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[/] [mod_sim_exp/] [trunk/] [rtl/] [vhdl/] [core/] [modulus_ram_asym.vhd] - Blame information for rev 67

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1 67 JonasDC 
----------------------------------------------------------------------
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----  modulus_ram_asym                                            ----
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----                                                              ----
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----  This file is part of the                                    ----
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----    Modular Simultaneous Exponentiation Core project          ----
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----    http://www.opencores.org/cores/mod_sim_exp/               ----
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----                                                              ----
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----  Description                                                 ----
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----    BRAM memory and logic to store the modulus, due to the    ----
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----    achitecture, a minimum depth of 2 is needed for this      ----
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----    module to be inferred into blockram, this version is      ----
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----    slightly more performant than modulus_ram_gen and uses    ----
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----    less resources. but does not work on every fpga, only     ----
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----    the ones that support asymmetric rams.                    ----
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----                                                              ----
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----  Dependencies:                                               ----
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----    - dpramblock_asym                                         ----
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----                                                              ----
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----  Authors:                                                    ----
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----      - Geoffrey Ottoy, DraMCo research group                 ----
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----      - Jonas De Craene, JonasDC@opencores.org                ----
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----                                                              ----
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----------------------------------------------------------------------
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----                                                              ----
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---- Copyright (C) 2011 DraMCo research group 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_arith.all;
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use ieee.std_logic_unsigned.all;
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library mod_sim_exp;
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use mod_sim_exp.std_functions.all;
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-- structural description of a RAM to hold the modulus, with
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-- adjustable width (64, 128, 256, 512, 576, 640,..) and depth(nr of moduluses)
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--    formula for available widths: (i*512+(0 or 64 or 128 or 256)) (i=integer number)
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--
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entity modulus_ram_asym is
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  generic(
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    width : integer := 1536;  -- must be a multiple of 32
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    depth : integer := 2;     -- nr of moduluses
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    device : string := "xilinx"
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  );
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  port(
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    clk            : in std_logic;
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      -- bus side
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    write_modulus  : in std_logic; -- write enable
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    modulus_in_sel : in std_logic_vector(log2(depth)-1 downto 0); -- modulus operand to write to
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    modulus_addr   : in std_logic_vector(log2((width)/32)-1 downto 0); -- modulus word(32-bit) address
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    modulus_in     : in std_logic_vector(31 downto 0); -- modulus word data in
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    modulus_sel    : in std_logic_vector(log2(depth)-1 downto 0); -- selects the modulus to use for multiplications
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      -- multiplier side
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    modulus_out    : out std_logic_vector(width-1 downto 0)
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  );
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end modulus_ram_asym;
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architecture structural of modulus_ram_asym is
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  -- constants
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  constant RAMblock_maxwidth   : integer := 512;
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  constant nrRAMblocks_full    : integer := width/RAMblock_maxwidth;
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  constant RAMblock_part       : integer := width rem RAMblock_maxwidth;
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  constant RAMblock_part_width : integer := width-(nrRAMblocks_full*RAMblock_maxwidth);
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  constant RAMselect_aw        : integer := log2(width/32)-log2(nrRAMblocks_full/32);
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begin
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  -- generate (width/512) ramblocks with a given depth
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  -- these rams are tyed together to form the following structure
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  --  dual port ram:
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  --  - PORT A : 32-bit write
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  --  - PORT B : (width)-bit read
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  --
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  single_block : if (width <= RAMblock_maxwidth) generate
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    signal waddr : std_logic_vector(log2((width*depth)/32)-1 downto 0);
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  begin
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    waddr <= modulus_in_sel & modulus_addr;
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    ramblock: entity mod_sim_exp.dpramblock_asym
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    generic map(
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      width => width,
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      depth => depth,
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      device  => device
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    )
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    port map(
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      clk => clk,
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      -- write port
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      waddr => waddr,
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      we    => write_modulus,
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      din   => modulus_in,
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      -- read port
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      raddr => modulus_sel,
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      dout  => modulus_out
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    );
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  end generate;
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  multiple_full_blocks : if (width > RAMblock_maxwidth) generate
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    -- signals for multiple blocks
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    signal waddr  : std_logic_vector(log2(RAMblock_maxwidth*depth/32)-1 downto 0);
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    signal we_RAM : std_logic_vector(nrRAMblocks_full-1 downto 0);
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  begin
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    ramblocks_full : for i in 0 to nrRAMblocks_full generate
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      -- write port signal
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      waddr <= modulus_in_sel & modulus_addr(log2(RAMblock_maxwidth/32)-1 downto 0);
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      full_ones : if (i < nrRAMblocks_full) generate
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        ramblock_full : entity mod_sim_exp.dpramblock_asym
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        generic map(
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          width  => RAMblock_maxwidth,
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          depth  => depth,
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          device => device
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        )
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        port map(
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          clk => clk,
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          -- write port
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          waddr => waddr,
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          we    => we_RAM(i),
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          din   => modulus_in,
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          -- read port
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          raddr => modulus_sel,
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          dout  => modulus_out((i+1)*RAMblock_maxwidth-1 downto i*RAMblock_maxwidth)
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        );
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        -- we
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        process (write_modulus, modulus_addr)
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        begin
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          if modulus_addr(log2(width/32)-1 downto log2(RAMblock_maxwidth/32)) = conv_std_logic_vector(i,RAMselect_aw) then
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            we_RAM(i) <= write_modulus;
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          else
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            we_RAM(i) <= '0';
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          end if;
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        end process;
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      end generate; -- end of if generate for full blocks
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      optional_part : if (i = nrRAMblocks_full) and (RAMblock_part /= 0) generate
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        -- signals for optional part
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        signal waddr_part : std_logic_vector(log2(RAMblock_part_width*depth/32)-1 downto 0);
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        signal we_part    : std_logic;
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      begin
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        -- write port signal
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        waddr_part <= modulus_in_sel & modulus_addr(log2(RAMblock_part_width/32)-1 downto 0);
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        ramblock_part : entity mod_sim_exp.dpramblock_asym
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        generic map(
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          width  => RAMblock_part_width,
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          depth  => depth,
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          device => device
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        )
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        port map(
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          clk => clk,
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          -- write port
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          waddr => waddr_part,
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          we    => we_part,
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          din   => modulus_in,
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          -- read port
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          raddr => modulus_sel,
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          dout  => modulus_out(width-1 downto i*RAMblock_maxwidth)
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        );
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        -- we_part
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        process (write_modulus, modulus_addr)
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        begin
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          if modulus_addr(log2(width/32)-1 downto log2(RAMblock_maxwidth/32)) = conv_std_logic_vector(i,RAMselect_aw) then
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            we_part <= write_modulus;
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          else
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            we_part <= '0';
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          end if;
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        end process;
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      end generate;-- end of if generate for part block
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    end generate;-- end of for generate
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  end generate;-- end of if generate for multiple blocks
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end structural;

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