in_cksum.h revision 92761 
1/*-
2 * Copyright (c) 1990 The 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 *
33 *	from tahoe:	in_cksum.c	1.2	86/01/05
34 *	from:		@(#)in_cksum.c	1.3 (Berkeley) 1/19/91
35 *	from: Id: in_cksum.c,v 1.8 1995/12/03 18:35:19 bde Exp
36 * $FreeBSD: head/sys/i386/include/in_cksum.h 92761 2002-03-20 05:48:58Z alfred $
37 */
38
39#ifndef _MACHINE_IN_CKSUM_H_
40#define	_MACHINE_IN_CKSUM_H_	1
41
42/*
43 * MP safe (alfred)
44 */
45
46#include <sys/cdefs.h>
47
48#define in_cksum(m, len)	in_cksum_skip(m, len, 0)
49
50/*
51 * It it useful to have an Internet checksum routine which is inlineable
52 * and optimized specifically for the task of computing IP header checksums
53 * in the normal case (where there are no options and the header length is
54 * therefore always exactly five 32-bit words.
55 */
56#ifdef __GNUC__
57static __inline u_int
58in_cksum_hdr(const struct ip *ip)
59{
60	register u_int sum = 0;
61
62#define ADD(n)	__asm("addl " #n "(%1), %0" : "+r" (sum) : "r" (ip))
63#define ADDC(n)	__asm("adcl " #n "(%1), %0" : "+r" (sum) : "r" (ip))
64#define MOP	__asm("adcl         $0, %0" : "+r" (sum))
65
66	ADD(0);
67	ADDC(4);
68	ADDC(8);
69	ADDC(12);
70	ADDC(16);
71	MOP;
72#undef ADD
73#undef ADDC
74#undef MOP
75	sum = (sum & 0xffff) + (sum >> 16);
76	if (sum > 0xffff)
77		sum -= 0xffff;
78
79	return ~sum & 0xffff;
80}
81
82static __inline void
83in_cksum_update(struct ip *ip)
84{
85	int __tmpsum;
86	__tmpsum = (int)ntohs(ip->ip_sum) + 256;
87	ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16));
88}
89
90static __inline u_short
91in_addword(u_short sum, u_short b)
92{
93
94	__asm("addw %1, %0" : "+r" (sum) : "r" (b));
95	__asm("adcw $0, %0" : "+r" (sum));
96
97	return (sum);
98}
99
100static __inline u_short
101in_pseudo(u_int sum, u_int b, u_int c)
102{
103
104	__asm("addl %1, %0" : "+r" (sum) : "r" (b));
105	__asm("adcl %1, %0" : "+r" (sum) : "r" (c));
106	__asm("adcl $0, %0" : "+r" (sum));
107
108	sum = (sum & 0xffff) + (sum >> 16);
109	if (sum > 0xffff)
110		sum -= 0xffff;
111	return (sum);
112}
113
114#else
115u_int in_cksum_hdr(const struct ip *);
116#define	in_cksum_update(ip) \
117	do { \
118		int __tmpsum; \
119		__tmpsum = (int)ntohs(ip->ip_sum) + 256; \
120		ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16)); \
121	} while(0)
122
123#endif
124
125#ifdef _KERNEL
126u_short	in_cksum_skip(struct mbuf *m, int len, int skip);
127#endif /* _KERNEL */
128
129#endif /* _MACHINE_IN_CKSUM_H_ */
130