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