/*-
* SPDX-License-Identifier: BSD-3-Clause
* Copyright (c) 1990 The Regents of the University of California.
*
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char *sccsid = "from: @(#)bcopy.c 5.11 (Berkeley) 6/21/91";
#endif
#if 0
static char *rcsid = "$NetBSD: bcopy.c,v 1.2 1997/04/16 22:09:41 thorpej Exp $";
#endif
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
#include <sys/param.h>
#ifdef _KERNEL
#include <sys/systm.h>
#else
#include <string.h>
#endif
#undef memcpy
#undef memmove
/*
* sizeof(word) MUST BE A POWER OF TWO
* SO THAT wmask BELOW IS ALL ONES
*/
typedef long word; /* "word" used for optimal copy speed */
#define wsize sizeof(word)
#define wmask (wsize - 1)
/*
* Copy a block of memory, handling overlap.
* This is the routine that actually implements
* (the portable versions of) bcopy, memcpy, and memmove.
*/
void *
memcpy(void *dst0, const void *src0, size_t length)
{
char *dst;
const char *src;
size_t t;
dst = dst0;
src = src0;
if (length == 0 || dst == src) { /* nothing to do */
goto done;
}
/*
* Macros: loop-t-times; and loop-t-times, t>0
*/
#define TLOOP(s) if (t) TLOOP1(s)
#define TLOOP1(s) do { s; } while (--t)
if ((unsigned long)dst < (unsigned long)src) {
/*
* Copy forward.
*/
t = (size_t)src; /* only need low bits */
if ((t | (uintptr_t)dst) & wmask) {
/*
* Try to align operands. This cannot be done
* unless the low bits match.
*/
if ((t ^ (uintptr_t)dst) & wmask || length < wsize) {
t = length;
} else {
t = wsize - (t & wmask);
}
length -= t;
TLOOP1(*dst++ = *src++);
}
/*
* Copy whole words, then mop up any trailing bytes.
*/
t = length / wsize;
TLOOP(*(word *)dst = *(const word *)src; src += wsize;
dst += wsize);
t = length & wmask;
TLOOP(*dst++ = *src++);
} else {
/*
* Copy backwards. Otherwise essentially the same.
* Alignment works as before, except that it takes
* (t&wmask) bytes to align, not wsize-(t&wmask).
*/
src += length;
dst += length;
t = (uintptr_t)src;
if ((t | (uintptr_t)dst) & wmask) {
if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) {
t = length;
} else {
t &= wmask;
}
length -= t;
TLOOP1(*--dst = *--src);
}
t = length / wsize;
TLOOP(src -= wsize; dst -= wsize;
*(word *)dst = *(const word *)src);
t = length & wmask;
TLOOP(*--dst = *--src);
}
done:
return (dst0);
}
__strong_reference(memcpy, memmove);
plain