else {
105 t = wsize - (t & wmask);
106 }
107
108 length -= t;
109 TLOOP1(*dst++ = *src++);
110 }
111 /*
112 * Copy whole words, then mop up any trailing bytes.
113 */
114 t = length / wsize;
115 TLOOP(*(word *)dst = *(const word *)src; src += wsize;
116 dst += wsize);
117 t = length & wmask;
118 TLOOP(*dst++ = *src++);
119 } else {
120 /*
121 * Copy backwards. Otherwise essentially the same.
122 * Alignment works as before, except that it takes
123 * (t&wmask) bytes to align, not wsize-(t&wmask).
124 */
125 src += length;
126 dst += length;
127 t = (uintptr_t)src;
128
129 if ((t | (uintptr_t)dst) & wmask) {
130 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) {
131 t = length;
132 } else {
133 t &= wmask;
134 }
135
136 length -= t;
137 TLOOP1(*--dst = *--src);
138 }
139 t = length / wsize;
140 TLOOP(src -= wsize; dst -= wsize;
141 *(word *)dst = *(const word *)src);
142 t = length & wmask;
143 TLOOP(*--dst = *--src);
144 }
145 done:
146 return (dst0);
147 }
148
149 __strong_reference(memcpy, memmove);
150
151 void
152 (bcopy)(const void *src0, void *dst0, size_t length)
153 {
154
155 memcpy(dst0, src0, length);
156 }
157
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