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