1 /*
2 * Network checksum routines
3 *
4 * Copyright (C) 1999, 2003 Hewlett-Packard Co
5 * Stephane Eranian <eranian@hpl.hp.com>
6 *
7 * Most of the code coming from arch/alpha/lib/checksum.c
8 *
9 * This file contains network checksum routines that are better done
10 * in an architecture-specific manner due to speed..
11 */
12
13 #include <linux/module.h>
14 #include <linux/string.h>
15
16 #include <asm/byteorder.h>
17
18 static inline unsigned short
from64to16(unsigned long x)19 from64to16 (unsigned long x)
20 {
21 /* add up 32-bit words for 33 bits */
22 x = (x & 0xffffffff) + (x >> 32);
23 /* add up 16-bit and 17-bit words for 17+c bits */
24 x = (x & 0xffff) + (x >> 16);
25 /* add up 16-bit and 2-bit for 16+c bit */
26 x = (x & 0xffff) + (x >> 16);
27 /* add up carry.. */
28 x = (x & 0xffff) + (x >> 16);
29 return x;
30 }
31
32 /*
33 * computes the checksum of the TCP/UDP pseudo-header
34 * returns a 16-bit checksum, already complemented.
35 */
36 __sum16
csum_tcpudp_magic(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)37 csum_tcpudp_magic (__be32 saddr, __be32 daddr, unsigned short len,
38 unsigned short proto, __wsum sum)
39 {
40 return (__force __sum16)~from64to16(
41 (__force u64)saddr + (__force u64)daddr +
42 (__force u64)sum + ((len + proto) << 8));
43 }
44
45 EXPORT_SYMBOL(csum_tcpudp_magic);
46
47 __wsum
csum_tcpudp_nofold(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)48 csum_tcpudp_nofold (__be32 saddr, __be32 daddr, unsigned short len,
49 unsigned short proto, __wsum sum)
50 {
51 unsigned long result;
52
53 result = (__force u64)saddr + (__force u64)daddr +
54 (__force u64)sum + ((len + proto) << 8);
55
56 /* Fold down to 32-bits so we don't lose in the typedef-less network stack. */
57 /* 64 to 33 */
58 result = (result & 0xffffffff) + (result >> 32);
59 /* 33 to 32 */
60 result = (result & 0xffffffff) + (result >> 32);
61 return (__force __wsum)result;
62 }
63 EXPORT_SYMBOL(csum_tcpudp_nofold);
64
65 extern unsigned long do_csum (const unsigned char *, long);
66
67 /*
68 * computes the checksum of a memory block at buff, length len,
69 * and adds in "sum" (32-bit)
70 *
71 * returns a 32-bit number suitable for feeding into itself
72 * or csum_tcpudp_magic
73 *
74 * this function must be called with even lengths, except
75 * for the last fragment, which may be odd
76 *
77 * it's best to have buff aligned on a 32-bit boundary
78 */
csum_partial(const void * buff,int len,__wsum sum)79 __wsum csum_partial(const void *buff, int len, __wsum sum)
80 {
81 u64 result = do_csum(buff, len);
82
83 /* add in old sum, and carry.. */
84 result += (__force u32)sum;
85 /* 32+c bits -> 32 bits */
86 result = (result & 0xffffffff) + (result >> 32);
87 return (__force __wsum)result;
88 }
89
90 EXPORT_SYMBOL(csum_partial);
91
92 /*
93 * this routine is used for miscellaneous IP-like checksums, mainly
94 * in icmp.c
95 */
ip_compute_csum(const void * buff,int len)96 __sum16 ip_compute_csum (const void *buff, int len)
97 {
98 return (__force __sum16)~do_csum(buff,len);
99 }
100
101 EXPORT_SYMBOL(ip_compute_csum);
102