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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 */
17extern __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 */
26extern __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 */
34extern __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 */
47extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
48#endif
49
50#ifndef csum_fold
51/*
52 * Fold a partial checksum
53 */
54static 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 */
68extern __wsum
69csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
70 __u8 proto, __wsum sum);
71#endif
72
73#ifndef csum_tcpudp_magic
74static inline __sum16
75csum_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 */
86extern __sum16 ip_compute_csum(const void *buff, int len);
87
88#endif /* __ASM_GENERIC_CHECKSUM_H */