CristalCaveGem » LustreC » Lustrec-Tests

-- 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_13_fg_13_14.vhd,v 1.1.1.1 2001-08-22 18:20:48 paw Exp $

-- $Revision: 1.1.1.1 $

--

-- ---------------------------------------------------------------------

entity decoder_3_to_8 is

  generic ( Tpd_01, Tpd_10 : delay_length );

  port ( s0, s1, s2 : in bit;

         enable : in bit;

         y0, y1, y2, y3, y4, y5, y6, y7 : out bit );

end entity decoder_3_to_8;

-- not in book

architecture basic of decoder_3_to_8 is

    subtype bv_vec3 is bit_vector (2 downto 0);

begin

  process (enable, s2, s1, s0) is

  begin

    if enable = '0' then

      (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("00000000");

    else

      case bv_vec3'(s2, s1, s0) is

        when "000" => (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("00000001");

        when "001" => (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("00000010");

        when "010" => (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("00000100");

        when "011" => (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("00001000");

        when "100" => (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("00010000");

        when "101" => (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("00100000");

        when "110" => (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("01000000");

        when "111" => (y7, y6, y5, y4, y3, y2, y1, y0) <= bit_vector'("10000000");

      end case;

    end if;

  end process;

end architecture basic;

-- end not in book