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[/] [mod_sim_exp/] [trunk/] [rtl/] [vhdl/] [ram/] [dpram_asym.vhd] - Blame information for rev 66

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1 66 JonasDC
----------------------------------------------------------------------  
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----  dpram_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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----    behavorial description of an asymmetric dual port ram     ----
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----    with one (wrwidth)-bit write port and one 32-bit read     ----
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----    port. Made using the templates of xilinx and altera for   ----
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----    asymmetric ram.                                           ----            
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----                                                              ---- 
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----  Dependencies: none                                          ----
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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_unsigned.all;
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use ieee.std_logic_arith.all;
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library mod_sim_exp;
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use mod_sim_exp.std_functions.all;
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-- altera infers ramblocks from a depth of 9 (or 2 with any ram size recognition 
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-- option on or contstraint below on) and wrwidth 1,2,4,8,16
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-- xilinx infers ramblocks from a depth of 2 and wrwidth 1,2,4,8,16,32
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entity dpram_asym is
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  generic (
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    rddepth : integer := 4; -- nr of 32-bit words
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    wrwidth : integer := 2; -- write width, must be smaller than or equal to 32
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    device  : string  := "xilinx"  -- device template to use
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  );
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  port  (
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    clk : in std_logic;
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    -- write port
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    waddr : in std_logic_vector(log2((rddepth*32)/wrwidth)-1 downto 0);
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    we    : in std_logic;
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    din   : in std_logic_vector(wrwidth-1 downto 0);
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    -- read port
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    raddr : in std_logic_vector(log2(rddepth)-1 downto 0);
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    dout  : out std_logic_vector(31 downto 0)
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  );
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end dpram_asym;
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architecture behavorial of dpram_asym is
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  -- constants
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  constant R       : natural := 32/wrwidth; -- ratio
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  constant wrdepth : integer := (rddepth*32)/wrwidth;
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begin
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  xilinx_device : if device="xilinx" generate
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    -- the memory
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    type ram_type is array (wrdepth-1 downto 0) of std_logic_vector (wrwidth-1 downto 0);
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    signal RAM : ram_type := (others => (others => '0'));
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    -- xilinx constraint to use blockram resources
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    attribute ram_style : string;
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    attribute ram_style of ram:signal is "block";
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  begin
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    process (clk)
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    begin
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      if (clk'event and clk = '1') then
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        if (we = '1') then
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          RAM(conv_integer(waddr)) <= din;
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        end if;
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        for i in 0 to R-1 loop
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          dout((i+1)*wrwidth-1 downto i*wrwidth)
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                <= RAM(conv_integer(raddr & conv_std_logic_vector(i,log2(R))));
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        end loop;
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      end if;
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    end process;
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  end generate;
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  altera_device : if device="altera" generate
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    -- Use a multidimensional array to model mixed-width 
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    type word_t is array(R-1 downto 0) of std_logic_vector(wrwidth-1 downto 0);
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    type ram_t is array (0 to rddepth-1) of word_t;
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    signal ram : ram_t;
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    signal q_local : word_t;
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    -- altera constraints:
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    -- for smal depths:
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    --  if the synthesis option "allow any size of RAM to be inferred" is on, these lines 
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    --  may be left commented.
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    --  uncomment this attribute if that option is off and you know wich primitives should be used.
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    --attribute ramstyle : string;
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    --attribute ramstyle of RAM : signal is "M9K, no_rw_check";
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  begin
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    unpack: for i in 0 to R - 1 generate
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      dout(wrwidth*(i+1) - 1 downto wrwidth*i) <= q_local(i);
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    end generate unpack;
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    process(clk, we)
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    begin
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      if(rising_edge(clk)) then
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        if(we = '1') then
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          ram(conv_integer(waddr)/R)(conv_integer(waddr) mod R) <= din;
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        end if;
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        q_local <= ram(conv_integer(raddr));
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      end if;
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    end process;
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  end generate;
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end behavorial;

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