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-- Copyright 2015, Jürgen Defurne

--

-- This file is part of the Experimental Unstable CPU System.

--

-- The Experimental Unstable CPU System Is free software: you can redistribute

-- it and/or modify it under the terms of the GNU Lesser General Public License

-- as published by the Free Software Foundation, either version 3 of the

-- License, or (at your option) any later version.

--

-- The Experimental Unstable CPU System 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 Lesser

-- General Public License for more details.

--

-- You should have received a copy of the GNU Lesser General Public License

-- along with Experimental Unstable CPU System. If not, see

-- http://www.gnu.org/licenses/lgpl.txt.

LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

USE IEEE.numeric_std.ALL;

ENTITY boole IS

  PORT (

    A   : IN  STD_LOGIC_VECTOR(15 DOWNTO 0);

    B   : IN  STD_LOGIC_VECTOR(15 DOWNTO 0);

    X   : OUT STD_LOGIC_VECTOR(15 DOWNTO 0);

    SEL : IN  STD_LOGIC_VECTOR(3 DOWNTO 0));

END boole;

ARCHITECTURE dataflow OF boole IS

  SIGNAL product : STD_LOGIC_VECTOR(31 DOWNTO 0);

BEGIN  -- dataflow

  product <= STD_LOGIC_VECTOR(UNSIGNED(A) * UNSIGNED(B));

  WITH SEL SELECT

    X <=

    A        WHEN "0000",

    NOT A    WHEN "0001",

    B        WHEN "0010",

    NOT B    WHEN "0011",

    A AND B  WHEN "0100",

    A OR B   WHEN "0101",

    A NAND B WHEN "0110",

    A NOR B  WHEN "0111",

    A XOR B  WHEN "1000",

    A XNOR B WHEN "1001",

    STD_LOGIC_VECTOR(unsigned(A) + unsigned(B)) WHEN "1010",

    STD_LOGIC_VECTOR(unsigned(A) - unsigned(B)) WHEN "1011",

    product(15 DOWNTO 0) WHEN "1100",

    product(31 DOWNTO 16) WHEN "1101",

    A(0) & A(15 DOWNTO 1) WHEN "1110",

    A(14 DOWNTO 0) & A(15) WHEN "1111";

END dataflow;