usr/src/lib/libc/string/bcopy.c

/*
 * Copyright (c) 1987 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bcopy.c     5.2 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

/*
 * bcopy -- vax movc3 instruction
 */
bcopy(src, dst, length)
        register char *src, *dst;
        register int length;
{
        if (length && src != dst)
                if ((u_int)dst < (u_int)src)
                        if (((int)src | (int)dst | length) & 3)
                                do      /* copy by bytes */
                                        *dst++ = *src++;
                                while (--length);
                        else {
                                length >>= 2;
                                do      /* copy by longs */
                                        *((long *)dst)++ = *((long *)src)++;
                                while (--length);
                        }
                else {                  /* copy backwards */
                        src += length;
                        dst += length;
                        if (((int)src | (int)dst | length) & 3)
                                do      /* copy by bytes */
                                        *--dst = *--src;
                                while (--length);
                        else {
                                length >>= 2;
                                do      /* copy by shorts */
                                        *--((long *)dst) = *--((long *)src);
                                while (--length);
                        }
                }
        return(0);
}