[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. 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.
2f5f8996	13	* 3. Neither the name of the University nor the names of its contributors
f0cbd3ec FB	14	* may be used to endorse or promote products derived from this software
	15	* without specific prior written permission.
	16	*
	17	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	18	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	19	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	20	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	21	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	22	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	23	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	24	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	25	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	26	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	27	* SUCH DAMAGE.
	28	*
	29	* @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
	30	* in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
	31	*/
	32
	33	#include <slirp.h>
	34
	35	/*
	36	* Checksum routine for Internet Protocol family headers (Portable Version).
	37	*
	38	* This routine is very heavily used in the network
	39	* code and should be modified for each CPU to be as fast as possible.
5fafdf24	40	*
f0cbd3ec FB	41	* XXX Since we will never span more than 1 mbuf, we can optimise this
	42	*/
	43
	44	#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
	45	#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
	46
	47	int cksum(struct mbuf *m, int len)
	48	{
	49	register u_int16_t *w;
	50	register int sum = 0;
	51	register int mlen = 0;
	52	int byte_swapped = 0;
	53
	54	union {
	55	u_int8_t c[2];
	56	u_int16_t s;
	57	} s_util;
	58	union {
	59	u_int16_t s[2];
	60	u_int32_t l;
	61	} l_util;
5fafdf24	62
f0cbd3ec FB	63	if (m->m_len == 0)
	64	goto cont;
	65	w = mtod(m, u_int16_t *);
5fafdf24	66
f0cbd3ec	67	mlen = m->m_len;
5fafdf24	68
f0cbd3ec FB	69	if (len < mlen)
	70	mlen = len;
	71	len -= mlen;
	72	/*
	73	* Force to even boundary.
	74	*/
	75	if ((1 & (long) w) && (mlen > 0)) {
	76	REDUCE;
	77	sum <<= 8;
	78	s_util.c[0] = (u_int8_t )w;
	79	w = (u_int16_t )((int8_t )w + 1);
	80	mlen--;
	81	byte_swapped = 1;
	82	}
	83	/*
	84	* Unroll the loop to make overhead from
	85	* branches &c small.
	86	*/
	87	while ((mlen -= 32) >= 0) {
	88	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	89	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
	90	sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
	91	sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
	92	w += 16;
	93	}
	94	mlen += 32;
	95	while ((mlen -= 8) >= 0) {
	96	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	97	w += 4;
	98	}
	99	mlen += 8;
	100	if (mlen == 0 && byte_swapped == 0)
	101	goto cont;
	102	REDUCE;
	103	while ((mlen -= 2) >= 0) {
	104	sum += *w++;
	105	}
5fafdf24	106
f0cbd3ec FB	107	if (byte_swapped) {
	108	REDUCE;
	109	sum <<= 8;
	110	byte_swapped = 0;
	111	if (mlen == -1) {
	112	s_util.c[1] = (u_int8_t )w;
	113	sum += s_util.s;
	114	mlen = 0;
	115	} else
3b46e624	116
f0cbd3ec FB	117	mlen = -1;
	118	} else if (mlen == -1)
	119	s_util.c[0] = (u_int8_t )w;
5fafdf24	120
f0cbd3ec FB	121	cont:
	122	#ifdef DEBUG
	123	if (len) {
	124	DEBUG_ERROR((dfd, "cksum: out of data\n"));
	125	DEBUG_ERROR((dfd, " len = %d\n", len));
	126	}
	127	#endif
	128	if (mlen == -1) {
	129	/* The last mbuf has odd # of bytes. Follow the
	130	standard (the odd byte may be shifted left by 8 bits
	131	or not as determined by endian-ness of the machine) */
	132	s_util.c[1] = 0;
	133	sum += s_util.s;
	134	}
	135	REDUCE;
	136	return (~sum & 0xffff);
	137	}