[unix-history] / sys / netinet / in_cksum.c

/*
 * Copyright (c) 1988 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: @(#)in_cksum.c	7.3 (Berkeley) 6/28/90
 *	$Id$
 */

#include "../h/types.h"
#include "../h/mbuf.h"

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

#define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}

in_cksum_c(m, len)
	register struct mbuf *m;
	register int len;
{
	register u_short *w;
	register int sum = 0;
	register int mlen = 0;
	int byte_swapped = 0;

	union {
		char	c[2];
		u_short	s;
	} s_util;
	union {
		u_short s[2];
		long	l;
	} l_util;

	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.
			 *
			 * s_util.c[0] is already saved when scanning previous 
			 * mbuf.
			 */
			s_util.c[1] = *(char *)w;
			sum += s_util.s;
			w = (u_short *)((char *)w + 1);
			mlen = m->m_len - 1;
			len--;
		} else
			mlen = m->m_len;
		if (len < mlen)
			mlen = len;
		len -= mlen;
		/*
		 * Force to even boundary.
		 */
		if ((1 & (int) w) && (mlen > 0)) {
			REDUCE;
			sum <<= 8;
			s_util.c[0] = *(u_char *)w;
			w = (u_short *)((char *)w + 1);
			mlen--;
			byte_swapped = 1;
		}
		/*
		 * Unroll the loop to make overhead from
		 * branches &c small.
		 */
		while ((mlen -= 32) >= 0) {
			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
			sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
			sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
			sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
			w += 16;
		}
		mlen += 32;
		while ((mlen -= 8) >= 0) {
			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
			w += 4;
		}
		mlen += 8;
		if (mlen == 0 && byte_swapped == 0)
			continue;
		REDUCE;
		while ((mlen -= 2) >= 0) {
			sum += *w++;
		}
		if (byte_swapped) {
			REDUCE;
			sum <<= 8;
			byte_swapped = 0;
			if (mlen == -1) {
				s_util.c[1] = *(char *)w;
				sum += s_util.s;
				mlen = 0;
			} else
				mlen = -1;
		} else if (mlen == -1)
			s_util.c[0] = *(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 may be shifted left by 8 bits
		   or not as determined by endian-ness of the machine) */
		s_util.c[1] = 0;
		sum += s_util.s;
	}
	REDUCE;
	return (~sum & 0xffff);
}
Commit	Line	Data
15637ed4 RG	1	/*
	2	* Copyright (c) 1988 Regents of the University of California.
	3	* All rights reserved.
	4	*
	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.
	32	*
38e82238 RG	33	* from: @(#)in_cksum.c 7.3 (Berkeley) 6/28/90
38e82238 RG	34	* $Id$
15637ed4 RG	35	*/
	36
	37	#include "../h/types.h"
	38	#include "../h/mbuf.h"
	39
	40	/*
	41	* Checksum routine for Internet Protocol family headers (Portable Version).
	42	*
	43	* This routine is very heavily used in the network
	44	* code and should be modified for each CPU to be as fast as possible.
	45	*/
	46
	47	#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
	48	#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
	49
	50	in_cksum_c(m, len)
	51	register struct mbuf *m;
	52	register int len;
	53	{
	54	register u_short *w;
	55	register int sum = 0;
	56	register int mlen = 0;
	57	int byte_swapped = 0;
	58
	59	union {
	60	char c[2];
	61	u_short s;
	62	} s_util;
	63	union {
	64	u_short s[2];
	65	long l;
	66	} l_util;
	67
	68	for (;m && len; m = m->m_next) {
	69	if (m->m_len == 0)
	70	continue;
	71	w = mtod(m, u_short *);
	72	if (mlen == -1) {
	73	/*
	74	* The first byte of this mbuf is the continuation
	75	* of a word spanning between this mbuf and the
	76	* last mbuf.
	77	*
	78	* s_util.c[0] is already saved when scanning previous
	79	* mbuf.
	80	*/
	81	s_util.c[1] = (char )w;
	82	sum += s_util.s;
	83	w = (u_short )((char )w + 1);
	84	mlen = m->m_len - 1;
	85	len--;
	86	} else
	87	mlen = m->m_len;
	88	if (len < mlen)
	89	mlen = len;
	90	len -= mlen;
	91	/*
	92	* Force to even boundary.
	93	*/
	94	if ((1 & (int) w) && (mlen > 0)) {
	95	REDUCE;
	96	sum <<= 8;
	97	s_util.c[0] = (u_char )w;
	98	w = (u_short )((char )w + 1);
99	mlen--;
100	byte_swapped = 1;
101	}
102	/*
103	* Unroll the loop to make overhead from
104	* branches &c small.
105	*/
106	while ((mlen -= 32) >= 0) {
107	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
108	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
109	sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
110	sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
111	w += 16;
112	}
113	mlen += 32;
114	while ((mlen -= 8) >= 0) {
115	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
116	w += 4;
117	}
118	mlen += 8;
119	if (mlen == 0 && byte_swapped == 0)
120	continue;
121	REDUCE;
122	while ((mlen -= 2) >= 0) {
123	sum += *w++;
124	}
125	if (byte_swapped) {
126	REDUCE;
127	sum <<= 8;
128	byte_swapped = 0;
129	if (mlen == -1) {
130	s_util.c[1] = (char )w;
131	sum += s_util.s;
132	mlen = 0;
133	} else
134	mlen = -1;
135	} else if (mlen == -1)
136	s_util.c[0] = (char )w;
137	}
138	if (len)
139	printf("cksum: out of data\n");
140	if (mlen == -1) {
141	/* The last mbuf has odd # of bytes. Follow the
142	standard (the odd byte may be shifted left by 8 bits
143	or not as determined by endian-ness of the machine) */
144	s_util.c[1] = 0;
145	sum += s_util.s;
146	}
147	REDUCE;
148	return (~sum & 0xffff);
149	}