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/*

 * include/asm-mips/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) 1995 by Ralf Baechle

 */

#ifndef __ASM_MIPS_CHECKSUM_H

#define __ASM_MIPS_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, but copies from user space (but on the alpha

 * we have just one address space, so this is identical to the above)

 */

#define csum_partial_copy_fromuser csum_partial_copy

/*

 *      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 short int sum;

        unsigned long   dummy1, dummy2;

        /*

         * This is optimized for 32-bit MIPS processors.

         * I tried it in plain C but the generated code looks to bad to

         * use with old first generation MIPS CPUs.

         * Using 64-bit code could even further improve these routines.

         */

        __asm__("

        .set    noreorder

        .set    noat

        lw      %0,(%3)

        subu    %1,4

        blez    %1,2f

        sll     %1,%4,2                 # delay slot

        lw      %2,4(%3)

        addu    %1,%3                   # delay slot

        addu    %0,%2

        sltu    $1,%0,%2

        lw      %2,8(%3)

        addu    %0,$1

        addu    %0,%2

        sltu    $1,%0,%2

        lw      %2,12(%3)

        addu    %0,$1

        addu    %0,%2

        sltu    $1,%0,%2

        addu    %0,$1

1:      lw      %2,16(%3)

        addu    %1,4

        addu    %0,%2

        sltu    $1,%0,%2

        bne     %1,%3,1b

        addu    %0,$1                   # delay slot

        srl     $1,%0,16

        addu    %0,$1

        sltu    $1,%0,$1

        addu    %0,$1

        nor     %0,$0,%0

        andi    %0,0xffff

2:      .set    at

        .set    reorder"

        : "=r" (sum), "=r" (dummy1), "=r" (dummy2)

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

        : "$1");

        return sum;

}

/*

 * 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__("

        .set    noat

        addu    %0,%2

        sltu    $1,%0,%2

        addu    %0,$1

        addu    %0,%3

        sltu    $1,%0,%3

        addu    %0,$1

        addu    %0,%4

        sltu    $1,%0,%4

        addu    %0,$1

        srl     $1,%0,16

        addu    %0,$1

        sltu    $1,%0,$1

        addu    %0,$1

        nor     %0,$0,%0

        andi    %0,0xffff

        .set    at"

        : "=r" (sum)

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

        : "$1");

        return (unsigned short)sum;

}

/*

 *      Fold a partial checksum without adding pseudo headers

 */

static inline unsigned short int csum_fold(unsigned int sum)

{

    __asm__("

        .set    noat

        srl     $1,%0,16

        addu    %0,$1

        sltu    $1,%0,$1

        nor     %0,$0,%0

        andi    %0,0xffff

        .set    at"

        : "=r"(sum)

        : "0" (sum)

        : "$1");

        return 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) {

    unsigned short int sum;

    __asm__("

        .set    noat

        srl     $1,%0,16

        addu    %0,$1

        sltu    $1,%0,$1

        nor     %0,$0,%0

        andi    %0,0xffff

        .set    at"

        : "=r"(sum)

        : "r" (csum_partial(buff, len, 0))

        : "$1");

        return sum;

}

#endif /* __ASM_MIPS_CHECKSUM_H */