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-- Copyright (C) 1996 Morgan Kaufmann Publishers, Inc
-- This file is part of VESTs (Vhdl tESTs).
-- VESTs is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at
-- your option) any later version.
-- VESTs is distributed in the hope that it will be useful, but WITHOUT
-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
-- for more details.
-- You should have received a copy of the GNU General Public License
-- along with VESTs; if not, write to the Free Software Foundation,
-- Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-- ---------------------------------------------------------------------
--
-- $Id: ch_07_fg_07_18.vhd,v 1.2 2001-10-26 16:29:34 paw Exp $
-- $Revision: 1.2 $
--
-- ---------------------------------------------------------------------
entity fg_07_18 is
end entity fg_07_18;
architecture test of fg_07_18 is
constant target_host_id : natural := 10;
constant my_host_id : natural := 5;
type pkt_types is (control_pkt, other_pkt);
type pkt_header is record
dest, src : natural;
pkt_type : pkt_types;
seq : natural;
end record;
begin
-- code from book
network_driver : process is
constant seq_modulo : natural := 2**5;
subtype seq_number is natural range 0 to seq_modulo-1;
variable next_seq_number : seq_number := 0;
-- . . .
-- not in book
variable new_header : pkt_header;
-- end not in book
impure function generate_seq_number return seq_number is
variable number : seq_number;
begin
number := next_seq_number;
next_seq_number := (next_seq_number + 1) mod seq_modulo;
return number;
end function generate_seq_number;
begin -- network_driver
-- not in book
wait for 10 ns;
-- end not in book
-- . . .
new_header := pkt_header'( dest => target_host_id,
src => my_host_id,
pkt_type => control_pkt,
seq => generate_seq_number );
-- . . .
end process network_driver;
-- end code from book
end architecture test;
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