FreeBSD/Linux Kernel Cross Reference
sys/arm/include/in_cksum.h

     /*-
      * Copyright (c) 1990 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.
     *
     *      from tahoe:     in_cksum.c      1.2     86/01/05
     *      from:           @(#)in_cksum.c  1.3 (Berkeley) 1/19/91
     *      from: Id: in_cksum.c,v 1.8 1995/12/03 18:35:19 bde Exp
     * $FreeBSD: releng/8.4/sys/arm/include/in_cksum.h 156520 2006-03-09 23:33:59Z cognet $
     */
    
    #ifndef _MACHINE_IN_CKSUM_H_
    #define _MACHINE_IN_CKSUM_H_    1
    
    #include <sys/cdefs.h>
    
    #ifdef _KERNEL
    u_short in_cksum(struct mbuf *m, int len);
    u_short in_addword(u_short sum, u_short b);
    u_short in_cksum_skip(struct mbuf *m, int len, int skip);
    u_int do_cksum(const void *, int);
    u_int in_cksum_hdr(const struct ip *);
    
    static __inline u_short
    in_pseudo(u_int sum, u_int b, u_int c)
    {
            __asm __volatile("adds %0, %0, %1\n"
                            "adcs %0, %0, %2\n"
                            "adc %0, %0, #0\n"
                            : "+r" (sum) 
                            : "r" (b), "r" (c));
            sum = (sum & 0xffff) + (sum >> 16);
            if (sum > 0xffff)
                    sum -= 0xffff;
            return (sum);
    }
    
    #endif /* _KERNEL */
    #endif /* _MACHINE_IN_CKSUM_H_ */

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