in_cksum.h revision 126891 
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 126891 2004-03-12 21:45:33Z trhodes $
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#if defined(__GNUC__) && !defined(__INTEL_COMPILER)
57static __inline u_int
58in_cksum_hdr(const struct ip *ip)
59{
60	register u_int sum = 0;
61
62/* __volatile is necessary here because the condition codes are used. */
63#define ADD(n)	__asm __volatile ("addl %1, %0" : "+r" (sum) : \
64    "g" (((const u_int32_t *)ip)[n / 4]))
65#define ADDC(n)	__asm __volatile ("adcl %1, %0" : "+r" (sum) : \
66    "g" (((const u_int32_t *)ip)[n / 4]))
67#define MOP	__asm __volatile ("adcl $0, %0" : "+r" (sum))
68
69	ADD(0);
70	ADDC(4);
71	ADDC(8);
72	ADDC(12);
73	ADDC(16);
74	MOP;
75#undef ADD
76#undef ADDC
77#undef MOP
78	sum = (sum & 0xffff) + (sum >> 16);
79	if (sum > 0xffff)
80		sum -= 0xffff;
81
82	return ~sum & 0xffff;
83}
84
85static __inline void
86in_cksum_update(struct ip *ip)
87{
88	int __tmpsum;
89	__tmpsum = (int)ntohs(ip->ip_sum) + 256;
90	ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16));
91}
92
93static __inline u_short
94in_addword(u_short sum, u_short b)
95{
96	/* __volatile is necessary because the condition codes are used. */
97	__asm __volatile ("addw %1, %0" : "+r" (sum) : "r" (b));
98	__asm __volatile ("adcw $0, %0" : "+r" (sum));
99
100	return (sum);
101}
102
103static __inline u_short
104in_pseudo(u_int sum, u_int b, u_int c)
105{
106	/* __volatile is necessary because the condition codes are used. */
107	__asm __volatile ("addl %1, %0" : "+r" (sum) : "g" (b));
108	__asm __volatile ("adcl %1, %0" : "+r" (sum) : "g" (c));
109	__asm __volatile ("adcl $0, %0" : "+r" (sum));
110
111	sum = (sum & 0xffff) + (sum >> 16);
112	if (sum > 0xffff)
113		sum -= 0xffff;
114	return (sum);
115}
116
117#else
118#define	in_cksum_update(ip) \
119	do { \
120		int __tmpsum; \
121		__tmpsum = (int)ntohs(ip->ip_sum) + 256; \
122		ip->ip_sum = htons(__tmpsum + (__tmpsum >> 16)); \
123	} while(0)
124
125#endif
126
127#ifdef _KERNEL
128#if !defined(__GNUC__) || defined(__INTEL_COMPILER)
129u_int in_cksum_hdr(const struct ip *ip);
130u_short in_addword(u_short sum, u_short b);
131u_short in_pseudo(u_int sum, u_int b, u_int c);
132#endif
133u_short in_cksum_skip(struct mbuf *m, int len, int skip);
134#endif /* _KERNEL */
135
136#endif /* _MACHINE_IN_CKSUM_H_ */
137