1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_GENERIC_CHECKSUM_H
3 #define __ASM_GENERIC_CHECKSUM_H
4 
5 /*
6  * computes the checksum of a memory block at buff, length len,
7  * and adds in "sum" (32-bit)
8  *
9  * returns a 32-bit number suitable for feeding into itself
10  * or csum_tcpudp_magic
11  *
12  * this function must be called with even lengths, except
13  * for the last fragment, which may be odd
14  *
15  * it's best to have buff aligned on a 32-bit boundary
16  */
17 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
18 
19 /*
20  * the same as csum_partial, but copies from src while it
21  * checksums
22  *
23  * here even more important to align src and dst on a 32-bit (or even
24  * better 64-bit) boundary
25  */
26 extern __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum);
27 
28 /*
29  * the same as csum_partial_copy, but copies from user space.
30  *
31  * here even more important to align src and dst on a 32-bit (or even
32  * better 64-bit) boundary
33  */
34 extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
35 					int len, __wsum sum, int *csum_err);
36 
37 #ifndef csum_partial_copy_nocheck
38 #define csum_partial_copy_nocheck(src, dst, len, sum)	\
39 	csum_partial_copy((src), (dst), (len), (sum))
40 #endif
41 
42 #ifndef ip_fast_csum
43 /*
44  * This is a version of ip_compute_csum() optimized for IP headers,
45  * which always checksum on 4 octet boundaries.
46  */
47 extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
48 #endif
49 
50 #ifndef csum_fold
51 /*
52  * Fold a partial checksum
53  */
54 static inline __sum16 csum_fold(__wsum csum)
55 {
56 	u32 sum = (__force u32)csum;
57 	sum = (sum & 0xffff) + (sum >> 16);
58 	sum = (sum & 0xffff) + (sum >> 16);
59 	return (__force __sum16)~sum;
60 }
61 #endif
62 
63 #ifndef csum_tcpudp_nofold
64 /*
65  * computes the checksum of the TCP/UDP pseudo-header
66  * returns a 16-bit checksum, already complemented
67  */
68 extern __wsum
69 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
70 		   __u8 proto, __wsum sum);
71 #endif
72 
73 #ifndef csum_tcpudp_magic
74 static inline __sum16
75 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
76 		  __u8 proto, __wsum sum)
77 {
78 	return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
79 }
80 #endif
81 
82 /*
83  * this routine is used for miscellaneous IP-like checksums, mainly
84  * in icmp.c
85  */
86 extern __sum16 ip_compute_csum(const void *buff, int len);
87 
88 #endif /* __ASM_GENERIC_CHECKSUM_H */
89