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 #ifndef csum_partial_copy_nocheck
37 #define csum_partial_copy_nocheck(src, dst, len, sum) \
38 csum_partial_copy((src), (dst), (len), (sum))
39 #endif
40
41 /*
42 * This is a version of ip_compute_csum() optimized for IP headers,
43 * which always checksum on 4 octet boundaries.
44 */
45 extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
46
47 /*
48 * Fold a partial checksum
49 */
csum_fold(__wsum csum)50 static inline __sum16 csum_fold(__wsum csum)
51 {
52 u32 sum = (__force u32)csum;
53 sum = (sum & 0xffff) + (sum >> 16);
54 sum = (sum & 0xffff) + (sum >> 16);
55 return (__force __sum16)~sum;
56 }
57
58 #ifndef csum_tcpudp_nofold
59 /*
60 * computes the checksum of the TCP/UDP pseudo-header
61 * returns a 16-bit checksum, already complemented
62 */
63 extern __wsum
64 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
65 unsigned short proto, __wsum sum);
66 #endif
67
68 #ifndef csum_tcpudp_magic
69 static inline __sum16
csum_tcpudp_magic(__be32 saddr,__be32 daddr,unsigned short len,unsigned short proto,__wsum sum)70 csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
71 unsigned short proto, __wsum sum)
72 {
73 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
74 }
75 #endif
76
77 /*
78 * this routine is used for miscellaneous IP-like checksums, mainly
79 * in icmp.c
80 */
81 extern __sum16 ip_compute_csum(const void *buff, int len);
82
83 #endif /* __ASM_GENERIC_CHECKSUM_H */
84