date and time created 90/05/15 14:01:13 by bostic

[unix-history] / usr / src / lib / libc / string / bcopy.c

/*
* Copyright (c) 1987, 1989 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     5.6 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>

/*
* bcopy -- copy memory block, handling overlap of source and destination
*      (vax movc3 instruction)
*/

typedef int word;               /* size of "word" used for optimal copy speed */

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) & (sizeof(word) - 1))
                               do      /* copy by bytes */
                                       *dst++ = *src++;
                               while (--length);
                       else {
                               length /= sizeof(word);
                               do {    /* copy by words */
                                       *(word *)dst = *(word *)src;
                                       src += sizeof(word);
                                       dst += sizeof(word);
                               } while (--length);
                       }
               else {                  /* copy backwards */
                       src += length;
                       dst += length;
                       if (((int)src | (int)dst | length) & (sizeof(word) - 1))
                               do      /* copy by bytes */
                                       *--dst = *--src;
                               while (--length);
                       else {
                               length /= sizeof(word);
                               do {    /* copy by words */
                                       src -= sizeof(word);
                                       dst -= sizeof(word);
                                       *(word *)dst = *(word *)src;
                               } while (--length);
                       }
               }
}