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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 zerof IS
  GENERIC (
    w_data : NATURAL RANGE 1 TO 32 := 16);
  PORT (
    A     : IN  STD_LOGIC_VECTOR(w_data - 1 DOWNTO 0);
    zero  : OUT STD_LOGIC);
END ENTITY zerof;
 
ARCHITECTURE Behavioral OF zerof IS
 
BEGIN  -- Behavioral
 
  -- purpose: Check if A is zero or non zero
  -- type   : combinational
  -- inputs : A
  -- outputs: zero
  TESTZ : PROCESS (A)
  BEGIN  -- PROCESS TESTZ
 
    IF UNSIGNED(A) = to_unsigned(0,w_data) THEN
      zero  <= '1';
    ELSE
      zero  <= '0';
    END IF;
 
  END PROCESS TESTZ;
 
END Behavioral;