2 * SPDX-License-Identifier: BSD-3-Clause
3 * Copyright (c) 1990 The Regents of the University of California.
7 * This code is derived from software contributed to Berkeley by
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11 * modification, are permitted provided that the following conditions
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35 #include <sys/param.h>
37 #include <sys/systm.h>
46 * sizeof(word) MUST BE A POWER OF TWO
47 * SO THAT wmask BELOW IS ALL ONES
49 typedef long word; /* "word" used for optimal copy speed */
51 #define wsize sizeof(word)
52 #define wmask (wsize - 1)
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.
60 memcpy(void *dst0, const void *src0, size_t length)
69 if (length == 0 || dst == src) { /* nothing to do */
74 * Macros: loop-t-times; and loop-t-times, t>0
76 #define TLOOP(s) if (t) TLOOP1(s)
77 #define TLOOP1(s) do { s; } while (--t)
79 if ((unsigned long)dst < (unsigned long)src) {
83 t = (size_t)src; /* only need low bits */
85 if ((t | (uintptr_t)dst) & wmask) {
87 * Try to align operands. This cannot be done
88 * unless the low bits match.
90 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) {
93 t = wsize - (t & wmask);
97 TLOOP1(*dst++ = *src++);
100 * Copy whole words, then mop up any trailing bytes.
103 TLOOP(*(word *)dst = *(const word *)src; src += wsize;
106 TLOOP(*dst++ = *src++);
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).
117 if ((t | (uintptr_t)dst) & wmask) {
118 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) {
125 TLOOP1(*--dst = *--src);
128 TLOOP(src -= wsize; dst -= wsize;
129 *(word *)dst = *(const word *)src);
131 TLOOP(*--dst = *--src);
137 __strong_reference(memcpy, memmove);