2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990, 1993
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7 * This code is derived from software contributed to Berkeley by
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35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include <sys/types.h>
44 * sizeof(word) MUST BE A POWER OF TWO
45 * SO THAT wmask BELOW IS ALL ONES
47 typedef int word; /* "word" used for optimal copy speed */
49 #define wsize sizeof(word)
50 #define wmask (wsize - 1)
53 * Copy a block of memory, handling overlap.
54 * This is the routine that actually implements
55 * (the portable versions of) bcopy, memcpy, and memmove.
57 #if defined(MEMCOPY) || defined(MEMMOVE)
66 (void *dst0, const void *src0, size_t length)
71 bcopy(const void *src0, void *dst0, size_t length)
75 const char *src = src0;
78 if (length == 0 || dst == src) /* nothing to do */
82 * Macros: loop-t-times; and loop-t-times, t>0
84 #define TLOOP(s) if (t) TLOOP1(s)
85 #define TLOOP1(s) do { s; } while (--t)
87 if ((unsigned long)dst < (unsigned long)src) {
91 t = (uintptr_t)src; /* only need low bits */
92 if ((t | (uintptr_t)dst) & wmask) {
94 * Try to align operands. This cannot be done
95 * unless the low bits match.
97 if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
100 t = wsize - (t & wmask);
102 TLOOP1(*dst++ = *src++);
105 * Copy whole words, then mop up any trailing bytes.
108 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
110 TLOOP(*dst++ = *src++);
113 * Copy backwards. Otherwise essentially the same.
114 * Alignment works as before, except that it takes
115 * (t&wmask) bytes to align, not wsize-(t&wmask).
120 if ((t | (uintptr_t)dst) & wmask) {
121 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
126 TLOOP1(*--dst = *--src);
129 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
131 TLOOP(*--dst = *--src);
134 #if defined(MEMCOPY) || defined(MEMMOVE)