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
37typedef	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 * This is the routine that actually implements
45 * (the portable versions of) bcopy, memcpy, and memmove.
46 */
47#if defined(MEMCOPY) || defined(MEMMOVE)
48#include <string.h>
49
50#undef memcpy	/* _FORTIFY_SOURCE */
51#undef memmove	/* _FORTIFY_SOURCE */
52
53void *
54#ifdef MEMCOPY
55memcpy
56#else
57memmove
58#endif
59(void *dst0, const void *src0, size_t length)
60#else
61#include <strings.h>
62
63#undef bcopy	/* _FORTIFY_SOURCE */
64
65void
66bcopy(const void *src0, void *dst0, size_t length)
67#endif
68{
69	char *dst = dst0;
70	const char *src = src0;
71	size_t t;
72
73	if (length == 0 || dst == src)		/* nothing to do */
74		goto done;
75
76	/*
77	 * Macros: loop-t-times; and loop-t-times, t>0
78	 */
79#define	TLOOP(s) if (t) TLOOP1(s)
80#define	TLOOP1(s) do { s; } while (--t)
81
82	if ((unsigned long)dst < (unsigned long)src) {
83		/*
84		 * Copy forward.
85		 */
86		t = (uintptr_t)src;	/* only need low bits */
87		if ((t | (uintptr_t)dst) & wmask) {
88			/*
89			 * Try to align operands.  This cannot be done
90			 * unless the low bits match.
91			 */
92			if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
93				t = length;
94			else
95				t = wsize - (t & wmask);
96			length -= t;
97			TLOOP1(*dst++ = *src++);
98		}
99		/*
100		 * Copy whole words, then mop up any trailing bytes.
101		 */
102		t = length / wsize;
103		TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src;
104		    src += wsize; dst += wsize);
105		t = length & wmask;
106		TLOOP(*dst++ = *src++);
107	} else {
108		/*
109		 * Copy backwards.  Otherwise essentially the same.
110		 * Alignment works as before, except that it takes
111		 * (t&wmask) bytes to align, not wsize-(t&wmask).
112		 */
113		src += length;
114		dst += length;
115		t = (uintptr_t)src;
116		if ((t | (uintptr_t)dst) & wmask) {
117			if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
118				t = length;
119			else
120				t &= wmask;
121			length -= t;
122			TLOOP1(*--dst = *--src);
123		}
124		t = length / wsize;
125		TLOOP(src -= wsize; dst -= wsize;
126		    *(word *)(void *)dst = *(const word *)(const void *)src);
127		t = length & wmask;
128		TLOOP(*--dst = *--src);
129	}
130done:
131#if defined(MEMCOPY) || defined(MEMMOVE)
132	return (dst0);
133#else
134	return;
135#endif
136}
137