Subversion Repositories mips_fault_tolerant

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-- Company: 

-- Engineer: 

-- 

-- Create Date:    20:00:20 06/19/2012 

-- Design Name: 

-- Module Name:    Ext_sz - Behavioral 

-- Project Name: 

-- Target Devices: 

-- Tool versions: 

-- Description: 

--

-- Dependencies: 

--

-- Revision: 

-- Revision 0.01 - File Created

-- Additional Comments: 

--

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library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

-- Uncomment the following library declaration if using

-- arithmetic functions with Signed or Unsigned values

--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating

-- any Xilinx primitives in this code.

--library UNISIM;

--use UNISIM.VComponents.all;

entity Ext_sz is

port (

      clk : in  STD_LOGIC;

           rst : in  STD_LOGIC;

      immed_addr : in std_logic_vector(15 downto 0);

                Ext_sz_c   : in std_logic;

      Ext_sz     : out std_logic_vector(31 downto 0)

);

end Ext_sz;

architecture Behavioral of Ext_sz is

shared variable Ext_internal : std_logic_vector(31 downto 0);

begin

       process(Ext_sz_c,immed_addr)

                 variable sign_c : std_logic_vector(15 downto 0) := "0000000000000000";

        variable sign_exit : std_logic_vector(31 downto 0) := "00000000000000000000000000000000";

                 begin

                       case Ext_sz_c is

             when '0' =>

                     sign_c(0 downto 0) := immed_addr(15 downto 15);

                                                        for I in 1 to 15 loop

                                                        sign_c(I) := sign_c(0);

                                                        end loop;

                                                        sign_exit(31 downto 16) := sign_c(15 downto 0);

                     sign_exit(15 downto 0) := immed_addr(15 downto 0);

                                 when '1' =>

                                         sign_exit(31 downto 16) := "0000000000000000";

                                                        sign_exit(15 downto 0) := immed_addr(15 downto 0);

             when others => sign_exit := (others =>'0');

             end case;

                       Ext_internal := sign_exit;

                 end process;

                 process(clk,rst)

                 begin

                       if rst = '0' then

                                           Ext_sz  <= (others => '0');

                                 elsif (RISING_EDGE(Clk))then

                                         Ext_sz <= Ext_internal;

             end if;

                 end process;

end Behavioral;