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kernel/linux-imx6_3.14.28/arch/ia64/lib/checksum.c 2.54 KB
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  /*
   * Network checksum routines
   *
   * Copyright (C) 1999, 2003 Hewlett-Packard Co
   *	Stephane Eranian <eranian@hpl.hp.com>
   *
   * Most of the code coming from arch/alpha/lib/checksum.c
   *
   * This file contains network checksum routines that are better done
   * in an architecture-specific manner due to speed..
   */
  
  #include <linux/module.h>
  #include <linux/string.h>
  
  #include <asm/byteorder.h>
  
  static inline unsigned short
  from64to16 (unsigned long x)
  {
  	/* add up 32-bit words for 33 bits */
  	x = (x & 0xffffffff) + (x >> 32);
  	/* add up 16-bit and 17-bit words for 17+c bits */
  	x = (x & 0xffff) + (x >> 16);
  	/* add up 16-bit and 2-bit for 16+c bit */
  	x = (x & 0xffff) + (x >> 16);
  	/* add up carry.. */
  	x = (x & 0xffff) + (x >> 16);
  	return x;
  }
  
  /*
   * computes the checksum of the TCP/UDP pseudo-header
   * returns a 16-bit checksum, already complemented.
   */
  __sum16
  csum_tcpudp_magic (__be32 saddr, __be32 daddr, unsigned short len,
  		   unsigned short proto, __wsum sum)
  {
  	return (__force __sum16)~from64to16(
  		(__force u64)saddr + (__force u64)daddr +
  		(__force u64)sum + ((len + proto) << 8));
  }
  
  EXPORT_SYMBOL(csum_tcpudp_magic);
  
  __wsum
  csum_tcpudp_nofold (__be32 saddr, __be32 daddr, unsigned short len,
  		    unsigned short proto, __wsum sum)
  {
  	unsigned long result;
  
  	result = (__force u64)saddr + (__force u64)daddr +
  		 (__force u64)sum + ((len + proto) << 8);
  
  	/* Fold down to 32-bits so we don't lose in the typedef-less network stack.  */
  	/* 64 to 33 */
  	result = (result & 0xffffffff) + (result >> 32);
  	/* 33 to 32 */
  	result = (result & 0xffffffff) + (result >> 32);
  	return (__force __wsum)result;
  }
  EXPORT_SYMBOL(csum_tcpudp_nofold);
  
  extern unsigned long do_csum (const unsigned char *, long);
  
  /*
   * computes the checksum of a memory block at buff, length len,
   * and adds in "sum" (32-bit)
   *
   * returns a 32-bit number suitable for feeding into itself
   * or csum_tcpudp_magic
   *
   * this function must be called with even lengths, except
   * for the last fragment, which may be odd
   *
   * it's best to have buff aligned on a 32-bit boundary
   */
  __wsum csum_partial(const void *buff, int len, __wsum sum)
  {
  	u64 result = do_csum(buff, len);
  
  	/* add in old sum, and carry.. */
  	result += (__force u32)sum;
  	/* 32+c bits -> 32 bits */
  	result = (result & 0xffffffff) + (result >> 32);
  	return (__force __wsum)result;
  }
  
  EXPORT_SYMBOL(csum_partial);
  
  /*
   * this routine is used for miscellaneous IP-like checksums, mainly
   * in icmp.c
   */
  __sum16 ip_compute_csum (const void *buff, int len)
  {
  	return (__force __sum16)~do_csum(buff,len);
  }
  
  EXPORT_SYMBOL(ip_compute_csum);