1 /*-
2 * See the file LICENSE for redistribution information.
3 *
4 * Copyright (c) 1996, 2013 Oracle and/or its affiliates. All rights reserved.
5 */
6 /*
7 * Copyright (c) 1990, 1993
8 * The Regents of the University of California. All rights reserved.
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 * $Id$
35 */
36
37 #include "db_config.h"
38
39 #include "db_int.h"
40
41 /*
42 * sizeof(word) MUST BE A POWER OF TWO
43 * SO THAT wmask BELOW IS ALL ONES
44 */
45 typedef int word; /* "word" used for optimal copy speed */
46
47 #undef wsize
48 #define wsize sizeof(word)
49 #undef wmask
50 #define wmask (wsize - 1)
51
52 /*
53 * Copy a block of memory, handling overlap.
54 * This is the routine that actually implements
55 * (the portable versions of) bcopy, memcpy, and memmove.
56 */
57 #ifdef MEMCOPY
58 /*
59 * PUBLIC: #ifndef HAVE_MEMCPY
60 * PUBLIC: void *memcpy __P((void *, const void *, size_t));
61 * PUBLIC: #endif
62 */
63 void *
memcpy(dst0,src0,length)64 memcpy(dst0, src0, length)
65 #else
66 #ifdef MEMMOVE
67 /*
68 * PUBLIC: #ifndef HAVE_MEMMOVE
69 * PUBLIC: void *memmove __P((void *, const void *, size_t));
70 * PUBLIC: #endif
71 */
72 void *
73 memmove(dst0, src0, length)
74 #else
75 void
76 bcopy(src0, dst0, length)
77 #endif
78 #endif
79 void *dst0;
80 const void *src0;
81 register size_t length;
82 {
83 register char *dst = dst0;
84 register const char *src = src0;
85 register size_t t;
86
87 if (length == 0 || dst == src) /* nothing to do */
88 goto done;
89
90 /*
91 * Macros: loop-t-times; and loop-t-times, t>0
92 */
93 #undef TLOOP
94 #define TLOOP(s) if (t) TLOOP1(s)
95 #undef TLOOP1
96 #define TLOOP1(s) do { s; } while (--t)
97
98 if ((unsigned long)dst < (unsigned long)src) {
99 /*
100 * Copy forward.
101 */
102 t = (size_t)src; /* only need low bits */
103 if ((t | (size_t)dst) & wmask) {
104 /*
105 * Try to align operands. This cannot be done
106 * unless the low bits match.
107 */
108 if ((t ^ (size_t)dst) & wmask || length < wsize)
109 t = length;
110 else
111 t = wsize - (t & wmask);
112 length -= t;
113 TLOOP1(*dst++ = *src++);
114 }
115 /*
116 * Copy whole words, then mop up any trailing bytes.
117 */
118 t = length / wsize;
119 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
120 t = length & wmask;
121 TLOOP(*dst++ = *src++);
122 } else {
123 /*
124 * Copy backwards. Otherwise essentially the same.
125 * Alignment works as before, except that it takes
126 * (t&wmask) bytes to align, not wsize-(t&wmask).
127 */
128 src += length;
129 dst += length;
130 t = (size_t)src;
131 if ((t | (size_t)dst) & wmask) {
132 if ((t ^ (size_t)dst) & wmask || length <= wsize)
133 t = length;
134 else
135 t &= wmask;
136 length -= t;
137 TLOOP1(*--dst = *--src);
138 }
139 t = length / wsize;
140 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
141 t = length & wmask;
142 TLOOP(*--dst = *--src);
143 }
144 done:
145 #if defined(MEMCOPY) || defined(MEMMOVE)
146 return (dst0);
147 #else
148 return;
149 #endif
150 }
151