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 * 4. 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 "string.h"
34
35 /*
36 * sizeof(word) MUST BE A POWER OF TWO
37 * SO THAT wmask BELOW IS ALL ONES
38 */
39 typedef int word; /* "word" used for optimal copy speed */
40
41 #define wsize sizeof(word)
42 #define wmask (wsize - 1)
43
44 /*
45 * Copy a block of memory, handling overlap.
46 * This is the routine that actually implements
47 * (the portable versions of) bcopy, memcpy, and memmove.
48 */
49
50 __attribute__((visibility("hidden")))
51 void *
_libkernel_memmove(void * dst0,const void * src0,size_t length)52 _libkernel_memmove(void *dst0, const void *src0, size_t length)
53 {
54 char *dst = dst0;
55 const char *src = src0;
56 size_t t;
57
58 if (length == 0 || dst == src) { /* nothing to do */
59 goto done;
60 }
61
62 /*
63 * Macros: loop-t-times; and loop-t-times, t>0
64 */
65 #define TLOOP(s) if (t) TLOOP1(s)
66 #define TLOOP1(s) do { s; } while (--t)
67
68 if ((unsigned long)dst < (unsigned long)src) {
69 /*
70 * Copy forward.
71 */
72 t = (uintptr_t)src; /* only need low bits */
73 if ((t | (uintptr_t)dst) & wmask) {
74 /*
75 * Try to align operands. This cannot be done
76 * unless the low bits match.
77 */
78 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) {
79 t = length;
80 } else {
81 t = wsize - (t & wmask);
82 }
83 length -= t;
84 TLOOP1(*dst++ = *src++);
85 }
86 /*
87 * Copy whole words, then mop up any trailing bytes.
88 */
89 t = length / wsize;
90 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
91 t = length & wmask;
92 TLOOP(*dst++ = *src++);
93 } else {
94 /*
95 * Copy backwards. Otherwise essentially the same.
96 * Alignment works as before, except that it takes
97 * (t&wmask) bytes to align, not wsize-(t&wmask).
98 */
99 src += length;
100 dst += length;
101 t = (uintptr_t)src;
102 if ((t | (uintptr_t)dst) & wmask) {
103 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) {
104 t = length;
105 } else {
106 t &= wmask;
107 }
108 length -= t;
109 TLOOP1(*--dst = *--src);
110 }
111 t = length / wsize;
112 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
113 t = length & wmask;
114 TLOOP(*--dst = *--src);
115 }
116 done:
117 return dst0;
118 }
119
120 __attribute__((visibility("hidden")))
121 void
bcopy(const void * s1,void * s2,size_t n)122 bcopy(const void *s1, void *s2, size_t n)
123 {
124 memcpy(s2, s1, n);
125 }
126