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 #ifndef ip_fast_csum
42 /*
43  * This is a version of ip_compute_csum() optimized for IP headers,
44  * which always checksum on 4 octet boundaries.
45  */
46 extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
47 #endif
48 
49 #ifndef csum_fold
50 /*
51  * Fold a partial checksum
52  */
53 static inline __sum16 csum_fold(__wsum csum)
54 {
55 	u32 sum = (__force u32)csum;
56 	sum = (sum & 0xffff) + (sum >> 16);
57 	sum = (sum & 0xffff) + (sum >> 16);
58 	return (__force __sum16)~sum;
59 }
60 #endif
61 
62 #ifndef csum_tcpudp_nofold
63 /*
64  * computes the checksum of the TCP/UDP pseudo-header
65  * returns a 16-bit checksum, already complemented
66  */
67 extern __wsum
68 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
69 		unsigned short proto, __wsum sum);
70 #endif
71 
72 #ifndef csum_tcpudp_magic
73 static inline __sum16
74 csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
75 		  unsigned short proto, __wsum sum)
76 {
77 	return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
78 }
79 #endif
80 
81 /*
82  * this routine is used for miscellaneous IP-like checksums, mainly
83  * in icmp.c
84  */
85 extern __sum16 ip_compute_csum(const void *buff, int len);
86 
87 #endif /* __ASM_GENERIC_CHECKSUM_H */
88