From owner-freebsd-net  Wed Nov 15  4: 8: 3 2000
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Message-ID: <3A127C7A.8B8DAA13@elischer.org>
Date: Wed, 15 Nov 2000 04:07:22 -0800
From: Julian Elischer <julian@elischer.org>
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To: Ruslan Ermilov <ru@FreeBSD.ORG>,
	Charles Mott <cmott@scientech.com>,
	Archie Cobbs <archie@dellroad.org>, net@FreeBSD.ORG,
	Ari Suutari <ari@suutari.iki.fi>
Subject: Re: libalias: Incremental Update of Internet Checksum
References: <Pine.BSF.4.21.0011122254240.50684-100000@carcassonne.scientech.com> <Pine.BSF.4.21.0011130015100.50906-100000@carcassonne.scientech.com> <20001113103852.E34671@sunbay.com> <3A126F63.8EB0D49@elischer.org>
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Julian Elischer wrote:
uggggh  it reformatted it..
obviously the slashes are at the END of the previouse lines!

> 
> Ruslan Ermilov wrote:
> >
> Here's the version I wrote some years ago..
>   #define FIXSUM16(c, op, np)
> \
>     do {
> \
>       (c) -= (u_int16_t) ~*((u_int16_t *) (op));
> \
>       if ((c) < 0) {
> \
>         (c) += 0xffff;
> \
>       }
> \
>       (c) -= (u_int16_t)  *((u_int16_t *) (np));
> \
>       if ((c) < 0) {
> \
>         (c) += 0xffff;
> \
>       }
> \
>     } while (0)
> 
> it replaces the 16 bit word at *op with the new value at *np and updates
> the
> checksum c
> 
> --
>       __--_|\  Julian Elischer
>      /       \ julian@elischer.org
>     (   OZ    ) World tour 2000
> ---> X_.---._/  presently in:  Budapest
>             v
> 
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-- 
      __--_|\  Julian Elischer
     /       \ julian@elischer.org
    (   OZ    ) World tour 2000
---> X_.---._/  presently in:  Budapest
            v


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