| 1 |
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| 2 | #ifndef __ASM_GENERIC_CHECKSUM_H
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| 3 | #define __ASM_GENERIC_CHECKSUM_H
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| 4 |
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| 5 | #include <linux/bitops.h>
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| 6 |
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| 7 | |
| 8 | * computes the checksum of a memory block at buff, length len,
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| 9 | * and adds in "sum" (32-bit)
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| 10 | *
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| 11 | * returns a 32-bit number suitable for feeding into itself
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| 12 | * or csum_tcpudp_magic
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| 13 | *
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| 14 | * this function must be called with even lengths, except
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| 15 | * for the last fragment, which may be odd
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| 16 | *
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| 17 | * it's best to have buff aligned on a 32-bit boundary
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| 18 |
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| 19 | extern __wsum csum_partial(const void *buff, int len, __wsum sum);
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| 20 |
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| 21 | #ifndef ip_fast_csum
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| 22 | |
| 23 | * This is a version of ip_compute_csum() optimized for IP headers,
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| 24 | * which always checksum on 4 octet boundaries.
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| 25 |
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| 26 | extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
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| 27 | #endif
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| 28 |
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| 29 | #ifndef csum_fold
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| 30 | |
| 31 | * Fold a partial checksum
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| 32 |
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| 33 | static inline __sum16 csum_fold(__wsum csum)
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| 34 | {
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| 35 | u32 sum = (__force u32)csum;
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| 36 | return (__force __sum16)((~sum - ror32(sum, 16)) >> 16);
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| 37 | }
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| 38 | #endif
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| 39 |
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| 40 | #ifndef csum_tcpudp_nofold
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| 41 | |
| 42 | * computes the checksum of the TCP/UDP pseudo-header
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| 43 | * returns a 16-bit checksum, already complemented
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| 44 |
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| 45 | extern __wsum
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| 46 | csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
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| 47 | __u8 proto, __wsum sum);
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| 48 | #endif
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| 49 |
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| 50 | #ifndef csum_tcpudp_magic
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| 51 | static inline __sum16
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| 52 | csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
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| 53 | __u8 proto, __wsum sum)
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| 54 | {
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| 55 | return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
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| 56 | }
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| 57 | #endif
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| 58 |
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| 59 | |
| 60 | * this routine is used for miscellaneous IP-like checksums, mainly
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| 61 | * in icmp.c
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| 62 |
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| 63 | extern __sum16 ip_compute_csum(const void *buff, int len);
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| 64 |
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| 65 | #endif
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