LXR linux/include/asm-generic/checksum.h

   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 */
  17extern __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 */
  26extern __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 */
  34extern __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 */
  47extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
  48#endif
  49
  50#ifndef csum_fold
  51/*
  52 * Fold a partial checksum
  53 */
  54static 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 */
  68extern __wsum
  69csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
  70                   __u8 proto, __wsum sum);
  71#endif
  72
  73#ifndef csum_tcpudp_magic
  74static inline __sum16
  75csum_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 */
  86extern __sum16 ip_compute_csum(const void *buff, int len);
  87
  88#endif /* __ASM_GENERIC_CHECKSUM_H */
  89