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TwoComplementer.vhd
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------------------------------------------------------------------------------
-- This file is a part of the LPP VHDL IP LIBRARY
-- Copyright (C) 2009 - 2010, Laboratory of Plasmas Physic - CNRS
--
-- This program 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 3 of the License, or
-- (at your option) any later version.
--
-- This program 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 this program; if not, write to the Free Software
-- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-------------------------------------------------------------------------------
-- Author : Martin Morlot
-- Mail : martin.morlot@lpp.polytechnique.fr
-------------------------------------------------------------------------------
library IEEE;
use IEEE.numeric_std.all;
use IEEE.std_logic_1164.all;
--! Programme permetant de compl�menter ou non les entr�es de l'ALU, et ainsi de travailler avec des nombres n�gatifs
entity TwoComplementer is
generic(
Input_SZ : integer := 16);
port(
clk : in std_logic; --! Horloge du composant
reset : in std_logic; --! Reset general du composant
clr : in std_logic; --! Un reset sp�cifique au programme
TwoComp : in std_logic; --! Autorise l'utilisation du compl�ment
OP : in std_logic_vector(Input_SZ-1 downto 0); --! Op�rande d'entr�e
RES : out std_logic_vector(Input_SZ-1 downto 0) --! R�sultat, op�rande compl�ment� ou non
);
end TwoComplementer;
architecture ar_TwoComplementer of TwoComplementer is
signal REG : std_logic_vector(Input_SZ-1 downto 0);
signal OPinteger : integer;
signal RESCOMP : std_logic_vector(Input_SZ-1 downto 0);
begin
RES <= REG;
OPinteger <= to_integer(signed(OP));
RESCOMP <= std_logic_vector(to_signed(-OPinteger,Input_SZ));
process(clk,reset)
begin
if(reset='0')then
REG <= (others => '0');
elsif(clk'event and clk='1')then
if(clr='1')then
REG <= (others => '0');
elsif(TwoComp='1')then
REG <= RESCOMP;
else
REG <= OP;
end if;
end if;
end process;
end ar_TwoComplementer;