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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_14_fg_14_08.vhd,v 1.2 2001-10-26 16:29:35 paw Exp $
-- $Revision: 1.2 $
--
-- ---------------------------------------------------------------------
library ieee; use ieee.std_logic_1164.all;
entity buf is
port ( a : in std_logic; y : out std_logic );
end entity buf;
architecture basic of buf is
begin
y <= a;
end architecture basic;
-- code from book
library ieee; use ieee.std_logic_1164.all;
entity fanout_tree is
generic ( height : natural );
port ( input : in std_logic;
output : out std_logic_vector (0 to 2**height - 1) );
end entity fanout_tree;
--------------------------------------------------
architecture recursive of fanout_tree is
begin
degenerate_tree : if height = 0 generate
begin
output(0) <= input;
end generate degenerate_tree;
compound_tree : if height > 0 generate
signal buffered_input_0, buffered_input_1 : std_logic;
begin
buf_0 : entity work.buf(basic)
port map ( a => input, y => buffered_input_0 );
subtree_0 : entity work.fanout_tree(recursive)
generic map ( height => height - 1 )
port map ( input => buffered_input_0,
output => output(0 to 2**(height - 1) - 1) );
buf_1 : entity work.buf(basic)
port map ( a => input, y => buffered_input_1 );
subtree_1 : entity work.fanout_tree(recursive)
generic map ( height => height - 1 )
port map ( input => buffered_input_1,
output => output(2**(height - 1) to 2**height - 1) );
end generate compound_tree;
end architecture recursive;
-- end code from book
library ieee; use ieee.std_logic_1164.all;
entity fg_14_08 is
end entity fg_14_08;
architecture test of fg_14_08 is
signal unbuffered_clock : std_logic;
signal buffered_clock_array : std_logic_vector(0 to 7);
begin
-- code from book (in text)
clock_buffer_tree : entity work.fanout_tree(recursive)
generic map ( height => 3 )
port map ( input => unbuffered_clock,
output => buffered_clock_array );
-- end code from book
clock_gen : process is
begin
unbuffered_clock <= '1' after 5 ns, '0' after 10 ns;
wait for 10 ns;
end process clock_gen;
end architecture test;
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