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checksum.h

#ifndef _PARISC_CHECKSUM_H
#define _PARISC_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
 */
extern __wsum csum_partial(const void *, int, __wsum);

/*
 * 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_nocheck(const void *, void *, int, __wsum);

/*
 * this is a new version of the above that records errors it finds in *errp,
 * but continues and zeros the rest of the buffer.
 */
extern __wsum csum_partial_copy_from_user(const void __user *src,
            void *dst, int len, __wsum sum, int *errp);

/*
 *    Optimized for IP headers, which always checksum on 4 octet boundaries.
 *
 *    Written by Randolph Chung <tausq@debian.org>, and then mucked with by
 *    LaMont Jones <lamont@debian.org>
 */
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
      unsigned int sum;

      __asm__ __volatile__ (
"     ldws,ma           4(%1), %0\n"
"     addib,<=    -4, %2, 2f\n"
"\n"
"     ldws        4(%1), %%r20\n"
"     ldws        8(%1), %%r21\n"
"     add         %0, %%r20, %0\n"
"     ldws,ma           12(%1), %%r19\n"
"     addc        %0, %%r21, %0\n"
"     addc        %0, %%r19, %0\n"
"1:   ldws,ma           4(%1), %%r19\n"
"     addib,<           0, %2, 1b\n"
"     addc        %0, %%r19, %0\n"
"\n"
"     extru       %0, 31, 16, %%r20\n"
"     extru       %0, 15, 16, %%r21\n"
"     addc        %%r20, %%r21, %0\n"
"     extru       %0, 15, 16, %%r21\n"
"     add         %0, %%r21, %0\n"
"     subi        -1, %0, %0\n"
"2:\n"
      : "=r" (sum), "=r" (iph), "=r" (ihl)
      : "1" (iph), "2" (ihl)
      : "r19", "r20", "r21", "memory");

      return (__force __sum16)sum;
}

/*
 *    Fold a partial checksum
 */
static inline __sum16 csum_fold(__wsum csum)
{
      u32 sum = (__force u32)csum;
      /* add the swapped two 16-bit halves of sum,
         a possible carry from adding the two 16-bit halves,
         will carry from the lower half into the upper half,
         giving us the correct sum in the upper half. */
      sum += (sum << 16) + (sum >> 16);
      return (__force __sum16)(~sum >> 16);
}
 
static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
                                     unsigned short len,
                                     unsigned short proto,
                                     __wsum sum)
{
      __asm__(
      "     add  %1, %0, %0\n"
      "     addc %2, %0, %0\n"
      "     addc %3, %0, %0\n"
      "     addc %%r0, %0, %0\n"
            : "=r" (sum)
            : "r" (daddr), "r"(saddr), "r"(proto+len), "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 *buf, int len)
{
       return csum_fold (csum_partial(buf, 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)
{
      __asm__ __volatile__ (

#if BITS_PER_LONG > 32

      /*
      ** We can execute two loads and two adds per cycle on PA 8000.
      ** But add insn's get serialized waiting for the carry bit.
      ** Try to keep 4 registers with "live" values ahead of the ALU.
      */

"     ldd,ma            8(%1), %%r19\n"   /* get 1st saddr word */
"     ldd,ma            8(%2), %%r20\n"   /* get 1st daddr word */
"     add         %8, %3, %3\n"/* add 16-bit proto + len */
"     add         %%r19, %0, %0\n"
"     ldd,ma            8(%1), %%r21\n"   /* 2cd saddr */
"     ldd,ma            8(%2), %%r22\n"   /* 2cd daddr */
"     add,dc            %%r20, %0, %0\n"
"     add,dc            %%r21, %0, %0\n"
"     add,dc            %%r22, %0, %0\n"
"     add,dc            %3, %0, %0\n"  /* fold in proto+len | carry bit */
"     extrd,u           %0, 31, 32, %%r19\n"    /* copy upper half down */
"     depdi       0, 31, 32, %0\n"  /* clear upper half */
"     add         %%r19, %0, %0\n"  /* fold into 32-bits */
"     addc        0, %0, %0\n"            /* add carry */

#else

      /*
      ** For PA 1.x, the insn order doesn't matter as much.
      ** Insn stream is serialized on the carry bit here too.
      ** result from the previous operation (eg r0 + x)
      */

"     ldw,ma            4(%1), %%r19\n"   /* get 1st saddr word */
"     ldw,ma            4(%2), %%r20\n"   /* get 1st daddr word */
"     add         %8, %3, %3\n"     /* add 16-bit proto + len */
"     add         %%r19, %0, %0\n"
"     ldw,ma            4(%1), %%r21\n"   /* 2cd saddr */
"     addc        %%r20, %0, %0\n"
"     ldw,ma            4(%2), %%r22\n"   /* 2cd daddr */
"     addc        %%r21, %0, %0\n"
"     ldw,ma            4(%1), %%r19\n"   /* 3rd saddr */
"     addc        %%r22, %0, %0\n"
"     ldw,ma            4(%2), %%r20\n"   /* 3rd daddr */
"     addc        %%r19, %0, %0\n"
"     ldw,ma            4(%1), %%r21\n"   /* 4th saddr */
"     addc        %%r20, %0, %0\n"
"     ldw,ma            4(%2), %%r22\n"   /* 4th daddr */
"     addc        %%r21, %0, %0\n"
"     addc        %%r22, %0, %0\n"
"     addc        %3, %0, %0\n"     /* fold in proto+len, catch carry */

#endif
      : "=r" (sum), "=r" (saddr), "=r" (daddr), "=r" (len)
      : "0" (sum), "1" (saddr), "2" (daddr), "3" (len), "r" (proto)
      : "r19", "r20", "r21", "r22");
      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)
{
      /* code stolen from include/asm-mips64 */
      sum = csum_partial(src, len, sum);
       
      if (copy_to_user(dst, src, len)) {
            *err_ptr = -EFAULT;
            return (__force __wsum)-1;
      }

      return sum;
}

#endif


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