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 */ 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 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