/*
   * include/asm-xtensa/checksum.h
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 2001 - 2005 Tensilica Inc.
   */
  
  #ifndef _XTENSA_CHECKSUM_H
  #define _XTENSA_CHECKSUM_H
  
  #include <linux/in6.h>
  #include <asm/uaccess.h>
  #include <variant/core.h>
  
  /*
   * 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
   */
  asmlinkage __wsum csum_partial(const void *buff, int len, __wsum sum);
  
  /*
   * the same as csum_partial, but copies from src while it
   * checksums, and handles user-space pointer exceptions correctly, when needed.
   *
   * here even more important to align src and dst on a 32-bit (or even
   * better 64-bit) boundary
   */
  
  asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst,
  					    int len, __wsum sum,
  					    int *src_err_ptr, int *dst_err_ptr);
  
  /*
   *	Note: when you get a NULL pointer exception here this means someone
   *	passed in an incorrect kernel address to one of these functions.
   *
   *	If you use these functions directly please don't forget the access_ok().
   */
  static inline
  __wsum csum_partial_copy_nocheck(const void *src, void *dst,
  					int len, __wsum sum)
  {
  	return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
  }
  
  static inline
  __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
  				   int len, __wsum sum, int *err_ptr)
  {
  	return csum_partial_copy_generic((__force const void *)src, dst,
  					len, sum, err_ptr, NULL);
  }
  
  /*
   *	Fold a partial checksum
   */
  
  static __inline__ __sum16 csum_fold(__wsum sum)
  {
  	unsigned int __dummy;
  	__asm__("extui	%1, %0, 16, 16
  \t"
  		"extui	%0 ,%0, 0, 16
  \t"
  		"add	%0, %0, %1
  \t"
  		"slli	%1, %0, 16
  \t"
  		"add	%0, %0, %1
  \t"
  		"extui	%0, %0, 16, 16
  \t"
  		"neg	%0, %0
  \t"
  		"addi	%0, %0, -1
  \t"
  		"extui	%0, %0, 0, 16
  \t"
  		: "=r" (sum), "=&r" (__dummy)
  		: "0" (sum));
  	return (__force __sum16)sum;
  }
  
  /*
   *	This is a version of ip_compute_csum() optimized for IP headers,
   *	which always checksum on 4 octet boundaries.
   */
  static __inline__ __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  {
  	unsigned int sum, tmp, endaddr;
  
  	__asm__ __volatile__(
  		"sub		%0, %0, %0
  \t"
  #if XCHAL_HAVE_LOOPS
  		"loopgtz	%2, 2f
  \t"
  #else
  		"beqz		%2, 2f
  \t"
  		"slli		%4, %2, 2
  \t"
  		"add		%4, %4, %1
  \t"
  		"0:\t"
  #endif
  		"l32i		%3, %1, 0
  \t"
  		"add		%0, %0, %3
  \t"
  		"bgeu		%0, %3, 1f
  \t"
  		"addi		%0, %0, 1
  \t"
  		"1:\t"
  		"addi		%1, %1, 4
  \t"
  #if !XCHAL_HAVE_LOOPS
  		"blt		%1, %4, 0b
  \t"
  #endif
  		"2:\t"
  	/* Since the input registers which are loaded with iph and ihl
  	   are modified, we must also specify them as outputs, or gcc
  	   will assume they contain their original values. */
  		: "=r" (sum), "=r" (iph), "=r" (ihl), "=&r" (tmp),
  		  "=&r" (endaddr)
  		: "1" (iph), "2" (ihl)
  		: "memory");
  
  	return	csum_fold(sum);
  }
  
  static __inline__ __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
  						   unsigned short len,
  						   unsigned short proto,
  						   __wsum sum)
  {
  
  #ifdef __XTENSA_EL__
  	unsigned long len_proto = (len + proto) << 8;
  #elif defined(__XTENSA_EB__)
  	unsigned long len_proto = len + proto;
  #else
  # error processor byte order undefined!
  #endif
  	__asm__("add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"add	%0, %0, %2
  \t"
  		"bgeu	%0, %2, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"add	%0, %0, %3
  \t"
  		"bgeu	%0, %3, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		: "=r" (sum), "=r" (len_proto)
  		: "r" (daddr), "r" (saddr), "1" (len_proto), "0" (sum));
  	return sum;
  }
  
  /*
   * computes the checksum of the TCP/UDP pseudo-header
   * returns a 16-bit checksum, already complemented
   */
  static __inline__ __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
  						       unsigned short len,
  						       unsigned short proto,
  						       __wsum sum)
  {
  	return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
  }
  
  /*
   * this routine is used for miscellaneous IP-like checksums, mainly
   * in icmp.c
   */
  
  static __inline__ __sum16 ip_compute_csum(const void *buff, int len)
  {
  	return csum_fold (csum_partial(buff, len, 0));
  }
  
  #define _HAVE_ARCH_IPV6_CSUM
  static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
  					  const struct in6_addr *daddr,
  					  __u32 len, unsigned short proto,
  					  __wsum sum)
  {
  	unsigned int __dummy;
  	__asm__("l32i	%1, %2, 0
  \t"
  		"add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"l32i	%1, %2, 4
  \t"
  		"add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"l32i	%1, %2, 8
  \t"
  		"add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"l32i	%1, %2, 12
  \t"
  		"add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"l32i	%1, %3, 0
  \t"
  		"add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"l32i	%1, %3, 4
  \t"
  		"add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"l32i	%1, %3, 8
  \t"
  		"add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"l32i	%1, %3, 12
  \t"
  		"add	%0, %0, %1
  \t"
  		"bgeu	%0, %1, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"add	%0, %0, %4
  \t"
  		"bgeu	%0, %4, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		"add	%0, %0, %5
  \t"
  		"bgeu	%0, %5, 1f
  \t"
  		"addi	%0, %0, 1
  \t"
  		"1:\t"
  		: "=r" (sum), "=&r" (__dummy)
  		: "r" (saddr), "r" (daddr),
  		  "r" (htonl(len)), "r" (htonl(proto)), "0" (sum)
  		: "memory");
  
  	return csum_fold(sum);
  }
  
  /*
   *	Copy and checksum to user
   */
  #define 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)
  {
  	if (access_ok(VERIFY_WRITE, dst, len))
  		return csum_partial_copy_generic(src,dst,len,sum,NULL,err_ptr);
  
  	if (len)
  		*err_ptr = -EFAULT;
  
  	return (__force __wsum)-1; /* invalid checksum */
  }
  #endif