[unix-history] / usr / src / 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 are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *	@(#)in_cksum.c	7.2 (Berkeley) %G%
 */

#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
7c060394 MK	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 are permitted
616d42db KB	6	* provided that the above copyright notice and this paragraph are
	7	* duplicated in all such forms and that any documentation,
	8	* advertising materials, and other materials related to such
	9	* distribution and use acknowledge that the software was developed
	10	* by the University of California, Berkeley. The name of the
	11	* University may not be used to endorse or promote products derived
	12	* from this software without specific prior written permission.
	13	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
	15	* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
7c060394	16	*
616d42db	17	* @(#)in_cksum.c 7.2 (Berkeley) %G%
7c060394 MK	18	*/
	19
	20	#include "../h/types.h"
	21	#include "../h/mbuf.h"
	22
	23	/*
	24	* Checksum routine for Internet Protocol family headers (Portable Version).
	25	*
	26	* This routine is very heavily used in the network
	27	* code and should be modified for each CPU to be as fast as possible.
	28	*/
	29
	30	#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
	31	#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
	32
	33	in_cksum_c(m, len)
	34	register struct mbuf *m;
	35	register int len;
	36	{
	37	register u_short *w;
	38	register int sum = 0;
	39	register int mlen = 0;
	40	int byte_swapped = 0;
	41
	42	union {
	43	char c[2];
	44	u_short s;
	45	} s_util;
	46	union {
	47	u_short s[2];
	48	long l;
	49	} l_util;
	50
	51	for (;m && len; m = m->m_next) {
	52	if (m->m_len == 0)
	53	continue;
	54	w = mtod(m, u_short *);
	55	if (mlen == -1) {
	56	/*
	57	* The first byte of this mbuf is the continuation
	58	* of a word spanning between this mbuf and the
	59	* last mbuf.
	60	*
	61	* s_util.c[0] is already saved when scanning previous
	62	* mbuf.
	63	*/
	64	s_util.c[1] = (char )w;
	65	sum += s_util.s;
	66	w = (u_short )((char )w + 1);
	67	mlen = m->m_len - 1;
	68	len--;
	69	} else
	70	mlen = m->m_len;
	71	if (len < mlen)
	72	mlen = len;
	73	len -= mlen;
	74	/*
	75	* Force to even boundary.
	76	*/
	77	if ((1 & (int) w) && (mlen > 0)) {
	78	REDUCE;
	79	sum <<= 8;
	80	s_util.c[0] = (u_char )w;
	81	w = (u_short )((char )w + 1);
82	mlen--;
83	byte_swapped = 1;
84	}
85	/*
86	* Unroll the loop to make overhead from
87	* branches &c small.
88	*/
89	while ((mlen -= 32) >= 0) {
90	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
91	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
92	sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
93	sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
94	w += 16;
95	}
96	mlen += 32;
97	while ((mlen -= 8) >= 0) {
98	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
99	w += 4;
100	}
101	mlen += 8;
102	if (mlen == 0 && byte_swapped == 0)
103	continue;
104	REDUCE;
105	while ((mlen -= 2) >= 0) {
106	sum += *w++;
107	}
108	if (byte_swapped) {
109	REDUCE;
110	sum <<= 8;
111	byte_swapped = 0;
112	if (mlen == -1) {
113	s_util.c[1] = (char )w;
114	sum += s_util.s;
115	mlen = 0;
116	} else
117	mlen = -1;
118	} else if (mlen == -1)
119	s_util.c[0] = (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 may be shifted left by 8 bits
126	or not as determined by endian-ness of the machine) */
127	s_util.c[1] = 0;
128	sum += s_util.s;
129	}
130	REDUCE;
131	return (~sum & 0xffff);
132	}