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

     /*
      * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
      * 
      * This code is derived from software contributed to The DragonFly Project
      * by Matthew Dillon <dillon@backplane.com>
      * 
      * 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. Neither the name of The DragonFly Project 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 COPYRIGHT HOLDERS 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
     * COPYRIGHT HOLDERS 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.
     * 
     *      (note: completely rewritten for DragonFly)
     *
     *      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: src/sys/i386/include/in_cksum.h,v 1.7.2.2 2002/07/02 04:03:04 jdp Exp $
     */
    
    #ifndef _SYS_IN_CKSUM_H_
    #define _SYS_IN_CKSUM_H_
    
    #ifndef _SYS_TYPES_H_
    #include <sys/types.h>
    #endif
    #include <machine/stdint.h>
    
    #ifdef _KERNEL
    
    struct ip;
    struct mbuf;
    
    __uint32_t in_cksum_range(struct mbuf *m, int nxt, int offset, int bytes);
    __uint32_t asm_ones32(const void *buf, int count);      /* in 32 bit words */
    
    static __inline u_int
    in_cksum(struct mbuf *m, int len)
    {
        return(in_cksum_range(m, 0, 0, len));
    }
    
    static __inline u_int
    in_cksum_skip(struct mbuf *m, int len, int skip)
    {
        return(in_cksum_range(m, 0, skip, len - skip));
    }
    
    static __inline u_int
    in_cksum_hdr(const struct ip *ip)
    {
        __uint32_t sum;
    
        sum = asm_ones32((const void *)ip, 5);      /* 5x4 = 20 bytes */
        sum = (sum >> 16) + (sum & 0xFFFF);
        if (sum > 0xFFFF)
            ++sum;
        return(~sum & 0xFFFF);
    }
    
    #endif
    
    static __inline u_short
    in_addword(u_short sum, u_short b)
    {
        /* __volatile is necessary because the condition codes are used. */
        __asm __volatile ("addw %1, %0; adcw $0,%0" : "+r" (sum) : "r" (b));
    
        return (sum);
    }
    
    static __inline u_short
    in_pseudo(u_int sum, u_int b, u_int c)
    {
        /* __volatile is necessary because the condition codes are used. */
        __asm __volatile ("addl %1,%0; adcl %2,%0; adcl $0,%0" 
                            : "+r" (sum) 
                            : "g" (b), "g" (c));
       sum = (sum & 0xffff) + (sum >> 16);
       if (sum > 0xffff)
           sum -= 0xffff;
       return (sum);
   }
   
   #endif /* _MACHINE_IN_CKSUM_H_ */

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