checksum.h

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/* checksum.h: FRV checksumming
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#ifndef _ASM_CHECKSUM_H
#define _ASM_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
 */
__wsum csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum 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
 */
extern __wsum csum_partial_copy_from_user(const void __user *src, void *dst,
                        int len, __wsum sum, int *csum_err);

/*
 *  This is a version of ip_compute_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 tmp, inc, sum = 0;

    asm("   addcc       gr0,gr0,gr0,icc0\n" /* clear icc0.C */
        "   subi        %1,#4,%1    \n"
        "0:                 \n"
        "   ldu.p       @(%1,%3),%4 \n"
        "   subicc      %2,#1,%2,icc1   \n"
        "   addxcc.p    %4,%0,%0,icc0   \n"
        "   bhi     icc1,#2,0b  \n"

        /* fold the 33-bit result into 16-bits */
        "   addxcc      gr0,%0,%0,icc0  \n"
        "   srli        %0,#16,%1   \n"
        "   sethi       #0,%0       \n"
        "   add     %1,%0,%0    \n"
        "   srli        %0,#16,%1   \n"
        "   add     %1,%0,%0    \n"

        : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (inc), "=&r"(tmp)
        : "0" (sum), "1" (iph), "2" (ihl), "3" (4),
        "m"(*(volatile struct { int _[100]; } *)iph)
        : "icc0", "icc1", "memory"
        );

    return (__force __sum16)~sum;
}

/*
 *  Fold a partial checksum
 */
static inline __sum16 csum_fold(__wsum sum)
{
    unsigned int tmp;

    asm("   srli        %0,#16,%1   \n"
        "   sethi       #0,%0       \n"
        "   add     %1,%0,%0    \n"
        "   srli        %0,#16,%1   \n"
        "   add     %1,%0,%0    \n"
        : "=r"(sum), "=&r"(tmp)
        : "0"(sum)
        );

    return (__force __sum16)~sum;
}

/*
 * computes the checksum of the TCP/UDP pseudo-header
 * returns a 16-bit checksum, already complemented
 */
static inline __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
          unsigned short proto, __wsum sum)
{
    asm("   addcc       %1,%0,%0,icc0   \n"
        "   addxcc      %2,%0,%0,icc0   \n"
        "   addxcc      %3,%0,%0,icc0   \n"
        "   addxcc      gr0,%0,%0,icc0  \n"
        : "=r" (sum)
        : "r" (daddr), "r" (saddr), "r" (len + proto), "0"(sum)
        : "icc0"
        );
    return sum;
}

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
 */
extern __sum16 ip_compute_csum(const void *buff, int len);

#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)
{
    unsigned long tmp, tmp2;

    asm("   addcc       %2,%0,%0,icc0   \n"

        /* add up the source addr */
        "   ldi     @(%3,0),%1  \n"
        "   addxcc      %1,%0,%0,icc0   \n"
        "   ldi     @(%3,4),%2  \n"
        "   addxcc      %2,%0,%0,icc0   \n"
        "   ldi     @(%3,8),%1  \n"
        "   addxcc      %1,%0,%0,icc0   \n"
        "   ldi     @(%3,12),%2 \n"
        "   addxcc      %2,%0,%0,icc0   \n"

        /* add up the dest addr */
        "   ldi     @(%4,0),%1  \n"
        "   addxcc      %1,%0,%0,icc0   \n"
        "   ldi     @(%4,4),%2  \n"
        "   addxcc      %2,%0,%0,icc0   \n"
        "   ldi     @(%4,8),%1  \n"
        "   addxcc      %1,%0,%0,icc0   \n"
        "   ldi     @(%4,12),%2 \n"
        "   addxcc      %2,%0,%0,icc0   \n"

        /* fold the 33-bit result into 16-bits */
        "   addxcc      gr0,%0,%0,icc0  \n"
        "   srli        %0,#16,%1   \n"
        "   sethi       #0,%0       \n"
        "   add     %1,%0,%0    \n"
        "   srli        %0,#16,%1   \n"
        "   add     %1,%0,%0    \n"

        : "=r" (sum), "=&r" (tmp), "=r" (tmp2)
        : "r" (saddr), "r" (daddr), "0" (sum), "2" (len + proto)
        : "icc0"
        );

    return (__force __sum16)~sum;
}

#endif /* _ASM_CHECKSUM_H */