LXR linux/arch/ia64/lib/checksum.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Network checksum routines
   4 *
   5 * Copyright (C) 1999, 2003 Hewlett-Packard Co
   6 *      Stephane Eranian <eranian@hpl.hp.com>
   7 *
   8 * Most of the code coming from arch/alpha/lib/checksum.c
   9 *
  10 * This file contains network checksum routines that are better done
  11 * in an architecture-specific manner due to speed..
  12 */
  13
  14#include <linux/module.h>
  15#include <linux/string.h>
  16
  17#include <asm/byteorder.h>
  18
  19static inline unsigned short
  20from64to16 (unsigned long x)
  21{
  22        /* add up 32-bit words for 33 bits */
  23        x = (x & 0xffffffff) + (x >> 32);
  24        /* add up 16-bit and 17-bit words for 17+c bits */
  25        x = (x & 0xffff) + (x >> 16);
  26        /* add up 16-bit and 2-bit for 16+c bit */
  27        x = (x & 0xffff) + (x >> 16);
  28        /* add up carry.. */
  29        x = (x & 0xffff) + (x >> 16);
  30        return x;
  31}
  32
  33/*
  34 * computes the checksum of the TCP/UDP pseudo-header
  35 * returns a 16-bit checksum, already complemented.
  36 */
  37__sum16
  38csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
  39                  __u8 proto, __wsum sum)
  40{
  41        return (__force __sum16)~from64to16(
  42                (__force u64)saddr + (__force u64)daddr +
  43                (__force u64)sum + ((len + proto) << 8));
  44}
  45
  46EXPORT_SYMBOL(csum_tcpudp_magic);
  47
  48__wsum
  49csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
  50                   __u8 proto, __wsum sum)
  51{
  52        unsigned long result;
  53
  54        result = (__force u64)saddr + (__force u64)daddr +
  55                 (__force u64)sum + ((len + proto) << 8);
  56
  57        /* Fold down to 32-bits so we don't lose in the typedef-less network stack.  */
  58        /* 64 to 33 */
  59        result = (result & 0xffffffff) + (result >> 32);
  60        /* 33 to 32 */
  61        result = (result & 0xffffffff) + (result >> 32);
  62        return (__force __wsum)result;
  63}
  64EXPORT_SYMBOL(csum_tcpudp_nofold);
  65
  66extern unsigned long do_csum (const unsigned char *, long);
  67
  68/*
  69 * computes the checksum of a memory block at buff, length len,
  70 * and adds in "sum" (32-bit)
  71 *
  72 * returns a 32-bit number suitable for feeding into itself
  73 * or csum_tcpudp_magic
  74 *
  75 * this function must be called with even lengths, except
  76 * for the last fragment, which may be odd
  77 *
  78 * it's best to have buff aligned on a 32-bit boundary
  79 */
  80__wsum csum_partial(const void *buff, int len, __wsum sum)
  81{
  82        u64 result = do_csum(buff, len);
  83
  84        /* add in old sum, and carry.. */
  85        result += (__force u32)sum;
  86        /* 32+c bits -> 32 bits */
  87        result = (result & 0xffffffff) + (result >> 32);
  88        return (__force __wsum)result;
  89}
  90
  91EXPORT_SYMBOL(csum_partial);
  92
  93/*
  94 * this routine is used for miscellaneous IP-like checksums, mainly
  95 * in icmp.c
  96 */
  97__sum16 ip_compute_csum (const void *buff, int len)
  98{
  99        return (__force __sum16)~do_csum(buff,len);
 100}
 101
 102EXPORT_SYMBOL(ip_compute_csum);
 103