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 #ifndef ip_fast_csum
20 /*
21 * This is a version of ip_compute_csum() optimized for IP headers,
22 * which always checksum on 4 octet boundaries.
23 */
24 extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
25 #endif
26
27 #ifndef csum_fold
28 /*
29 * Fold a partial checksum
30 */
csum_fold(__wsum csum)31 static inline __sum16 csum_fold(__wsum csum)
32 {
33 u32 sum = (__force u32)csum;
34 sum = (sum & 0xffff) + (sum >> 16);
35 sum = (sum & 0xffff) + (sum >> 16);
36 return (__force __sum16)~sum;
37 }
38 #endif
39
40 #ifndef csum_tcpudp_nofold
41 /*
42 * computes the checksum of the TCP/UDP pseudo-header
43 * returns a 16-bit checksum, already complemented
44 */
45 extern __wsum
46 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
47 __u8 proto, __wsum sum);
48 #endif
49
50 #ifndef csum_tcpudp_magic
51 static inline __sum16
csum_tcpudp_magic(__be32 saddr,__be32 daddr,__u32 len,__u8 proto,__wsum sum)52 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
53 __u8 proto, __wsum sum)
54 {
55 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
56 }
57 #endif
58
59 /*
60 * this routine is used for miscellaneous IP-like checksums, mainly
61 * in icmp.c
62 */
63 extern __sum16 ip_compute_csum(const void *buff, int len);
64
65 #endif /* __ASM_GENERIC_CHECKSUM_H */
66