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#ifndef _I386_CHECKSUM_H

#define _I386_CHECKSUM_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

 */

unsigned int csum_partial(const unsigned char * buff, int len, unsigned int 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

 */

unsigned int csum_partial_copy( const char *src, char *dst, int len, int sum);

/*

 * the same as csum_partial_copy, but copies from user space.

 *

 * here even more important to align src and dst on a 32-bit (or even

 * better 64-bit) boundary

 */

unsigned int csum_partial_copy_fromuser(const char *src, char *dst, int len, int 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 unsigned short ip_fast_csum(unsigned char * iph,

                                          unsigned int ihl) {

        unsigned int sum;

        __asm__ __volatile__("

            movl (%1), %0

            subl $4, %2

            jbe 2f

            addl 4(%1), %0

            adcl 8(%1), %0

            adcl 12(%1), %0

1:          adcl 16(%1), %0

            lea 4(%1), %1

            decl %2

            jne 1b

            adcl $0, %0

            movl %0, %2

            shrl $16, %0

            addw %w2, %w0

            adcl $0, %0

            notl %0

2:

            "

        /* Since the input registers which are loaded with iph and ipl

           are modified, we must also specify them as outputs, or gcc

           will assume they contain their original values. */

        : "=r" (sum), "=r" (iph), "=r" (ihl)

        : "1" (iph), "2" (ihl));

        return(sum);

}

/*

 *      Fold a partial checksum

 */

static inline unsigned int csum_fold(unsigned int sum)

{

        __asm__("

                addl %1, %0

                adcl $0xffff, %0

                "

                : "=r" (sum)

                : "r" (sum << 16), "0" (sum & 0xffff0000)

        );

        return (~sum) >> 16;

}

/*

 * computes the checksum of the TCP/UDP pseudo-header

 * returns a 16-bit checksum, already complemented

 */

static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,

                                                   unsigned long daddr,

                                                   unsigned short len,

                                                   unsigned short proto,

                                                   unsigned int sum) {

    __asm__("

        addl %1, %0

        adcl %2, %0

        adcl %3, %0

        adcl $0, %0

        "

        : "=r" (sum)

        : "g" (daddr), "g"(saddr), "g"((ntohs(len)<<16)+proto*256), "0"(sum));

        return csum_fold(sum);

}

/*

 * this routine is used for miscellaneous IP-like checksums, mainly

 * in icmp.c

 */

static inline unsigned short ip_compute_csum(unsigned char * buff, int len) {

    return csum_fold (csum_partial(buff, len, 0));

}

#endif