/*
 * 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) 1995, 96, 97, 98, 99, 2001 by Ralf Baechle
 * Copyright (C) 1999 Silicon Graphics, Inc.
 * Copyright (C) 2001 Thiemo Seufer.
 * Copyright (C) 2002 Maciej W. Rozycki
 */
#ifndef _ASM_CHECKSUM_H
#define _ASM_CHECKSUM_H

#include <linux/in6.h>

#include <asm/uaccess.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);

__wsum __csum_partial_copy_user(const void *src, void *dst,
                                int len, __wsum sum, int *err_ptr);

/*
 * this is a new version of the above that records errors it finds in *errp,
 * but continues and zeros the rest of the buffer.
 */
static inline
__wsum csum_partial_copy_from_user(const void __user *src, void *dst, int len,
                                   __wsum sum, int *err_ptr)
{
        might_fault();
        return __csum_partial_copy_user((__force void *)src, dst,
                                        len, sum, err_ptr);
}

/*
 * 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)
{
        might_fault();
        if (access_ok(VERIFY_WRITE, dst, len))
                return __csum_partial_copy_user(src, (__force void *)dst,
                                                len, sum, err_ptr);
        if (len)
                *err_ptr = -EFAULT;

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

/*
 * the same as csum_partial, but copies from user space (but on MIPS
 * we have just one address space, so this is identical to the above)
 */
__wsum csum_partial_copy_nocheck(const void *src, void *dst,
                                       int len, __wsum sum);

/*
 *      Fold a partial checksum without adding pseudo headers
 */
static inline __sum16 csum_fold(__wsum sum)
{
        __asm__(
        "       .set    push            # csum_fold\n"
        "       .set    noat            \n"
        "       sll     $1, %0, 16      \n"
        "       addu    %0, $1          \n"
        "       sltu    $1, %0, $1      \n"
        "       srl     %0, %0, 16      \n"
        "       addu    %0, $1          \n"
        "       xori    %0, 0xffff      \n"
        "       .set    pop"
        : "=r" (sum)
        : "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.
 *
 *      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)
{
        const unsigned int *word = iph;
        const unsigned int *stop = word + ihl;
        unsigned int csum;
        int carry;

        csum = word[0];
        csum += word[1];
        carry = (csum < word[1]);
        csum += carry;

        csum += word[2];
        carry = (csum < word[2]);
        csum += carry;

        csum += word[3];
        carry = (csum < word[3]);
        csum += carry;

        word += 4;
        do {
                csum += *word;
                carry = (csum < *word);
                csum += carry;
                word++;
        } while (word != stop);

        return csum_fold(csum);
}

static inline __wsum csum_tcpudp_nofold(__be32 saddr,
        __be32 daddr, unsigned short len, unsigned short proto,
        __wsum sum)
{
        __asm__(
        "       .set    push            # csum_tcpudp_nofold\n"
        "       .set    noat            \n"
#ifdef CONFIG_32BIT
        "       addu    %0, %2          \n"
        "       sltu    $1, %0, %2      \n"
        "       addu    %0, $1          \n"

        "       addu    %0, %3          \n"
        "       sltu    $1, %0, %3      \n"
        "       addu    %0, $1          \n"

        "       addu    %0, %4          \n"
        "       sltu    $1, %0, %4      \n"
        "       addu    %0, $1          \n"
#endif
#ifdef CONFIG_64BIT
        "       daddu   %0, %2          \n"
        "       daddu   %0, %3          \n"
        "       daddu   %0, %4          \n"
        "       dsll32  $1, %0, 0       \n"
        "       daddu   %0, $1          \n"
        "       dsra32  %0, %0, 0       \n"
#endif
        "       .set    pop"
        : "=r" (sum)
        : "0" ((__force unsigned long)daddr),
          "r" ((__force unsigned long)saddr),
#ifdef __MIPSEL__
          "r" ((proto + len) << 8),
#else
          "r" (proto + len),
#endif
          "r" ((__force unsigned long)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)
{
        __asm__(
        "       .set    push            # csum_ipv6_magic\n"
        "       .set    noreorder       \n"
        "       .set    noat            \n"
        "       addu    %0, %5          # proto (long in network byte order)\n"
        "       sltu    $1, %0, %5      \n"
        "       addu    %0, $1          \n"

        "       addu    %0, %6          # csum\n"
        "       sltu    $1, %0, %6      \n"
        "       lw      %1, 0(%2)       # four words source address\n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 4(%2)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 8(%2)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 12(%2)      \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 0(%3)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 4(%3)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 8(%3)       \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       lw      %1, 12(%3)      \n"
        "       addu    %0, $1          \n"
        "       addu    %0, %1          \n"
        "       sltu    $1, %0, %1      \n"

        "       addu    %0, $1          # Add final carry\n"
        "       .set    pop"
        : "=r" (sum), "=r" (proto)
        : "r" (saddr), "r" (daddr),
          "0" (htonl(len)), "1" (htonl(proto)), "r" (sum));

        return csum_fold(sum);
}

#endif /* _ASM_CHECKSUM_H */