/*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		Checksumming functions for IP, TCP, UDP and so on
   *
   * Authors:	Jorge Cwik, <jorge@laser.satlink.net>
   *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
   *		Borrows very liberally from tcp.c and ip.c, see those
   *		files for more names.
   *
   *		This program is free software; you can redistribute it and/or
   *		modify it under the terms of the GNU General Public License
   *		as published by the Free Software Foundation; either version
   *		2 of the License, or (at your option) any later version.
   */
  
  #ifndef _CHECKSUM_H
  #define _CHECKSUM_H
  
  #include <linux/errno.h>
  #include <asm/types.h>
  #include <asm/byteorder.h>
  #include <asm/uaccess.h>
  #include <asm/checksum.h>
  
  #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
  static inline

  __wsum csum_and_copy_from_user (const void __user *src, void *dst,
  				      int len, __wsum sum, int *err_ptr)

  {
  	if (access_ok(VERIFY_READ, src, len))
  		return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
  
  	if (len)
  		*err_ptr = -EFAULT;
  
  	return sum;
  }
  #endif
  
  #ifndef HAVE_CSUM_COPY_USER

  static __inline__ __wsum csum_and_copy_to_user
  (const void *src, void __user *dst, int len, __wsum sum, int *err_ptr)

  {
  	sum = csum_partial(src, len, sum);
  
  	if (access_ok(VERIFY_WRITE, dst, len)) {
  		if (copy_to_user(dst, src, len) == 0)
  			return sum;
  	}
  	if (len)
  		*err_ptr = -EFAULT;

  	return (__force __wsum)-1; /* invalid checksum */

  }
  #endif

  static inline __wsum csum_add(__wsum csum, __wsum addend)

  {

  	u32 res = (__force u32)csum;
  	res += (__force u32)addend;
  	return (__force __wsum)(res + (res < (__force u32)addend));

  }

  static inline __wsum csum_sub(__wsum csum, __wsum addend)

  {
  	return csum_add(csum, ~addend);
  }

  static inline __wsum
  csum_block_add(__wsum csum, __wsum csum2, int offset)

  {

  	u32 sum = (__force u32)csum2;

  	if (offset&1)

  		sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
  	return csum_add(csum, (__force __wsum)sum);

  }

  static inline __wsum
  csum_block_sub(__wsum csum, __wsum csum2, int offset)

  {

  	u32 sum = (__force u32)csum2;

  	if (offset&1)

  		sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
  	return csum_sub(csum, (__force __wsum)sum);
  }
  
  static inline __wsum csum_unfold(__sum16 n)
  {
  	return (__force __wsum)n;

  }

  #define CSUM_MANGLED_0 ((__force __sum16)0xffff)

  #endif