1 /* $Id: bcopy.c,v 1.4 2020-09-27 22:06:16 phil Exp $ */
2
3 /*-
4 * Copyright (c) 1990 The Regents of the University of California.
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. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39 #ifdef HAVE_CONFIG_H
40 #include "config.h"
41 #endif /* HAVE_CONFIG_H defined */
42
43 #if defined(LIBC_SCCS) && !defined(lint)
44 static char sccsid[] = "@(#)bcopy.c 5.11 (Berkeley) 6/21/91";
45 #endif /* LIBC_SCCS and not lint */
46
47 #if 0
48 #include <sys/cdefs.h>
49 #include <string.h>
50 #else
51
52 #include "h.h"
53 typedef int size_t;
54 #endif
55
56
57 /*
58 * sizeof(word) MUST BE A POWER OF TWO
59 * SO THAT wmask BELOW IS ALL ONES
60 */
61 typedef int 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 #ifdef MEMCOPY
72 void *
memcpy(void * dst0,const void * src0,register size_t length)73 memcpy(void *dst0, const void *src0, register size_t length)
74 #else
75 #ifdef MEMMOVE
76 void *
77 memmove(void *dst0, const void *src0, register size_t length)
78 #else
79 void
80 bcopy(const void *src0, void *dst0, register size_t length)
81 #endif
82 #endif
83 {
84 register char *dst = dst0;
85 register const char *src = src0;
86 register size_t t;
87
88 if (length == 0 || dst == src) /* nothing to do */
89 goto done;
90
91 /*
92 * Macros: loop-t-times; and loop-t-times, t>0
93 */
94 #define TLOOP(s) if (t) TLOOP1(s)
95 #define TLOOP1(s) do { s; } while (--t)
96
97 if ((unsigned long)dst < (unsigned long)src) {
98 /*
99 * Copy forward.
100 */
101 t = (long)src; /* only need low bits */
102 if ((t | (long)dst) & wmask) {
103 /*
104 * Try to align operands. This cannot be done
105 * unless the low bits match.
106 */
107 if ((t ^ (long)dst) & wmask || length < wsize)
108 t = length;
109 else
110 t = wsize - (t & wmask);
111 length -= t;
112 TLOOP1(*dst++ = *src++);
113 }
114 /*
115 * Copy whole words, then mop up any trailing bytes.
116 */
117 t = length / wsize;
118 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
119 t = length & wmask;
120 TLOOP(*dst++ = *src++);
121 } else {
122 /*
123 * Copy backwards. Otherwise essentially the same.
124 * Alignment works as before, except that it takes
125 * (t&wmask) bytes to align, not wsize-(t&wmask).
126 */
127 src += length;
128 dst += length;
129 t = (long)src;
130 if ((t | (long)dst) & wmask) {
131 if ((t ^ (long)dst) & wmask || length <= wsize)
132 t = length;
133 else
134 t &= wmask;
135 length -= t;
136 TLOOP1(*--dst = *--src);
137 }
138 t = length / wsize;
139 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
140 t = length & wmask;
141 TLOOP(*--dst = *--src);
142 }
143 done:
144 #if defined(MEMCOPY) || defined(MEMMOVE)
145 return (dst0);
146 #else
147 return;
148 #endif
149 }
150