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. 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#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)bcopy.c	8.1 (Berkeley) 6/4/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD$");
38
39#include <sys/types.h>
40
41/*
42 * sizeof(word) MUST BE A POWER OF TWO
43 * SO THAT wmask BELOW IS ALL ONES
44 */
45typedef	int word;		/* "word" used for optimal copy speed */
46
47#define	wsize	sizeof(word)
48#define	wmask	(wsize - 1)
49
50/*
51 * Copy a block of memory, handling overlap.
52 * This is the routine that actually implements
53 * (the portable versions of) bcopy, memcpy, and memmove.
54 */
55#if defined(MEMCOPY) || defined(MEMMOVE)
56#include <string.h>
57
58void *
59#ifdef MEMCOPY
60memcpy
61#else
62memmove
63#endif
64(void *dst0, const void *src0, size_t length)
65#else
66#include <strings.h>
67
68void
69bcopy(const void *src0, void *dst0, size_t length)
70#endif
71{
72	char *dst = dst0;
73	const char *src = src0;
74	size_t t;
75
76	if (length == 0 || dst == src)		/* nothing to do */
77		goto done;
78
79	/*
80	 * Macros: loop-t-times; and loop-t-times, t>0
81	 */
82#define	TLOOP(s) if (t) TLOOP1(s)
83#define	TLOOP1(s) do { s; } while (--t)
84
85	if ((unsigned long)dst < (unsigned long)src) {
86		/*
87		 * Copy forward.
88		 */
89		t = (uintptr_t)src;	/* only need low bits */
90		if ((t | (uintptr_t)dst) & wmask) {
91			/*
92			 * Try to align operands.  This cannot be done
93			 * unless the low bits match.
94			 */
95			if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
96				t = length;
97			else
98				t = wsize - (t & wmask);
99			length -= t;
100			TLOOP1(*dst++ = *src++);
101		}
102		/*
103		 * Copy whole words, then mop up any trailing bytes.
104		 */
105		t = length / wsize;
106		TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
107		t = length & wmask;
108		TLOOP(*dst++ = *src++);
109	} else {
110		/*
111		 * Copy backwards.  Otherwise essentially the same.
112		 * Alignment works as before, except that it takes
113		 * (t&wmask) bytes to align, not wsize-(t&wmask).
114		 */
115		src += length;
116		dst += length;
117		t = (uintptr_t)src;
118		if ((t | (uintptr_t)dst) & wmask) {
119			if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
120				t = length;
121			else
122				t &= wmask;
123			length -= t;
124			TLOOP1(*--dst = *--src);
125		}
126		t = length / wsize;
127		TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
128		t = length & wmask;
129		TLOOP(*--dst = *--src);
130	}
131done:
132#if defined(MEMCOPY) || defined(MEMMOVE)
133	return (dst0);
134#else
135	return;
136#endif
137}
138