root/arch/ia64/lib/checksum.c

DEFINITIONS

1. from64to16
2. csum_tcpudp_magic
3. csum_tcpudp_nofold
4. csum_partial
5. ip_compute_csum

   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 
  19 static inline unsigned short
  20 from64to16 (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
  38 csum_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 
  46 EXPORT_SYMBOL(csum_tcpudp_magic);
  47 
  48 __wsum
  49 csum_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 }
  64 EXPORT_SYMBOL(csum_tcpudp_nofold);
  65 
  66 extern 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 
  91 EXPORT_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 
 102 EXPORT_SYMBOL(ip_compute_csum);