[qemu.git] / slirp / cksum.c

/*
 * 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
 * in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
 */

#include <slirp.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.
 * 
 * XXX Since we will never span more than 1 mbuf, we can optimise this
 */

#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);}

int cksum(struct mbuf *m, int len)
{
	register u_int16_t *w;
	register int sum = 0;
	register int mlen = 0;
	int byte_swapped = 0;

	union {
		u_int8_t	c[2];
		u_int16_t	s;
	} s_util;
	union {
		u_int16_t s[2];
		u_int32_t l;
	} l_util;
	
	if (m->m_len == 0)
	   goto cont;
	w = mtod(m, u_int16_t *);
	
	mlen = m->m_len;
	
	if (len < mlen)
	   mlen = len;
	len -= mlen;
	/*
	 * Force to even boundary.
	 */
	if ((1 & (long) w) && (mlen > 0)) {
		REDUCE;
		sum <<= 8;
		s_util.c[0] = *(u_int8_t *)w;
		w = (u_int16_t *)((int8_t *)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)
	   goto cont;
	REDUCE;
	while ((mlen -= 2) >= 0) {
		sum += *w++;
	}
	
	if (byte_swapped) {
		REDUCE;
		sum <<= 8;
		byte_swapped = 0;
		if (mlen == -1) {
			s_util.c[1] = *(u_int8_t *)w;
			sum += s_util.s;
			mlen = 0;
		} else
		   
		   mlen = -1;
	} else if (mlen == -1)
	   s_util.c[0] = *(u_int8_t *)w;
	
cont:
#ifdef DEBUG
	if (len) {
		DEBUG_ERROR((dfd, "cksum: out of data\n"));
		DEBUG_ERROR((dfd, " len = %d\n", len));
	}
#endif
	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
f0cbd3ec FB	1	/*
	2	* Copyright (c) 1988, 1992, 1993
	3	* The Regents of the University of California. 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	*
	33	* @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
	34	* in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
	35	*/
	36
	37	#include <slirp.h>
	38
	39	/*
	40	* Checksum routine for Internet Protocol family headers (Portable Version).
	41	*
	42	* This routine is very heavily used in the network
	43	* code and should be modified for each CPU to be as fast as possible.
	44	*
	45	* XXX Since we will never span more than 1 mbuf, we can optimise this
	46	*/
	47
	48	#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
	49	#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
	50
	51	int cksum(struct mbuf *m, int len)
	52	{
	53	register u_int16_t *w;
	54	register int sum = 0;
	55	register int mlen = 0;
	56	int byte_swapped = 0;
	57
	58	union {
	59	u_int8_t c[2];
	60	u_int16_t s;
	61	} s_util;
	62	union {
	63	u_int16_t s[2];
	64	u_int32_t l;
65	} l_util;
66
67	if (m->m_len == 0)
68	goto cont;
69	w = mtod(m, u_int16_t *);
70
71	mlen = m->m_len;
72
73	if (len < mlen)
74	mlen = len;
75	len -= mlen;
76	/*
77	* Force to even boundary.
78	*/
79	if ((1 & (long) w) && (mlen > 0)) {
80	REDUCE;
81	sum <<= 8;
82	s_util.c[0] = (u_int8_t )w;
83	w = (u_int16_t )((int8_t )w + 1);
84	mlen--;
85	byte_swapped = 1;
86	}
87	/*
88	* Unroll the loop to make overhead from
89	* branches &c small.
90	*/
91	while ((mlen -= 32) >= 0) {
92	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
93	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
94	sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
95	sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
96	w += 16;
97	}
98	mlen += 32;
99	while ((mlen -= 8) >= 0) {
100	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
101	w += 4;
102	}
103	mlen += 8;
104	if (mlen == 0 && byte_swapped == 0)
105	goto cont;
106	REDUCE;
107	while ((mlen -= 2) >= 0) {
108	sum += *w++;
109	}
110
111	if (byte_swapped) {
112	REDUCE;
113	sum <<= 8;
114	byte_swapped = 0;
115	if (mlen == -1) {
116	s_util.c[1] = (u_int8_t )w;
117	sum += s_util.s;
118	mlen = 0;
119	} else
120
121	mlen = -1;
122	} else if (mlen == -1)
123	s_util.c[0] = (u_int8_t )w;
124
125	cont:
126	#ifdef DEBUG
127	if (len) {
128	DEBUG_ERROR((dfd, "cksum: out of data\n"));
129	DEBUG_ERROR((dfd, " len = %d\n", len));
130	}
131	#endif
132	if (mlen == -1) {
133	/* The last mbuf has odd # of bytes. Follow the
134	standard (the odd byte may be shifted left by 8 bits
135	or not as determined by endian-ness of the machine) */
136	s_util.c[1] = 0;
137	sum += s_util.s;
138	}
139	REDUCE;
140	return (~sum & 0xffff);
141	}