Subversion Repositories mod_sim_exp

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----  dpram_generic                                               ---- 

----                                                              ---- 

----  This file is part of the                                    ----

----    Modular Simultaneous Exponentiation Core project          ---- 

----    http://www.opencores.org/cores/mod_sim_exp/               ---- 

----                                                              ---- 

----  Description                                                 ---- 

----    behavorial description of a dual port ram with one 32-bit ----

----    write port and one 32-bit read port                       ----            

----                                                              ---- 

----  Dependencies: none                                          ----

----                                                              ----

----  Authors:                                                    ----

----      - Geoffrey Ottoy, DraMCo research group                 ----

----      - Jonas De Craene, JonasDC@opencores.org                ---- 

----                                                              ---- 

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----                                                              ---- 

---- Copyright (C) 2011 DraMCo research group and OPENCORES.ORG   ---- 

----                                                              ---- 

---- This source file may be used and distributed without         ---- 

---- restriction provided that this copyright statement is not    ---- 

---- removed from the file and that any derivative work contains  ---- 

---- the original copyright notice and the associated disclaimer. ---- 

----                                                              ---- 

---- This source file is free software; you can redistribute it   ---- 

---- and/or modify it under the terms of the GNU Lesser General   ---- 

---- Public License as published by the Free Software Foundation; ---- 

---- either version 2.1 of the License, or (at your option) any   ---- 

---- later version.                                               ---- 

----                                                              ---- 

---- This source 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 Lesser General Public License for more ---- 

---- details.                                                     ---- 

----                                                              ---- 

---- You should have received a copy of the GNU Lesser General    ---- 

---- Public License along with this source; if not, download it   ---- 

---- from http://www.opencores.org/lgpl.shtml                     ---- 

----                                                              ---- 

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library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_unsigned.all;

library mod_sim_exp;

use mod_sim_exp.std_functions.all;

-- altera infers ramblocks from a depth of 9

-- xilinx infers ramblocks from a depth of 2

entity dpram_generic is

  generic (

    depth : integer := 2

  );

  port  (

    -- write port A

    clkA   : in std_logic;

    waddrA : in std_logic_vector(log2(depth)-1 downto 0);

    weA    : in std_logic;

    dinA   : in std_logic_vector(31 downto 0);

    -- read port B

    clkB   : in std_logic;

    raddrB : in std_logic_vector(log2(depth)-1 downto 0);

    doutB  : out std_logic_vector(31 downto 0)

  );

end dpram_generic;

architecture behavorial of dpram_generic is

  -- the memory

  type ram_type is array (depth-1 downto 0) of std_logic_vector (31 downto 0);

  shared variable RAM : ram_type := (others => (others => '0'));

  -- xilinx constraint to use blockram resources

  attribute ram_style : string;

  attribute ram_style of ram:variable is "block";

  -- altera constraints:

  -- for smal depths:

  --  if the synthesis option "allow any size of RAM to be inferred" is on, these lines 

  --  may be left commented.

  --  uncomment this attribute if that option is off and you know wich primitives should be used.

  --attribute ramstyle : string;

  --attribute ramstyle of RAM : variable is "M9K, no_rw_check";

begin

  process (clkA)

  begin

    if rising_edge(clkA) then

      if (weA = '1') then

        RAM(conv_integer(waddrA)) := dinA;

      end if;

    end if;

  end process;

  process (clkB)

  begin

    if rising_edge(clkB) then

      doutB <= RAM(conv_integer(raddrB));

    end if;

  end process;

end behavorial;