1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __ASM_GENERIC_CHECKSUM_H 3 #define __ASM_GENERIC_CHECKSUM_H 4 5 #include <linux/bitops.h> 6 7 /* 8 * computes the checksum of a memory block at buff, length len, 9 * and adds in "sum" (32-bit) 10 * 11 * returns a 32-bit number suitable for feeding into itself 12 * or csum_tcpudp_magic 13 * 14 * this function must be called with even lengths, except 15 * for the last fragment, which may be odd 16 * 17 * it's best to have buff aligned on a 32-bit boundary 18 */ 19 extern __wsum csum_partial(const void *buff, int len, __wsum sum); 20 21 #ifndef ip_fast_csum 22 /* 23 * This is a version of ip_compute_csum() optimized for IP headers, 24 * which always checksum on 4 octet boundaries. 25 */ 26 extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl); 27 #endif 28 29 #ifndef csum_fold 30 /* 31 * Fold a partial checksum 32 */ 33 static inline __sum16 csum_fold(__wsum csum) 34 { 35 u32 sum = (__force u32)csum; 36 return (__force __sum16)((~sum - ror32(sum, 16)) >> 16); 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