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 #ifndef csum_partial_copy_nocheck 27 __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len, 28 __wsum sum); 29 #endif 30 31 #ifndef ip_fast_csum 32 /* 33 * This is a version of ip_compute_csum() optimized for IP headers, 34 * which always checksum on 4 octet boundaries. 35 */ 36 extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl); 37 #endif 38 39 #ifndef csum_fold 40 /* 41 * Fold a partial checksum 42 */ 43 static inline __sum16 csum_fold(__wsum csum) 44 { 45 u32 sum = (__force u32)csum; 46 sum = (sum & 0xffff) + (sum >> 16); 47 sum = (sum & 0xffff) + (sum >> 16); 48 return (__force __sum16)~sum; 49 } 50 #endif 51 52 #ifndef csum_tcpudp_nofold 53 /* 54 * computes the checksum of the TCP/UDP pseudo-header 55 * returns a 16-bit checksum, already complemented 56 */ 57 extern __wsum 58 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, 59 __u8 proto, __wsum sum); 60 #endif 61 62 #ifndef csum_tcpudp_magic 63 static inline __sum16 64 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, 65 __u8 proto, __wsum sum) 66 { 67 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum)); 68 } 69 #endif 70 71 /* 72 * this routine is used for miscellaneous IP-like checksums, mainly 73 * in icmp.c 74 */ 75 extern __sum16 ip_compute_csum(const void *buff, int len); 76 77 #endif /* __ASM_GENERIC_CHECKSUM_H */ 78