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-- Function: sgnext.vhd - Extends sign bit of half size 
--           data word in into full size data word out.
-- Requires: pkgmips.vhd
-- Author:   
-- Creation: 
-- Verified: 
-- Version:  
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-- entity:  SignExtend  - Extends sign bit
-- port:    n     - Input signal of DHWordSize bits
--          nex   - Output signal of DHWordSize bits
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USE work.mips.all;
library IEEE;
use IEEE.std_logic_1164.all;
ENTITY SignExtend is
    PORT(n : IN std_logic_vector(DHWordSize-1 downto 0);
         nex : OUT std_logic_vector(DWordSize-1 downto 0)
         );
END SignExtend;

ARCHITECTURE behav OF SignExtend IS
BEGIN
    one : PROCESS(n) 
        VARIABLE I: INTEGER;
    BEGIN
        FOR I IN 0 TO DHWordSize - 1 LOOP
            nex(I) <= n(I);
            nex(2*DHWordSize - 1 - I) <= n(3);
        END LOOP;    
    END PROCESS one;
END behav;