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gajos |
-----------------------------------------------------------------------
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---- ----
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---- Montgomery modular multiplier and exponentiator ----
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---- ----
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---- This file is part of the Montgomery modular multiplier ----
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---- and exponentiator project ----
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---- http://opencores.org/project,mod_mult_exp ----
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---- ----
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---- Description: ----
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---- This is state machine for the modular multiplier it consists----
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---- of three states, NOP the preparation stage, CALCULATE_START ----
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---- for the modular multiply and STOP for the presentation ----
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---- result. ----
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---- ----
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---- To Do: ----
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---- ----
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---- Author(s): ----
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---- - Krzysztof Gajewski, gajos@opencores.org ----
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---- k.gajewski@gmail.com ----
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---- ----
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-----------------------------------------------------------------------
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---- ----
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---- Copyright (C) 2014 Authors and OPENCORES.ORG ----
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---- ----
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---- This source file may be used and distributed without ----
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---- restriction provided that this copyright statement is not ----
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---- removed from the file and that any derivative work contains ----
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---- the original copyright notice and the associated disclaimer. ----
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---- ----
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---- This source file is free software; you can redistribute it ----
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---- and-or modify it under the terms of the GNU Lesser General ----
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---- Public License as published by the Free Software Foundation; ----
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---- either version 2.1 of the License, or (at your option) any ----
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---- later version. ----
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---- ----
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---- This source is distributed in the hope that it will be ----
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---- useful, but WITHOUT ANY WARRANTY; without even the implied ----
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---- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ----
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---- PURPOSE. See the GNU Lesser General Public License for more ----
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---- details. ----
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---- ----
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---- You should have received a copy of the GNU Lesser General ----
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---- Public License along with this source; if not, download it ----
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---- from http://www.opencores.org/lgpl.shtml ----
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---- ----
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-----------------------------------------------------------------------
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library IEEE;
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use IEEE.STD_LOGIC_1164.ALL;
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use IEEE.STD_LOGIC_UNSIGNED.ALL;
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use work.properties.ALL;
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-- Uncomment the following library declaration if using
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-- arithmetic functions with Signed or Unsigned values
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--use IEEE.NUMERIC_STD.ALL;
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-- Uncomment the following library declaration if instantiating
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-- any Xilinx primitives in this code.
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--library UNISIM;
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--use UNISIM.VComponents.all;
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entity ModMultIter_SM is
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generic (
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word_size : integer := WORD_LENGTH;
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word_binary : integer := WORD_INTEGER
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);
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port(
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x : in STD_LOGIC_VECTOR(word_size - 1 downto 0);
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start : in STD_LOGIC;
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clk : in STD_LOGIC;
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s_0 : in STD_LOGIC;
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y_0 : in STD_LOGIC;
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ready : out STD_LOGIC;
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out_reg_en : out STD_LOGIC;
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mux_mult_ctrl : out STD_LOGIC;
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mux_4in_ctrl : out STD_LOGIC_VECTOR(1 downto 0)
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);
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end ModMultIter_SM;
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architecture Behavioral of ModMultIter_SM is
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signal state : multiplier_states := NOP;
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signal next_state : multiplier_states := NOP;
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signal position_counter : STD_LOGIC_VECTOR(word_binary downto 0) := (others => '0');
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signal shift_reg : STD_LOGIC_VECTOR(word_size - 1 downto 0) := (others => '0');
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signal q : STD_LOGIC;
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begin
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q <= (shift_reg(0) and y_0) xor s_0;
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mux_4in_ctrl <= shift_reg(0) & q;
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SM : process(state, start, position_counter)
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begin
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case state is
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-- Prepare for the Montgomery iterations
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when NOP =>
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ready <= '0';
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if (start = '1') then
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next_state <= CALCULATE_START;
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out_reg_en <= '1';
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mux_mult_ctrl <= '1';
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else
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out_reg_en <= '0';
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mux_mult_ctrl <= '0';
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next_state <= NOP;
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end if;
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-- State for the calculations of the Montgomery iterations
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when CALCULATE_START =>
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mux_mult_ctrl <= '1';
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ready <= '0';
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-- End of iterations (counter contains the 'word_size' number)
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if (position_counter = (word_size - 1)) then
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out_reg_en <= '0';
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next_state <= STOP;
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-- Calculation process
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else
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out_reg_en <= '1';
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next_state <= CALCULATE_START;
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end if;
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-- End of the calculations
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when STOP =>
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ready <= '1';
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mux_mult_ctrl <= '1';
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out_reg_en <= '0';
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if (start = '1') then
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next_state <= STOP;
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else
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next_state <= NOP;
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end if;
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end case;
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end process SM;
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-- Shift register enabling proper calculations of the all Montgomery iterations
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shift : process (clk, state)
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begin
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if (clk = '0' and clk'Event) then
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if (state = CALCULATE_START) then
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shift_reg <= shift_reg(0) & shift_reg(word_size - 1 downto 1);
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else
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shift_reg <= x;
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end if;
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end if;
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end process shift;
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-- Process for the state change between each clock tick
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state_control : process (clk, start)
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begin
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if (start = '0') then
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state <= NOP;
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elsif (clk = '1' and clk'Event) then
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state <= next_state;
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end if;
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end process state_control;
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-- Counter for controlling the number of the montgomery iterations during counting
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couner_modifier : process (clk)
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begin
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if (clk = '1' and clk'Event) then
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if (state = CALCULATE_START) then
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position_counter <= position_counter + 1;
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else
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position_counter <= (others => '0');
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end if;
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end if;
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end process couner_modifier;
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end Behavioral;
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