/*-
 * Copyright (c) 2007
 *	Thorsten Glaser <tg@mirbsd.de>
 *
 * Provided that these terms and disclaimer and all copyright notices
 * are retained or reproduced in an accompanying document, permission
 * is granted to deal in this work without restriction, including un-
 * limited rights to use, publicly perform, distribute, sell, modify,
 * merge, give away, or sublicence.
 *
 * This work is provided "AS IS" and WITHOUT WARRANTY of any kind, to
 * the utmost extent permitted by applicable law, neither express nor
 * implied; without malicious intent or gross negligence. In no event
 * may a licensor, author or contributor be held liable for indirect,
 * direct, other damage, loss, or other issues arising in any way out
 * of dealing in the work, even if advised of the possibility of such
 * damage or existence of a defect, except proven that it results out
 * of said person's immediate fault when using the work as intended.
 */

#include <stdint.h>
#include <string.h>

__RCSID("$MirOS: src/lib/libc/string/bcopy.c,v 1.8 2007/08/08 20:57:41 tg Exp $");

/* this is the basic copy data type, should be fastest */
typedef unsigned long mword;

#define mbytes	sizeof (mword)
#define mmask	(mbytes - 1)

#ifdef MEMCOPY
#define MEMMOVE
#define memmove	memcpy
#endif

#ifdef MEMMOVE
void *
memmove(void *dst, const void *src, size_t len)
#else
void
bcopy(const void *src, void *dst, size_t len)
#endif
{
	const uint8_t *s = src;
	uint8_t *d = dst;
	size_t n;
	intptr_t cp;

	if (len == 0 || dst == src)
		goto done;

	if ((intptr_t)dst < (intptr_t)src) {
		/* copy forward */
		if ((((cp = (intptr_t)s) | (intptr_t)d) & mmask) &&
		    (((cp ^ (intptr_t)d) & mmask) == 0) && len >= mbytes) {
			/* low bits match: first align then copy entire words */
			n = mbytes - (cp & mmask);
			len -= n;
			while (n--)
				*d++ = *s++;
			n = len / mbytes;
			len &= mmask;
			while (n--) {
				*(mword *)d = *(const mword *)s;
				s += mbytes;
				d += mbytes;
			}
		}
		while (len--)
			*d++ = *s++;
	} else {
		/* copy backward */
		s += len;
		d += len;
		if ((((cp = (intptr_t)s) | (intptr_t)d) & mmask) &&
		    (((cp ^ (intptr_t)d) & mmask) == 0) && len >= mbytes) {
			/* low bits match: first align then copy entire words */
			n = cp & mmask;
			len -= n;
			while (n--)
				*--d = *--s;
			n = len / mbytes;
			len &= mmask;
			while (n--) {
				s -= mbytes;
				d -= mbytes;
				*(mword *)d = *(const mword *)s;
			}
		}
		while (len--)
			*--d = *--s;
	}
 done:
#ifdef MEMMOVE
	return (dst);
#else
	return;
#endif
}