[apple/xnu.git] / bsd / netinet / in_cksum.c

/*
 * Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1988, 1992, 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.
 *
 *	@(#)in_cksum.c	8.1 (Berkeley) 6/10/93
 */

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/kdebug.h>
#include <kern/debug.h>
#include <netinet/in.h>
#include <netinet/ip.h>

#define DBG_FNC_IN_CKSUM	NETDBG_CODE(DBG_NETIP, (3 << 8))

/*
 * 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.
 */

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

union l_util {
        u_int16_t s[2];
        u_int32_t l;
};

union q_util {
        u_int16_t s[4];
        u_int32_t l[2];
        u_int64_t q;
};

#define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)

#define REDUCE32                                                          \
    {                                                                     \
        q_util.q = sum;                                                   \
        sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3];      \
    }
#define REDUCE16                                                          \
    {                                                                     \
        q_util.q = sum;                                                   \
        l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
        sum = l_util.s[0] + l_util.s[1];                                  \
        ADDCARRY(sum);                                                    \
    }

#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}

u_int16_t inet_cksum_simple(struct mbuf *, int);

u_int16_t
inet_cksum_simple(struct mbuf *m, int len)
{
	return (inet_cksum(m, 0, 0, len));
}

#if defined(__ppc__)

extern u_short xsum_assym(u_short *p, int len, u_short xsum, int odd);

inline u_short
in_addword(u_short a, u_short b)
{
        union l_util l_util;
	u_int32_t sum = a + b;

	REDUCE;
	return (sum);
}

inline u_short
in_pseudo(u_int a, u_int b, u_int c)
{
        u_int64_t sum;
        union q_util q_util;
        union l_util l_util;

        sum = (u_int64_t) a + b + c;
        REDUCE16;
        return (sum);

}

u_int16_t
inet_cksum(struct mbuf *m, unsigned int nxt, unsigned int skip,
    unsigned int len)
{
	u_short *w;
	u_int32_t sum = 0;
	int mlen = 0;
	int starting_on_odd  = 0;

	KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_START, len,0,0,0,0);

	/* sanity check */
	if (m->m_pkthdr.len < skip + len) {
		panic("inet_cksum: mbuf len (%d) < off+len (%d+%d)\n",
		    m->m_pkthdr.len, skip, len);
	}

	/* include pseudo header checksum? */
	if (nxt != 0) {
		struct ip *iph;

		if (m->m_len < sizeof (struct ip))
			panic("inet_cksum: bad mbuf chain");

		iph = mtod(m, struct ip *);
		sum = in_pseudo(iph->ip_src.s_addr, iph->ip_dst.s_addr,
		    htonl(len + nxt));
	}

	if (skip != 0) {
		for (; skip && m; m = m->m_next) {
			if (m->m_len > skip) {
				mlen = m->m_len - skip;
				w = (u_short *)(m->m_data+skip);
				goto skip_start;
			} else {
				skip -= m->m_len;
			}
		}
	}

	for (;m && len; m = m->m_next) {
		if (m->m_len == 0)
			continue;
		mlen = m->m_len;
		w = mtod(m, u_short *);

skip_start:
		if (len < mlen)
			mlen = len;
		sum = xsum_assym(w, mlen, sum, starting_on_odd);
		len -= mlen;
		if (mlen & 0x1)
		{
		    if (starting_on_odd)
			starting_on_odd = 0;
		    else
			starting_on_odd = 1;
		}
	}

	KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_END, 0,0,0,0,0);

	return (~sum & 0xffff);
}

#else

inline u_short
in_addword(u_short a, u_short b)
{
        union l_util l_util;
        u_int32_t sum = a + b;

        REDUCE(sum);
        return (sum);
}

inline u_short
in_pseudo(u_int a, u_int b, u_int c)
{
        u_int64_t sum;
        union q_util q_util;
        union l_util l_util;

        sum = (u_int64_t) a + b + c;
        REDUCE16;
        return (sum);
}

u_int16_t
inet_cksum(struct mbuf *m, unsigned int nxt, unsigned int skip,
    unsigned int len)
{
	u_short *w;
	u_int32_t sum = 0;
	int mlen = 0;
	int byte_swapped = 0;
	union s_util s_util;
	union l_util l_util;

	KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_START, len,0,0,0,0);

	/* sanity check */
	if (m->m_pkthdr.len < skip + len) {
		panic("inet_cksum: mbuf len (%d) < off+len (%d+%d)\n",
		    m->m_pkthdr.len, skip, len);
	}

	/* include pseudo header checksum? */
	if (nxt != 0) {
		struct ip *iph;

		if (m->m_len < sizeof (struct ip))
			panic("inet_cksum: bad mbuf chain");

		iph = mtod(m, struct ip *);
		sum = in_pseudo(iph->ip_src.s_addr, iph->ip_dst.s_addr,
		    htonl(len + nxt));
	}

	if (skip != 0) {
		for (; skip && m; m = m->m_next) {
			if (m->m_len > skip) {
				mlen = m->m_len - skip;
				w = (u_short *)(m->m_data+skip);
				goto skip_start;
			} else {
				skip -= m->m_len;
			}
		}
	}
	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;
		}
skip_start:
		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 by %d\n", len);
	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;
	KERNEL_DEBUG(DBG_FNC_IN_CKSUM | DBG_FUNC_END, 0,0,0,0,0);
	return (~sum & 0xffff);
}

#endif
Commit	Line	Data
1c79356b	1	/*
2d21ac55	2	* Copyright (c) 2000-2006 Apple Computer, Inc. All rights reserved.
5d5c5d0d	3	*
2d21ac55	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
1c79356b	5	*
2d21ac55 A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
8f6c56a5	14	*
2d21ac55 A	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
8f6c56a5 A	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
8f6c56a5 A	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
2d21ac55 A	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
8f6c56a5	25	*
2d21ac55	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
1c79356b A	27	*/
	28	/*
	29	* Copyright (c) 1988, 1992, 1993
	30	* The Regents of the University of California. All rights reserved.
	31	*
	32	* Redistribution and use in source and binary forms, with or without
	33	* modification, are permitted provided that the following conditions
	34	* are met:
	35	* 1. Redistributions of source code must retain the above copyright
	36	* notice, this list of conditions and the following disclaimer.
	37	* 2. Redistributions in binary form must reproduce the above copyright
	38	* notice, this list of conditions and the following disclaimer in the
	39	* documentation and/or other materials provided with the distribution.
	40	* 3. All advertising materials mentioning features or use of this software
	41	* must display the following acknowledgement:
	42	* This product includes software developed by the University of
	43	* California, Berkeley and its contributors.
	44	* 4. Neither the name of the University nor the names of its contributors
	45	* may be used to endorse or promote products derived from this software
	46	* without specific prior written permission.
	47	*
	48	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	49	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	50	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	51	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	52	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	53	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	54	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	55	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	56	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	57	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	58	* SUCH DAMAGE.
	59	*
	60	* @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
	61	*/
	62
	63	#include <sys/param.h>
	64	#include <sys/mbuf.h>
	65	#include <sys/kdebug.h>
2d21ac55 A	66	#include <kern/debug.h>
	67	#include <netinet/in.h>
	68	#include <netinet/ip.h>
1c79356b A	69
	70	#define DBG_FNC_IN_CKSUM NETDBG_CODE(DBG_NETIP, (3 << 8))
	71
	72	/*
	73	* Checksum routine for Internet Protocol family headers (Portable Version).
	74	*
	75	* This routine is very heavily used in the network
	76	* code and should be modified for each CPU to be as fast as possible.
	77	*/
	78
0b4e3aa0 A	79	union s_util {
	80	char c[2];
	81	u_short s;
	82	};
1c79356b	83
0b4e3aa0 A	84	union l_util {
0b4e3aa0 A	85	u_int16_t s[2];
2d21ac55	86	u_int32_t l;
0b4e3aa0	87	};
1c79356b	88
0b4e3aa0 A	89	union q_util {
	90	u_int16_t s[4];
	91	u_int32_t l[2];
	92	u_int64_t q;
2d21ac55	93	};
0b4e3aa0 A	94
	95	#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
	96
	97	#define REDUCE32 \
	98	{ \
	99	q_util.q = sum; \
	100	sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
	101	}
	102	#define REDUCE16 \
	103	{ \
	104	q_util.q = sum; \
	105	l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \
	106	sum = l_util.s[0] + l_util.s[1]; \
	107	ADDCARRY(sum); \
	108	}
	109
	110	#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
	111
2d21ac55 A	112	u_int16_t inet_cksum_simple(struct mbuf *, int);
	113
	114	u_int16_t
	115	inet_cksum_simple(struct mbuf *m, int len)
	116	{
	117	return (inet_cksum(m, 0, 0, len));
	118	}
1c79356b	119
2d21ac55 A	120	#if defined(__ppc__)
	121
	122	extern u_short xsum_assym(u_short *p, int len, u_short xsum, int odd);
	123
	124	inline u_short
0b4e3aa0 A	125	in_addword(u_short a, u_short b)
0b4e3aa0 A	126	{
2d21ac55	127	union l_util l_util;
0b4e3aa0	128	u_int32_t sum = a + b;
2d21ac55	129
0b4e3aa0 A	130	REDUCE;
	131	return (sum);
	132	}
	133
2d21ac55	134	inline u_short
0b4e3aa0 A	135	in_pseudo(u_int a, u_int b, u_int c)
	136	{
	137	u_int64_t sum;
	138	union q_util q_util;
2d21ac55	139	union l_util l_util;
0b4e3aa0 A	140
	141	sum = (u_int64_t) a + b + c;
	142	REDUCE16;
	143	return (sum);
	144
	145	}
	146
2d21ac55 A	147	u_int16_t
	148	inet_cksum(struct mbuf *m, unsigned int nxt, unsigned int skip,
	149	unsigned int len)
1c79356b	150	{
2d21ac55 A	151	u_short *w;
	152	u_int32_t sum = 0;
	153	int mlen = 0;
1c79356b A	154	int starting_on_odd = 0;
1c79356b A	155
1c79356b A	156	KERNEL_DEBUG(DBG_FNC_IN_CKSUM \| DBG_FUNC_START, len,0,0,0,0);
1c79356b A	157
2d21ac55 A	158	/* sanity check */
	159	if (m->m_pkthdr.len < skip + len) {
	160	panic("inet_cksum: mbuf len (%d) < off+len (%d+%d)\n",
	161	m->m_pkthdr.len, skip, len);
	162	}
1c79356b	163
2d21ac55 A	164	/* include pseudo header checksum? */
	165	if (nxt != 0) {
	166	struct ip *iph;
1c79356b	167
2d21ac55 A	168	if (m->m_len < sizeof (struct ip))
2d21ac55 A	169	panic("inet_cksum: bad mbuf chain");
1c79356b	170
2d21ac55 A	171	iph = mtod(m, struct ip *);
	172	sum = in_pseudo(iph->ip_src.s_addr, iph->ip_dst.s_addr,
	173	htonl(len + nxt));
	174	}
1c79356b	175
2d21ac55 A	176	if (skip != 0) {
	177	for (; skip && m; m = m->m_next) {
	178	if (m->m_len > skip) {
	179	mlen = m->m_len - skip;
	180	w = (u_short *)(m->m_data+skip);
	181	goto skip_start;
	182	} else {
	183	skip -= m->m_len;
	184	}
	185	}
	186	}
0b4e3aa0	187
0b4e3aa0 A	188	for (;m && len; m = m->m_next) {
	189	if (m->m_len == 0)
	190	continue;
	191	mlen = m->m_len;
	192	w = mtod(m, u_short *);
	193
765c9de3	194	skip_start:
0b4e3aa0 A	195	if (len < mlen)
0b4e3aa0 A	196	mlen = len;
0b4e3aa0 A	197	sum = xsum_assym(w, mlen, sum, starting_on_odd);
	198	len -= mlen;
	199	if (mlen & 0x1)
	200	{
	201	if (starting_on_odd)
	202	starting_on_odd = 0;
	203	else
	204	starting_on_odd = 1;
	205	}
	206	}
	207
2d21ac55 A	208	KERNEL_DEBUG(DBG_FNC_IN_CKSUM \| DBG_FUNC_END, 0,0,0,0,0);
2d21ac55 A	209
0b4e3aa0 A	210	return (~sum & 0xffff);
0b4e3aa0 A	211	}
2d21ac55	212
1c79356b A	213	#else
1c79356b A	214
2d21ac55	215	inline u_short
0b4e3aa0	216	in_addword(u_short a, u_short b)
2d21ac55 A	217	{
2d21ac55 A	218	union l_util l_util;
0b4e3aa0	219	u_int32_t sum = a + b;
2d21ac55	220
0b4e3aa0 A	221	REDUCE(sum);
0b4e3aa0 A	222	return (sum);
2d21ac55	223	}
1c79356b	224
2d21ac55	225	inline u_short
0b4e3aa0 A	226	in_pseudo(u_int a, u_int b, u_int c)
0b4e3aa0 A	227	{
2d21ac55	228	u_int64_t sum;
0b4e3aa0	229	union q_util q_util;
2d21ac55	230	union l_util l_util;
1c79356b	231
0b4e3aa0 A	232	sum = (u_int64_t) a + b + c;
	233	REDUCE16;
	234	return (sum);
	235	}
1c79356b	236
2d21ac55 A	237	u_int16_t
	238	inet_cksum(struct mbuf *m, unsigned int nxt, unsigned int skip,
	239	unsigned int len)
1c79356b	240	{
2d21ac55 A	241	u_short *w;
	242	u_int32_t sum = 0;
	243	int mlen = 0;
1c79356b	244	int byte_swapped = 0;
0b4e3aa0	245	union s_util s_util;
2d21ac55	246	union l_util l_util;
1c79356b A	247
	248	KERNEL_DEBUG(DBG_FNC_IN_CKSUM \| DBG_FUNC_START, len,0,0,0,0);
	249
2d21ac55 A	250	/* sanity check */
	251	if (m->m_pkthdr.len < skip + len) {
	252	panic("inet_cksum: mbuf len (%d) < off+len (%d+%d)\n",
	253	m->m_pkthdr.len, skip, len);
0b4e3aa0	254	}
0b4e3aa0	255
2d21ac55 A	256	/* include pseudo header checksum? */
	257	if (nxt != 0) {
	258	struct ip *iph;
0b4e3aa0	259
2d21ac55 A	260	if (m->m_len < sizeof (struct ip))
	261	panic("inet_cksum: bad mbuf chain");
	262
	263	iph = mtod(m, struct ip *);
	264	sum = in_pseudo(iph->ip_src.s_addr, iph->ip_dst.s_addr,
	265	htonl(len + nxt));
	266	}
0b4e3aa0	267
2d21ac55 A	268	if (skip != 0) {
	269	for (; skip && m; m = m->m_next) {
	270	if (m->m_len > skip) {
	271	mlen = m->m_len - skip;
	272	w = (u_short *)(m->m_data+skip);
	273	goto skip_start;
	274	} else {
	275	skip -= m->m_len;
	276	}
	277	}
	278	}
0b4e3aa0 A	279	for (;m && len; m = m->m_next) {
	280	if (m->m_len == 0)
	281	continue;
	282	w = mtod(m, u_short *);
	283
	284	if (mlen == -1) {
	285	/*
	286	* The first byte of this mbuf is the continuation
	287	* of a word spanning between this mbuf and the
	288	* last mbuf.
	289	*
	290	* s_util.c[0] is already saved when scanning previous
	291	* mbuf.
	292	*/
	293	s_util.c[1] = (char )w;
	294	sum += s_util.s;
	295	w = (u_short )((char )w + 1);
	296	mlen = m->m_len - 1;
	297	len--;
	298	} else {
2d21ac55	299	mlen = m->m_len;
0b4e3aa0	300	}
0b4e3aa0	301	skip_start:
765c9de3	302	if (len < mlen)
2d21ac55	303	mlen = len;
0b4e3aa0 A	304
	305	len -= mlen;
	306	/*
	307	* Force to even boundary.
	308	*/
	309	if ((1 & (int) w) && (mlen > 0)) {
	310	REDUCE;
	311	sum <<= 8;
	312	s_util.c[0] = (u_char )w;
	313	w = (u_short )((char )w + 1);
	314	mlen--;
	315	byte_swapped = 1;
	316	}
	317	/*
	318	* Unroll the loop to make overhead from
	319	* branches &c small.
	320	*/
	321	while ((mlen -= 32) >= 0) {
	322	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	323	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
1c79356b A	324	sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
	325	sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
	326	w += 16;
	327	}
	328	mlen += 32;
	329	while ((mlen -= 8) >= 0) {
	330	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	331	w += 4;
	332	}
	333	mlen += 8;
	334	if (mlen == 0 && byte_swapped == 0)
	335	continue;
	336	REDUCE;
	337	while ((mlen -= 2) >= 0) {
	338	sum += *w++;
	339	}
	340	if (byte_swapped) {
	341	REDUCE;
	342	sum <<= 8;
	343	byte_swapped = 0;
	344	if (mlen == -1) {
	345	s_util.c[1] = (char )w;
	346	sum += s_util.s;
	347	mlen = 0;
	348	} else
	349	mlen = -1;
	350	} else if (mlen == -1)
	351	s_util.c[0] = (char )w;
	352	}
	353	if (len)
2d21ac55	354	printf("cksum: out of data by %d\n", len);
1c79356b A	355	if (mlen == -1) {
	356	/* The last mbuf has odd # of bytes. Follow the
	357	standard (the odd byte may be shifted left by 8 bits
	358	or not as determined by endian-ness of the machine) */
	359	s_util.c[1] = 0;
	360	sum += s_util.s;
	361	}
	362	REDUCE;
	363	KERNEL_DEBUG(DBG_FNC_IN_CKSUM \| DBG_FUNC_END, 0,0,0,0,0);
	364	return (~sum & 0xffff);
	365	}
	366
	367	#endif