pkt

%% Copyright (c) 2009-2015, Michael Santos <michael.santos@gmail.com>
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%% modification, are permitted provided that the following conditions
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%% POSSIBILITY OF SUCH DAMAGE.
-module(pkt_gre).

-include("pkt_ether.hrl").
-include("pkt_gre.hrl").

-export([codec/1]).

codec(<<0:1,Res0:12,Ver:3,Type:16,Rest/binary>>) ->
    {#gre{c = 0, res0 = Res0, ver = Ver, type = Type
       },Rest
    };
codec(<<1:1,Res0:12,Ver:3,Type:16,Chksum:16,Res1:16,Rest/binary>>) ->
    {#gre{c = 1, res0 = Res0, ver = Ver, type = Type,
	chksum = Chksum, res1 = Res1
       },Rest
    };
codec(#gre{c = 0, res0 = Res0, ver = Ver, type = Type}) ->
    <<0:1,Res0:12,Ver:3,Type:16>>;
codec(#gre{c = 1, res0 = Res0, ver = Ver, type = Type,
	chksum = Chksum, res1 = Res1}) ->
    <<1:1,Res0:12,Ver:3,Type:16,Chksum:16,Res1:16>>.