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1394f032 | 1 | /* |
96f1050d | 2 | * Copyright 2004-2009 Analog Devices Inc. |
1394f032 | 3 | * |
96f1050d | 4 | * Licensed under the GPL-2 or later. |
1394f032 | 5 | * |
96f1050d RG |
6 | * An implementation of the TCP/IP protocol suite for the LINUX operating |
7 | * system. INET is implemented using the BSD Socket interface as the | |
8 | * means of communication with the user level. | |
1394f032 | 9 | * |
1394f032 BW |
10 | */ |
11 | ||
fe8015ce | 12 | #include <linux/module.h> |
1394f032 BW |
13 | #include <net/checksum.h> |
14 | #include <asm/checksum.h> | |
15 | ||
16 | #ifdef CONFIG_IP_CHECKSUM_L1 | |
17 | static unsigned short do_csum(const unsigned char *buff, int len)__attribute__((l1_text)); | |
18 | #endif | |
19 | ||
20 | static unsigned short do_csum(const unsigned char *buff, int len) | |
21 | { | |
22 | register unsigned long sum = 0; | |
23 | int swappem = 0; | |
24 | ||
25 | if (1 & (unsigned long)buff) { | |
26 | sum = *buff << 8; | |
27 | buff++; | |
28 | len--; | |
29 | ++swappem; | |
30 | } | |
31 | ||
32 | while (len > 1) { | |
33 | sum += *(unsigned short *)buff; | |
34 | buff += 2; | |
35 | len -= 2; | |
36 | } | |
37 | ||
38 | if (len > 0) | |
39 | sum += *buff; | |
40 | ||
41 | /* Fold 32-bit sum to 16 bits */ | |
42 | while (sum >> 16) | |
43 | sum = (sum & 0xffff) + (sum >> 16); | |
44 | ||
45 | if (swappem) | |
46 | sum = ((sum & 0xff00) >> 8) + ((sum & 0x00ff) << 8); | |
47 | ||
48 | return sum; | |
49 | ||
50 | } | |
51 | ||
52 | /* | |
53 | * This is a version of ip_compute_csum() optimized for IP headers, | |
54 | * which always checksum on 4 octet boundaries. | |
55 | */ | |
45b3947c | 56 | __sum16 ip_fast_csum(unsigned char *iph, unsigned int ihl) |
1394f032 | 57 | { |
45b3947c | 58 | return (__force __sum16)~do_csum(iph, ihl * 4); |
1394f032 | 59 | } |
fe8015ce | 60 | EXPORT_SYMBOL(ip_fast_csum); |
1394f032 BW |
61 | |
62 | /* | |
63 | * computes the checksum of a memory block at buff, length len, | |
64 | * and adds in "sum" (32-bit) | |
65 | * | |
66 | * returns a 32-bit number suitable for feeding into itself | |
67 | * or csum_tcpudp_magic | |
68 | * | |
69 | * this function must be called with even lengths, except | |
70 | * for the last fragment, which may be odd | |
71 | * | |
72 | * it's best to have buff aligned on a 32-bit boundary | |
73 | */ | |
45b3947c | 74 | __wsum csum_partial(const void *buff, int len, __wsum sum) |
1394f032 BW |
75 | { |
76 | /* | |
77 | * Just in case we get nasty checksum data... | |
78 | * Like 0xffff6ec3 in the case of our IPv6 multicast header. | |
79 | * We fold to begin with, as well as at the end. | |
80 | */ | |
81 | sum = (sum & 0xffff) + (sum >> 16); | |
82 | ||
83 | sum += do_csum(buff, len); | |
84 | ||
85 | sum = (sum & 0xffff) + (sum >> 16); | |
86 | ||
87 | return sum; | |
88 | } | |
fe8015ce | 89 | EXPORT_SYMBOL(csum_partial); |
1394f032 BW |
90 | |
91 | /* | |
92 | * this routine is used for miscellaneous IP-like checksums, mainly | |
93 | * in icmp.c | |
94 | */ | |
45b3947c | 95 | __sum16 ip_compute_csum(const void *buff, int len) |
1394f032 | 96 | { |
45b3947c | 97 | return (__force __sum16)~do_csum(buff, len); |
1394f032 | 98 | } |
aa286ba3 | 99 | EXPORT_SYMBOL(ip_compute_csum); |
1394f032 BW |
100 | |
101 | /* | |
102 | * copy from fs while checksumming, otherwise like csum_partial | |
103 | */ | |
104 | ||
45b3947c AV |
105 | __wsum |
106 | csum_partial_copy_from_user(const void __user *src, void *dst, | |
107 | int len, __wsum sum, int *csum_err) | |
1394f032 BW |
108 | { |
109 | if (csum_err) | |
110 | *csum_err = 0; | |
45b3947c | 111 | memcpy(dst, (__force void *)src, len); |
1394f032 BW |
112 | return csum_partial(dst, len, sum); |
113 | } | |
aa286ba3 | 114 | EXPORT_SYMBOL(csum_partial_copy_from_user); |
1394f032 BW |
115 | |
116 | /* | |
117 | * copy from ds while checksumming, otherwise like csum_partial | |
118 | */ | |
119 | ||
45b3947c | 120 | __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum) |
1394f032 BW |
121 | { |
122 | memcpy(dst, src, len); | |
123 | return csum_partial(dst, len, sum); | |
124 | } | |
fe8015ce | 125 | EXPORT_SYMBOL(csum_partial_copy); |