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1 | #ifndef __ASM_GENERIC_CHECKSUM_H |
2 | #define __ASM_GENERIC_CHECKSUM_H | |
3 | ||
4 | /* | |
5 | * computes the checksum of a memory block at buff, length len, | |
6 | * and adds in "sum" (32-bit) | |
7 | * | |
8 | * returns a 32-bit number suitable for feeding into itself | |
9 | * or csum_tcpudp_magic | |
10 | * | |
11 | * this function must be called with even lengths, except | |
12 | * for the last fragment, which may be odd | |
13 | * | |
14 | * it's best to have buff aligned on a 32-bit boundary | |
15 | */ | |
16 | extern __wsum csum_partial(const void *buff, int len, __wsum sum); | |
17 | ||
18 | /* | |
19 | * the same as csum_partial, but copies from src while it | |
20 | * checksums | |
21 | * | |
22 | * here even more important to align src and dst on a 32-bit (or even | |
23 | * better 64-bit) boundary | |
24 | */ | |
25 | extern __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum); | |
26 | ||
27 | /* | |
28 | * the same as csum_partial_copy, but copies from user space. | |
29 | * | |
30 | * here even more important to align src and dst on a 32-bit (or even | |
31 | * better 64-bit) boundary | |
32 | */ | |
33 | extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst, | |
34 | int len, __wsum sum, int *csum_err); | |
35 | ||
36 | #define csum_partial_copy_nocheck(src, dst, len, sum) \ | |
37 | csum_partial_copy((src), (dst), (len), (sum)) | |
38 | ||
39 | /* | |
40 | * This is a version of ip_compute_csum() optimized for IP headers, | |
41 | * which always checksum on 4 octet boundaries. | |
42 | */ | |
43 | extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl); | |
44 | ||
45 | /* | |
46 | * Fold a partial checksum | |
47 | */ | |
48 | static inline __sum16 csum_fold(__wsum csum) | |
49 | { | |
50 | u32 sum = (__force u32)csum; | |
51 | sum = (sum & 0xffff) + (sum >> 16); | |
52 | sum = (sum & 0xffff) + (sum >> 16); | |
53 | return (__force __sum16)~sum; | |
54 | } | |
55 | ||
56 | #ifndef csum_tcpudp_nofold | |
57 | /* | |
58 | * computes the checksum of the TCP/UDP pseudo-header | |
59 | * returns a 16-bit checksum, already complemented | |
60 | */ | |
61 | extern __wsum | |
62 | csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len, | |
63 | unsigned short proto, __wsum sum); | |
64 | #endif | |
65 | ||
66 | static inline __sum16 | |
67 | csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len, | |
68 | unsigned short proto, __wsum sum) | |
69 | { | |
70 | return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum)); | |
71 | } | |
72 | ||
73 | /* | |
74 | * this routine is used for miscellaneous IP-like checksums, mainly | |
75 | * in icmp.c | |
76 | */ | |
77 | extern __sum16 ip_compute_csum(const void *buff, int len); | |
78 | ||
79 | #endif /* __ASM_GENERIC_CHECKSUM_H */ |