include/asm-generic/checksum.h

   1 #ifndef __ASM_GENERIC_CHECKSUM_H
   2 #define __ASM_GENERIC_CHECKSUM_H
   3
   4 /*
   5  * computes the checksum of a memory block at buff, length len,
   6  * and adds in "sum" (32-bit)
   7  *
   8  * returns a 32-bit number suitable for feeding into itself
   9  * or csum_tcpudp_magic
  10  *
  11  * this function must be called with even lengths, except
  12  * for the last fragment, which may be odd
  13  *
  14  * it's best to have buff aligned on a 32-bit boundary
  15  */
  16 extern __wsum csum_partial(const void *buff, int len, __wsum sum);
  17
  18 /*
  19  * the same as csum_partial, but copies from src while it
  20  * checksums
  21  *
  22  * here even more important to align src and dst on a 32-bit (or even
  23  * better 64-bit) boundary
  24  */
  25 extern __wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum);
  26
  27 /*
  28  * the same as csum_partial_copy, but copies from user space.
  29  *
  30  * here even more important to align src and dst on a 32-bit (or even
  31  * better 64-bit) boundary
  32  */
  33 extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
  34                                         int len, __wsum sum, int *csum_err);
  35
  36 #ifndef csum_partial_copy_nocheck
  37 #define csum_partial_copy_nocheck(src, dst, len, sum)   \
  38         csum_partial_copy((src), (dst), (len), (sum))
  39 #endif
  40
  41 #ifndef ip_fast_csum
  42 /*
  43  * This is a version of ip_compute_csum() optimized for IP headers,
  44  * which always checksum on 4 octet boundaries.
  45  */
  46 extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
  47 #endif
  48
  49 #ifndef csum_fold
  50 /*
  51  * Fold a partial checksum
  52  */
  53 static inline __sum16 csum_fold(__wsum csum)
  54 {
  55         u32 sum = (__force u32)csum;
  56         sum = (sum & 0xffff) + (sum >> 16);
  57         sum = (sum & 0xffff) + (sum >> 16);
  58         return (__force __sum16)~sum;
  59 }
  60 #endif
  61
  62 #ifndef csum_tcpudp_nofold
  63 /*
  64  * computes the checksum of the TCP/UDP pseudo-header
  65  * returns a 16-bit checksum, already complemented
  66  */
  67 extern __wsum
  68 csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
  69                    __u8 proto, __wsum sum);
  70 #endif
  71
  72 #ifndef csum_tcpudp_magic
  73 static inline __sum16
  74 csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
  75                   __u8 proto, __wsum sum)
  76 {
  77         return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
  78 }
  79 #endif
  80
  81 /*
  82  * this routine is used for miscellaneous IP-like checksums, mainly
  83  * in icmp.c
  84  */
  85 extern __sum16 ip_compute_csum(const void *buff, int len);
  86
  87 #endif /* __ASM_GENERIC_CHECKSUM_H */