xref: /freebsd/sys/i386/include/in_cksum.h (revision edf8578117e8844e02c0121147f45e4609b30680)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1990 The Regents of the University of California.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  *	from tahoe:	in_cksum.c	1.2	86/01/05
32  *	from:		@(#)in_cksum.c	1.3 (Berkeley) 1/19/91
33  *	from: Id: in_cksum.c,v 1.8 1995/12/03 18:35:19 bde Exp
34  */
35 
36 #ifndef _MACHINE_IN_CKSUM_H_
37 #define	_MACHINE_IN_CKSUM_H_	1
38 
39 #include <sys/cdefs.h>
40 
41 #define in_cksum(m, len)	in_cksum_skip(m, len, 0)
42 
43 /*
44  * It it useful to have an Internet checksum routine which is inlineable
45  * and optimized specifically for the task of computing IP header checksums
46  * in the normal case (where there are no options and the header length is
47  * therefore always exactly five 32-bit words.
48  */
49 #if defined(IPVERSION) && (IPVERSION == 4)
50 static __inline u_int
51 in_cksum_hdr(const struct ip *ip)
52 {
53 	u_int sum = 0;
54 
55 	__asm(
56 		"addl %1, %0\n"
57 		"adcl %2, %0\n"
58 		"adcl %3, %0\n"
59 		"adcl %4, %0\n"
60 		"adcl %5, %0\n"
61 		"adcl $0, %0"
62 		: "+r" (sum)
63 		: "g" (((const u_int32_t *)ip)[0]),
64 		  "g" (((const u_int32_t *)ip)[1]),
65 		  "g" (((const u_int32_t *)ip)[2]),
66 		  "g" (((const u_int32_t *)ip)[3]),
67 		  "g" (((const u_int32_t *)ip)[4])
68 		: "cc"
69 	);
70 	sum = (sum & 0xffff) + (sum >> 16);
71 	if (sum > 0xffff)
72 		sum -= 0xffff;
73 
74 	return ~sum & 0xffff;
75 }
76 #endif
77 
78 static __inline u_short
79 in_addword(u_short sum, u_short b)
80 {
81 	__asm(
82 		"addw %1, %0\n"
83 		"adcw $0, %0"
84 		: "+r" (sum)
85 		: "g" (b)
86 		: "cc"
87 	);
88 	return (sum);
89 }
90 
91 static __inline u_short
92 in_pseudo(u_int sum, u_int b, u_int c)
93 {
94 	__asm(
95 		"addl %1, %0\n"
96 		"adcl %2, %0\n"
97 		"adcl $0, %0"
98 		: "+r" (sum)
99 		: "g" (b),
100 		  "g" (c)
101 		: "cc"
102 	);
103 	sum = (sum & 0xffff) + (sum >> 16);
104 	if (sum > 0xffff)
105 		sum -= 0xffff;
106 	return (sum);
107 }
108 
109 #ifdef _KERNEL
110 
111 #define	HAVE_MD_IN_CKSUM
112 
113 u_short in_cksum_skip(struct mbuf *m, int len, int skip);
114 #endif /* _KERNEL */
115 
116 #endif /* _MACHINE_IN_CKSUM_H_ */
117