Subversion Repositories mod_sim_exp

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----  tdpram_asym                                                 ---- 

----                                                              ---- 

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

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

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

----                                                              ---- 

----  Description                                                 ---- 

----    behavorial description of an asymmetric true dual port    ----

----    ram with one (widthA)-bit read/write port and one 32-bit  ----

----    read/write port. Made using the templates of xilinx and   ----

----    altera for asymmetric ram.                                ----

----                                                              ---- 

----  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;

use ieee.std_logic_arith.all;

library mod_sim_exp;

use mod_sim_exp.std_functions.all;

-- altera infers ramblocks from a depth of 9 (or 2 with any ram size recognition 

-- option on or contstraint below on) and widthA 1,2,4,8,16

-- xilinx infers ramblocks from a depth of 2 and widthA 1,2,4,8,16,32

entity tdpram_asym is

  generic (

    depthB : integer := 4; -- nr of 32-bit words

    widthA : integer := 2;  -- port A width, must be smaller than or equal to 32

    device : string  := "xilinx"

  );

  port  (

    -- port A (widthA)-bit

    clkA  : in std_logic;

    addrA : in std_logic_vector(log2((depthB*32)/widthA)-1 downto 0);

    weA   : in std_logic;

    dinA  : in std_logic_vector(widthA-1 downto 0);

    doutA : out std_logic_vector(widthA-1 downto 0);

    -- port B 32-bit

    clkB  : in std_logic;

    addrB : in std_logic_vector(log2(depthB)-1 downto 0);

    weB   : in std_logic;

    dinB  : in std_logic_vector(31 downto 0);

    doutB : out std_logic_vector(31 downto 0)

  );

end tdpram_asym;

architecture behavorial of tdpram_asym is

  -- constants

  constant R : natural := 32/widthA; -- ratio

begin

  xilinx_device : if device="xilinx" generate

    -- An asymmetric RAM is modelled in a similar way as a symmetric RAM, with an

    -- array of array object. Its aspect ratio corresponds to the port with the

    -- lower data width (larger depth)

    type ramType is array (0 to ((depthB*32)/widthA)-1) of std_logic_vector(widthA-1 downto 0);

    -- You need to declare ram as a shared variable when :

    --   - the RAM has two write ports,

    --   - the RAM has only one write port whose data width is maxWIDTH

    -- In all other cases, ram can be a signal.

    shared variable ram : ramType := (others => (others => '0'));

  begin

    process (clkA)

    begin

      if rising_edge(clkA) then

        if weA = '1' then

          ram(conv_integer(addrA)) := dinA;

        end if;

        doutA <= ram(conv_integer(addrA));

      end if;

    end process;

    process (clkB)

    begin

      if rising_edge(clkB) then

        for i in 0 to R-1 loop

          if weB = '1' then

            ram(conv_integer(addrB & conv_std_logic_vector(i,log2(R))))

              := dinB((i+1)*widthA-1 downto i*widthA);

          end if;

          doutB((i+1)*widthA-1 downto i*widthA)

            <= ram(conv_integer(addrB & conv_std_logic_vector(i,log2(R))));

        end loop;

      end if;

    end process;

  end generate;

  altera_device : if device="altera" generate

    -- Use a multidimensional array to model mixed-width 

    type word_t is array(R-1 downto 0) of std_logic_vector(widthA-1 downto 0);

    type ram_t is array (0 to depthB-1) of word_t;

    -- 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 : signal is "M9K, no_rw_check";

    -- delcare the RAM

    signal ram : ram_t;

    signal wB_local : word_t;

    signal qB_local : word_t;

  begin  -- rtl

    -- Re-organize the write data to match the RAM word type

    unpack: for i in 0 to R-1 generate

      wB_local(i) <= dinB(widthA*(i+1)-1 downto widthA*i);

      doutB(widthA*(i+1)-1 downto widthA*i) <= qB_local(i);

    end generate unpack;

    --port B

    process(clkB)

    begin

      if(rising_edge(clkB)) then

        if(weB = '1') then

          ram(conv_integer(addrB)) <= wB_local;

        end if;

        qB_local <= ram(conv_integer(addrB));

      end if;

    end process;

    -- port A

    process(clkA)

    begin

      if(rising_edge(clkA)) then

        doutA <= ram(conv_integer(addrA) / R )(conv_integer(addrA) mod R);

        if(weA ='1') then

          ram(conv_integer(addrA) / R)(conv_integer(addrA) mod R) <= dinA;

        end if;

      end if;

    end process;

  end generate;

end behavorial;