root/include/asm-generic/checksum.h

INCLUDED FROM

DEFINITIONS

1. csum_fold
2. csum_tcpudp_magic

   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 */