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checksum_32.h

#ifndef __ASM_SH_CHECKSUM_H
#define __ASM_SH_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) 1999 by Kaz Kojima & Niibe Yutaka
 */

#include <linux/in6.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__("swap.w %0, %1\n\t"
            "extu.w     %0, %0\n\t"
            "extu.w     %1, %1\n\t"
            "add  %1, %0\n\t"
            "swap.w     %0, %1\n\t"
            "add  %1, %0\n\t"
            "not  %0, %0\n\t"
            : "=r" (sum), "=&r" (__dummy)
            : "0" (sum)
            : "t");
      return (__force __sum16)sum;
}

/*
 *    This is a version of ip_compute_csum() optimized for IP headers,
 *    which always checksum on 4 octet boundaries.
 *
 *      i386 version by Jorge Cwik <jorge@laser.satlink.net>, adapted
 *      for linux by * Arnt Gulbrandsen.
 */
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
      unsigned int sum, __dummy0, __dummy1;

      __asm__ __volatile__(
            "mov.l      @%1+, %0\n\t"
            "mov.l      @%1+, %3\n\t"
            "add  #-2, %2\n\t"
            "clrt\n\t"
            "1:\t"
            "addc %3, %0\n\t"
            "movt %4\n\t"
            "mov.l      @%1+, %3\n\t"
            "dt   %2\n\t"
            "bf/s 1b\n\t"
            " cmp/eq #1, %4\n\t"
            "addc %3, %0\n\t"
            "addc %2, %0"         /* Here %2 is 0, add carry-bit */
      /* 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" (__dummy0), "=&z" (__dummy1)
      : "1" (iph), "2" (ihl)
      : "t", "memory");

      return      csum_fold(sum);
}

static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
                              unsigned short len,
                              unsigned short proto,
                              __wsum sum)
{
#ifdef __LITTLE_ENDIAN__
      unsigned long len_proto = (proto + len) << 8;
#else
      unsigned long len_proto = proto + len;
#endif
      __asm__("clrt\n\t"
            "addc %0, %1\n\t"
            "addc %2, %1\n\t"
            "addc %3, %1\n\t"
            "movt %0\n\t"
            "add  %1, %0"
            : "=r" (sum), "=r" (len_proto)
            : "r" (daddr), "r" (saddr), "1" (len_proto), "0" (sum)
            : "t");

      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__("clrt\n\t"
            "mov.l      @(0,%2), %1\n\t"
            "addc %1, %0\n\t"
            "mov.l      @(4,%2), %1\n\t"
            "addc %1, %0\n\t"
            "mov.l      @(8,%2), %1\n\t"
            "addc %1, %0\n\t"
            "mov.l      @(12,%2), %1\n\t"
            "addc %1, %0\n\t"
            "mov.l      @(0,%3), %1\n\t"
            "addc %1, %0\n\t"
            "mov.l      @(4,%3), %1\n\t"
            "addc %1, %0\n\t"
            "mov.l      @(8,%3), %1\n\t"
            "addc %1, %0\n\t"
            "mov.l      @(12,%3), %1\n\t"
            "addc %1, %0\n\t"
            "addc %4, %0\n\t"
            "addc %5, %0\n\t"
            "movt %1\n\t"
            "add  %1, %0\n"
            : "=r" (sum), "=&r" (__dummy)
            : "r" (saddr), "r" (daddr),
              "r" (htonl(len)), "r" (htonl(proto)), "0" (sum)
            : "t");

      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((__force const void *)src,
                                    dst, len, sum, NULL, err_ptr);

      if (len)
            *err_ptr = -EFAULT;

      return (__force __wsum)-1; /* invalid checksum */
}
#endif /* __ASM_SH_CHECKSUM_H */

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