/*-

 * Copyright (c) 1990, 1993

 *	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. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *	This product includes software developed by the University of

 *	California, Berkeley and its contributors.

 * 4. 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)

static char sccsid[] = "@(#)bcopy.c	8.1 (Berkeley) 6/4/93";

#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>

#include <string.h>

#ifndef HAVE_BCOPY

void bcopy(const void *, void *, size_t);

#endif

/*

 * sizeof(word) MUST BE A POWER OF TWO

 * SO THAT wmask BELOW IS ALL ONES

 */

typedef	int 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.

 */

#ifdef MEMCOPY

void *

memcpy(dst0, src0, length)

#else

#ifdef MEMMOVE

void *

memmove(dst0, src0, length)

#else

void

bcopy(src0, dst0, length)

#endif

#endif

	void *dst0;

	const void *src0;

	register size_t length;

{

	register char *dst = dst0;

	register const char *src = src0;

	register size_t t;

	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 = (int)src;	/* only need low bits */

		if ((t | (int)dst) & wmask) {

			/*

			 * Try to align operands.  This cannot be done

			 * unless the low bits match.

			 */

			if ((t ^ (int)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 = *(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 = (int)src;

		if ((t | (int)dst) & wmask) {

			if ((t ^ (int)dst) & wmask || length <= wsize)

				t = length;

			else

				t &= wmask;

			length -= t;

			TLOOP1(*--dst = *--src);

		}

		t = length / wsize;

		TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);

		t = length & wmask;

		TLOOP(*--dst = *--src);

	}

done:

#if defined(MEMCOPY) || defined(MEMMOVE)

	return (dst0);

#else

	return;

#endif

}