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 #ifndef csum_partial_copy_nocheck 29 #define csum_partial_copy_nocheck(src, dst, len, sum) \ 30 csum_partial_copy((src), (dst), (len), (sum)) 31 #endif 32 33 #ifndef ip_fast_csum 34 /* 35 * This is a version of ip_compute_csum() optimized for IP headers, 36 * which always checksum on 4 octet boundaries. 37 */ 38 extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl); 39 #endif 40 41 #ifndef csum_fold 42 /* 43 * Fold a partial checksum 44 */ 45 static inline __sum16 csum_fold(__wsum csum) 46 { 47 u32 sum = (__force u32)csum; 48 sum = (sum & 0xffff) + (sum >> 16); 49 sum = (sum & 0xffff) + (sum >> 16); 50 return (__force __sum16)~sum; 51 } 52 #endif 53 54 #ifndef csum_tcpudp_nofold 55 /* 56 * computes the checksum of the TCP/UDP pseudo-header 57 * returns a 16-bit checksum, already complemented 58 */ 59 extern __wsum 60 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, 61 __u8 proto, __wsum sum); 62 #endif 63 64 #ifndef csum_tcpudp_magic 65 static inline __sum16 66 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len, 67 __u8 proto, __wsum sum) 68 { 69 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum)); 70 } 71 #endif 72 73 /* 74 * this routine is used for miscellaneous IP-like checksums, mainly 75 * in icmp.c 76 */ 77 extern __sum16 ip_compute_csum(const void *buff, int len); 78 79 #endif /* __ASM_GENERIC_CHECKSUM_H */ 80