[unix-history] / usr / src / sys / i386 / i386 / in_cksum.c

/*-
 * Copyright (c) 1990, 1993
 *	The 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.
 *
 * from tahoe:	in_cksum.c	1.2	86/01/05
 *	@(#)in_cksum.c	8.1 (Berkeley) 6/11/93
 */

#include <sys/param.h>
#include <sys/mbuf.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>

/*
 * Checksum routine for Internet Protocol family headers.
 *
 * This routine is very heavily used in the network
 * code and should be modified for each CPU to be as fast as possible.
 * 
 * This implementation is 386 version.
 */

#undef	ADDCARRY
#define ADDCARRY(sum)  {				\
			if (sum & 0xffff0000) {		\
				sum &= 0xffff;		\
				sum++;			\
			}				\
		}
in_cksum(m, len)
	register struct mbuf *m;
	register int len;
{
	union word {
		char	c[2];
		u_short	s;
	} u;
	register u_short *w;
	register int sum = 0;
	register int mlen = 0;

	for (;m && len; m = m->m_next) {
		if (m->m_len == 0)
			continue;
		w = mtod(m, u_short *);
		if (mlen == -1) {
			/*
			 * The first byte of this mbuf is the continuation
			 * of a word spanning between this mbuf and the
			 * last mbuf.
			 */

			/* u.c[0] is already saved when scanning previous 
			 * mbuf.
			 */
			u.c[1] = *(u_char *)w;
			sum += u.s;
			ADDCARRY(sum);
			w = (u_short *)((char *)w + 1);
			mlen = m->m_len - 1;
			len--;
		} else
			mlen = m->m_len;

		if (len < mlen)
			mlen = len;
		len -= mlen;

		/*
		 * add by words.
		 */
		while ((mlen -= 2) >= 0) {
			if ((int)w & 0x1) {
				/* word is not aligned */
				u.c[0] = *(char *)w;
				u.c[1] = *((char *)w+1);
				sum += u.s;
				w++;
			} else
				sum += *w++;
			ADDCARRY(sum);
		}
		if (mlen == -1)
			/*
			 * This mbuf has odd number of bytes. 
			 * There could be a word split betwen
			 * this mbuf and the next mbuf.
			 * Save the last byte (to prepend to next mbuf).
			 */
			u.c[0] = *(u_char *)w;
	}
	if (len)
		printf("cksum: out of data\n");
	if (mlen == -1) {
		/* The last mbuf has odd # of bytes. Follow the
		   standard (the odd byte is shifted left by 8 bits) */
		u.c[1] = 0;
		sum += u.s;
		ADDCARRY(sum);
	}
	return (~sum & 0xffff);
}
Commit	Line	Data
3da89300	1	/*-
ad787160 C	2	* Copyright (c) 1990, 1993
ad787160 C	3	* The Regents of the University of California. All rights reserved.
3da89300	4	*
ad787160 C	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. All advertising materials mentioning features or use of this software
	14	* must display the following acknowledgement:
	15	* This product includes software developed by the University of
	16	* California, Berkeley and its contributors.
	17	* 4. Neither the name of the University nor the names of its contributors
	18	* may be used to endorse or promote products derived from this software
	19	* without specific prior written permission.
	20	*
	21	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	22	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	23	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	24	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	25	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	26	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	27	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	28	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	29	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	30	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	31	* SUCH DAMAGE.
3da89300 WN	32	*
3da89300 WN	33	* from tahoe: in_cksum.c 1.2 86/01/05
ad787160	34	* @(#)in_cksum.c 8.1 (Berkeley) 6/11/93
3da89300	35	*/
79189150	36
38a01dbe KB	37	#include <sys/param.h>
	38	#include <sys/mbuf.h>
	39
	40	#include <netinet/in.h>
	41	#include <netinet/in_systm.h>
79189150 BJ	42
	43	/*
	44	* Checksum routine for Internet Protocol family headers.
	45	*
	46	* This routine is very heavily used in the network
	47	* code and should be modified for each CPU to be as fast as possible.
	48	*
3da89300	49	* This implementation is 386 version.
79189150 BJ	50	*/
	51
	52	#undef ADDCARRY
	53	#define ADDCARRY(sum) { \
	54	if (sum & 0xffff0000) { \
	55	sum &= 0xffff; \
	56	sum++; \
	57	} \
	58	}
	59	in_cksum(m, len)
	60	register struct mbuf *m;
	61	register int len;
	62	{
	63	union word {
	64	char c[2];
	65	u_short s;
	66	} u;
	67	register u_short *w;
	68	register int sum = 0;
	69	register int mlen = 0;
	70
	71	for (;m && len; m = m->m_next) {
	72	if (m->m_len == 0)
	73	continue;
	74	w = mtod(m, u_short *);
	75	if (mlen == -1) {
	76	/*
	77	* The first byte of this mbuf is the continuation
	78	* of a word spanning between this mbuf and the
	79	* last mbuf.
	80	*/
	81
	82	/* u.c[0] is already saved when scanning previous
	83	* mbuf.
	84	*/
	85	u.c[1] = (u_char )w;
	86	sum += u.s;
	87	ADDCARRY(sum);
	88	w = (u_short )((char )w + 1);
	89	mlen = m->m_len - 1;
	90	len--;
	91	} else
	92	mlen = m->m_len;
	93
	94	if (len < mlen)
	95	mlen = len;
	96	len -= mlen;
	97
	98	/*
	99	* add by words.
	100	*/
	101	while ((mlen -= 2) >= 0) {
	102	if ((int)w & 0x1) {
	103	/* word is not aligned */
	104	u.c[0] = (char )w;
	105	u.c[1] = ((char )w+1);
	106	sum += u.s;
	107	w++;
	108	} else
	109	sum += *w++;
	110	ADDCARRY(sum);
	111	}
	112	if (mlen == -1)
	113	/*
114	* This mbuf has odd number of bytes.
115	* There could be a word split betwen
116	* this mbuf and the next mbuf.
117	* Save the last byte (to prepend to next mbuf).
118	*/
119	u.c[0] = (u_char )w;
120	}
121	if (len)
122	printf("cksum: out of data\n");
123	if (mlen == -1) {
124	/* The last mbuf has odd # of bytes. Follow the
125	standard (the odd byte is shifted left by 8 bits) */
126	u.c[1] = 0;
127	sum += u.s;
128	ADDCARRY(sum);
129	}
130	return (~sum & 0xffff);
131	}