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checksum.h

#ifndef _M68K_CHECKSUM_H
#define _M68K_CHECKSUM_H

#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
 */
__wsum csum_partial(const void *buff, int len, __wsum sum);

/*
 * the same as csum_partial, but copies from src while it
 * checksums
 *
 * here even more important to align src and dst on a 32-bit (or even
 * better 64-bit) boundary
 */

extern __wsum csum_partial_copy_from_user(const void __user *src,
                                    void *dst,
                                    int len, __wsum sum,
                                    int *csum_err);

extern __wsum csum_partial_copy_nocheck(const void *src,
                                    void *dst, int len,
                                    __wsum sum);


#ifdef CONFIG_COLDFIRE

/*
 *    The ColdFire cores don't support all the 68k instructions used
 *    in the optimized checksum code below. So it reverts back to using
 *    more standard C coded checksums. The fast checksum code is
 *    significantly larger than the optimized version, so it is not
 *    inlined here.
 */
__sum16 ip_fast_csum(const void *iph, unsigned int ihl);

static inline __sum16 csum_fold(__wsum sum)
{
      unsigned int tmp = (__force u32)sum;

      tmp = (tmp & 0xffff) + (tmp >> 16);
      tmp = (tmp & 0xffff) + (tmp >> 16);

      return (__force __sum16)~tmp;
}

#else

/*
 *    This is a version of ip_fast_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 = 0;
      unsigned long tmp;

      __asm__ ("subqw #1,%2\n"
             "1:\t"
             "movel %1@+,%3\n\t"
             "addxl %3,%0\n\t"
             "dbra  %2,1b\n\t"
             "movel %0,%3\n\t"
             "swap  %3\n\t"
             "addxw %3,%0\n\t"
             "clrw  %3\n\t"
             "addxw %3,%0\n\t"
             : "=d" (sum), "=&a" (iph), "=&d" (ihl), "=&d" (tmp)
             : "0" (sum), "1" (iph), "2" (ihl)
             : "memory");
      return (__force __sum16)~sum;
}

static inline __sum16 csum_fold(__wsum sum)
{
      unsigned int tmp = (__force u32)sum;

      __asm__("swap %1\n\t"
            "addw %1, %0\n\t"
            "clrw %1\n\t"
            "addxw %1, %0"
            : "=&d" (sum), "=&d" (tmp)
            : "0" (sum), "1" (tmp));

      return (__force __sum16)~sum;
}

#endif /* CONFIG_COLDFIRE */

static inline __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
              unsigned short proto, __wsum sum)
{
      __asm__ ("addl  %2,%0\n\t"
             "addxl %3,%0\n\t"
             "addxl %4,%0\n\t"
             "clrl %1\n\t"
             "addxl %1,%0"
             : "=&d" (sum), "=d" (saddr)
             : "g" (daddr), "1" (saddr), "d" (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)
{
      register unsigned long tmp;
      __asm__("addl %2@,%0\n\t"
            "movel %2@(4),%1\n\t"
            "addxl %1,%0\n\t"
            "movel %2@(8),%1\n\t"
            "addxl %1,%0\n\t"
            "movel %2@(12),%1\n\t"
            "addxl %1,%0\n\t"
            "movel %3@,%1\n\t"
            "addxl %1,%0\n\t"
            "movel %3@(4),%1\n\t"
            "addxl %1,%0\n\t"
            "movel %3@(8),%1\n\t"
            "addxl %1,%0\n\t"
            "movel %3@(12),%1\n\t"
            "addxl %1,%0\n\t"
            "addxl %4,%0\n\t"
            "clrl %1\n\t"
            "addxl %1,%0"
            : "=&d" (sum), "=&d" (tmp)
            : "a" (saddr), "a" (daddr), "d" (len + proto),
              "0" (sum));

      return csum_fold(sum);
}

#endif /* _M68K_CHECKSUM_H */

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