1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. 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/types.h>
36
37 typedef intptr_t word; /* "word" used for optimal copy speed */
38
39 #define wsize sizeof(word)
40 #define wmask (wsize - 1)
41
42 /*
43 * Copy a block of memory, handling overlap.
44 */
45 #include <string.h>
46
47 void *
48 #ifdef MEMCOPY
memcpy_gc(void * dst0,const void * src0,size_t length)49 memcpy_gc
50 #else
51 memmove_gc
52 #endif
53 (void *dst0, const void *src0, size_t length)
54 {
55 char *dst = dst0;
56 const char *src = src0;
57 size_t t;
58
59 if (length == 0 || dst == src) /* nothing to do */
60 goto done;
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 length -= t;
83 TLOOP1(*dst++ = *src++);
84 }
85 /*
86 * Copy whole words, then mop up any trailing bytes.
87 */
88 t = length / wsize;
89 TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src;
90 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 length -= t;
108 TLOOP1(*--dst = *--src);
109 }
110 t = length / wsize;
111 TLOOP(src -= wsize; dst -= wsize;
112 *(word *)(void *)dst = *(const word *)(const void *)src);
113 t = length & wmask;
114 TLOOP(*--dst = *--src);
115 }
116 done:
117 #if defined(MEMCOPY) || defined(MEMMOVE)
118 return (dst0);
119 #else
120 return;
121 #endif
122 }
123