Net2/usr/src/usr.sbin/timed/timed/cksum.vax.c

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * 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.
 */

#ifndef lint
static char sccsid[] = "@(#)cksum.vax.c	1.5 (Berkeley) 6/1/90";
#endif /* not lint */

#include <sys/types.h>

#define ADD	asm("adwc (r9)+,r8;");

/* computes the checksum for ip packets for the VAX */

in_cksum(addr, len)
u_short *addr;
int len;
{
	register int nleft = len;	/* on vax, (user mode), r11 */
#ifndef lint
	register int xxx;		/* on vax, (user mode), r10 */
#endif not lint
	register u_short *w = addr;	/* on vax, known to be r9 */
	register int sum = 0;		/* on vax, known to be r8 */

	if (((int)w&0x2) && nleft >= 2) {
		sum += *w++;
		nleft -= 2;
	}
	while ((nleft -= 32) >= 0) {
		asm("clrl r0");		/* clears carry */
		ADD; ADD; ADD; ADD; ADD; ADD; ADD; ADD;
		asm("adwc $0,r8");
	}
	nleft += 32;
	while ((nleft -= 8) >= 0) {
		asm("clrl r0");
		ADD; ADD;
		asm("adwc $0,r8");
	}
	nleft += 8;
	{ asm("ashl $-16,r8,r0; addw2 r0,r8");
	  asm("adwc $0,r8; movzwl r8,r8"); }
	while ((nleft -= 2) >= 0) {
		asm("movzwl (r9)+,r0; addl2 r0,r8");
	}
	if (nleft == -1) {
		sum += *(u_char *)w;
	}

	{ asm("ashl $-16,r8,r0; addw2 r0,r8; adwc $0,r8");
	  asm("mcoml r8,r8; movzwl r8,r8"); }
	return (sum);
}