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1.1 root 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: * 3. All advertising materials mentioning features or use of this software
17: * must display the following acknowledgement:
18: * This product includes software developed by the University of
19: * California, Berkeley and its contributors.
20: * 4. Neither the name of the University nor the names of its contributors
21: * may be used to endorse or promote products derived from this software
22: * without specific prior written permission.
23: *
24: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34: * SUCH DAMAGE.
35: */
36:
37: #if defined(LIBC_SCCS) && !defined(lint)
38: static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93";
39: #endif /* LIBC_SCCS and not lint */
40:
41: #include <sys/types.h>
42: #include "cdefs.h"
43: #include <string.h>
44:
45: /*
46: * sizeof(word) MUST BE A POWER OF TWO
47: * SO THAT wmask BELOW IS ALL ONES
48: */
49: typedef int word; /* "word" used for optimal copy speed */
50:
51: #define wsize sizeof(word)
52: #define wmask (wsize - 1)
53:
54: /*
55: * Copy a block of memory, handling overlap.
56: * This is the routine that actually implements
57: * (the portable versions of) bcopy, memcpy, and memmove.
58: */
59: void *
60: memmove(dst0, src0, length)
61: void *dst0;
62: const void *src0;
63: register size_t length;
64: {
65: register char *dst = dst0;
66: register const char *src = src0;
67: register size_t t;
68:
69: if (length == 0 || dst == src) /* nothing to do */
70: goto done;
71:
72: /*
73: * Macros: loop-t-times; and loop-t-times, t>0
74: */
75: #define TLOOP(s) if (t) TLOOP1(s)
76: #define TLOOP1(s) do { s; } while (--t)
77:
78: if ((unsigned long)dst < (unsigned long)src) {
79: /*
80: * Copy forward.
81: */
82: t = (int)src; /* only need low bits */
83: if ((t | (int)dst) & wmask) {
84: /*
85: * Try to align operands. This cannot be done
86: * unless the low bits match.
87: */
88: if ((t ^ (int)dst) & wmask || length < wsize)
89: t = length;
90: else
91: t = wsize - (t & wmask);
92: length -= t;
93: TLOOP1(*dst++ = *src++);
94: }
95: /*
96: * Copy whole words, then mop up any trailing bytes.
97: */
98: t = length / wsize;
99: TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
100: t = length & wmask;
101: TLOOP(*dst++ = *src++);
102: } else {
103: /*
104: * Copy backwards. Otherwise essentially the same.
105: * Alignment works as before, except that it takes
106: * (t&wmask) bytes to align, not wsize-(t&wmask).
107: */
108: src += length;
109: dst += length;
110: t = (int)src;
111: if ((t | (int)dst) & wmask) {
112: if ((t ^ (int)dst) & wmask || length <= wsize)
113: t = length;
114: else
115: t &= wmask;
116: length -= t;
117: TLOOP1(*--dst = *--src);
118: }
119: t = length / wsize;
120: TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
121: t = length & wmask;
122: TLOOP(*--dst = *--src);
123: }
124: done:
125: return (dst0);
126: }
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