in_cksum_arm.h

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/*      $NetBSD: in_cksum_arm.c,v 1.3 2001/12/08 21:18:50 chris Exp $   */

/*
 * ARM version:
 *
 * Copyright (c) 1997 Mark Brinicome
 * Copyright (c) 1997 Causality Limited
 *
 * Based on the sparc version.
 */

/*
 * Sparc version:
 *
 * Copyright (c) 1995 Zubin Dittia.
 * Copyright (c) 1995 Matthew R. Green.
 * Copyright (c) 1994 Charles M. Hannum.
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)in_cksum.c  8.1 (Berkeley) 6/11/93
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>

/*
 * Checksum routine for Internet Protocol family headers.
 *
 * This routine is very heavily used in the network
 * code and should be modified for each CPU to be as fast as possible.
 *
 * ARM version.
 */

#define ADD64   __asm __volatile("      \n\
        ldmia   %0!, {%2, %3, %4, %5}   \n\
        adds    %1,%7,%2; adcs %1,%1,%3 \n\
        adcs    %1,%1,%4; adcs %1,%1,%5 \n\
        ldmia   %0!, {%2, %3, %4, %5}   \n\
        adcs    %1,%1,%2; adcs %1,%1,%3 \n\
        adcs    %1,%1,%4; adcs %1,%1,%5 \n\
        ldmia   %0!, {%2, %3, %4, %5}   \n\
        adcs    %1,%1,%2; adcs %1,%1,%3 \n\
        adcs    %1,%1,%4; adcs %1,%1,%5 \n\
        ldmia   %0!, {%2, %3, %4, %5}   \n\
        adcs    %1,%1,%2; adcs %1,%1,%3 \n\
        adcs    %1,%1,%4; adcs %1,%1,%5 \n\
        adcs    %1,%1,#0\n"             \
        : "=r" (w), "=r" (sum), "=&r" (tmp1), "=&r" (tmp2), "=&r" (tmp3), "=&r" (tmp4) \
        : "0" (w), "r" (sum)    \
        : "cc")
        
#define ADD32   __asm __volatile("      \n\
        ldmia   %0!, {%2, %3, %4, %5}   \n\
        adds    %1,%7,%2; adcs %1,%1,%3 \n\
        adcs    %1,%1,%4; adcs %1,%1,%5 \n\
        ldmia   %0!, {%2, %3, %4, %5}   \n\
        adcs    %1,%1,%2; adcs %1,%1,%3 \n\
        adcs    %1,%1,%4; adcs %1,%1,%5 \n\
        adcs    %1,%1,#0\n"             \
        : "=r" (w), "=r" (sum), "=&r" (tmp1), "=&r" (tmp2), "=&r" (tmp3), "=&r" (tmp4) \
        : "0" (w), "r" (sum)    \
        : "cc")

#define ADD16   __asm __volatile("      \n\
        ldmia   %0!, {%2, %3, %4, %5}   \n\
        adds    %1,%7,%2; adcs %1,%1,%3 \n\
        adcs    %1,%1,%4; adcs %1,%1,%5 \n\
        adcs    %1,%1,#0\n"             \
        : "=r" (w), "=r" (sum), "=&r" (tmp1), "=&r" (tmp2), "=&r" (tmp3), "=&r" (tmp4) \
        : "0" (w), "r" (sum)    \
        : "cc")

#define ADD8    __asm __volatile("      \n\
        ldmia   %0!, {%2, %3}           \n\
        adds    %1,%5,%2; adcs %1,%1,%3 \n\
        adcs    %1,%1,#0\n"             \
        : "=r" (w), "=r" (sum), "=&r" (tmp1), "=&r" (tmp2)      \
        : "0" (w), "r" (sum)            \
        : "cc" )

#define ADD4    __asm __volatile("      \n\
        ldr     %2,[%0],#4              \n\
        adds    %1,%4,%2                \n\
        adcs    %1,%1,#0\n"             \
        : "=r" (w), "=r" (sum), "=&r" (tmp1) \
        : "0" (w), "r" (sum)            \
        : "cc")

/*#define REDUCE        {sum = (sum & 0xffff) + (sum >> 16);}*/
#define REDUCE  __asm __volatile("      \n\
        mov     %2, #0x00ff             \n\
        orr     %2, %2, #0xff00         \n\
        and     %2, %0, %2              \n\
        add     %0, %2, %0, lsr #16\n"  \
        : "=r" (sum)                    \
        : "0" (sum), "r" (tmp1))

#define ADDCARRY        {if (sum > 0xffff) sum -= 0xffff;}
#define ROL             {sum = sum << 8;}       /* depends on recent REDUCE */
#define ADDBYTE         {ROL; sum += (*w << 8); byte_swapped ^= 1;}
#define ADDSHORT        {sum += *(u_short *)w;}
#define ADVANCE(n)      {w += n; mlen -= n;}
#define ADVANCEML(n)    {mlen -= n;}

static __inline__ int
in_cksum_internal(struct mbuf *m, int off, int len, u_int sum)  
{
        u_char *w;
        int mlen = 0;
        int byte_swapped = 0;

        /*
         * Declare four temporary registers for use by the asm code.  We
         * allow the compiler to pick which specific machine registers to
         * use, instead of hard-coding this in the asm code above.
         */
        register u_int tmp1=0, tmp2, tmp3, tmp4;

        for (; m && len; m = m->m_next) {
                if (m->m_len == 0)
                        continue;
                w = mtod(m, u_char *) + off;
                mlen = m->m_len - off;
                off = 0;
                if (len < mlen)
                        mlen = len;
                len -= mlen;

                /*
                 * Ensure that we're aligned on a word boundary here so
                 * that we can do 32 bit operations below.
                 */
                if ((3 & (long)w) != 0) {
                        REDUCE;
                        if ((1 & (long)w) != 0 && mlen >= 1) {
                                ADDBYTE;
                                ADVANCE(1);
                        }
                        if ((2 & (long)w) != 0 && mlen >= 2) {
                                ADDSHORT;
                                ADVANCE(2);
                        }
                }

                /*
                 * Do as many 32 bit operations as possible using the
                 * 64/32/16/8/4 macro's above, using as many as possible of
                 * these.
                 */

                while (mlen >= 64) {
                        ADD64;
                        ADVANCEML(64);
                }
                if (mlen >= 32) {
                        ADD32;
                        ADVANCEML(32);
                }
                if (mlen >= 16) {
                        ADD16;
                        ADVANCEML(16);
                }
                if (mlen >= 8) {
                        ADD8;
                        ADVANCEML(8);
                }
                if (mlen >= 4) {
                        ADD4;
                        ADVANCEML(4)
                }
                if (mlen == 0)
                        continue;

                REDUCE;
                if (mlen >= 2) {
                        ADDSHORT;
                        ADVANCE(2);
                }
                if (mlen == 1) {
                        ADDBYTE;
                }
        }
        if (byte_swapped) {
                REDUCE;
                ROL;
        }
        REDUCE;
        ADDCARRY;

        return (0xffff ^ sum);
}

int
in_cksum(
    struct mbuf *m,
    int len)
{
    int cksum;
    cksum =in_cksum_internal(m, 0, len, 0);
    return cksum;
}

int
in4_cksum(
    struct mbuf *m,
    u_int8_t nxt,
    int off,
    int len )
{
        u_int sum = 0;
        
        if (nxt != 0) {
            /* for ADD macros */
            register u_int tmp1, tmp2, tmp3, tmp4;
            u_char *w;
            struct ipovly ipov;
            /* pseudo header */
            if (off < sizeof(struct ipovly))
                panic("in4_cksum: offset too short");
            if (m->m_len < sizeof(struct ip))
                panic("in4_cksum: bad mbuf chain");
        
            bzero(&ipov, sizeof(ipov));
            ipov.ih_len = htons(len);
            ipov.ih_pr = nxt;
            ipov.ih_src = mtod(m, struct ip *)->ip_src;
            ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
            w = (u_char *)&ipov;
        
            /* assumes sizeof(ipov) == 20 */
            ADD16;
            ADD4;
        }
        /* skip unnecessary part */
        while (m && off > 0) {
                if (m->m_len > off)
                        break;
                off -= m->m_len;
                m = m->m_next;
        }
        return (in_cksum_internal(m, off, len, sum));
}