Subversion Repositories mod_sim_exp

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----  fifo_primitive                                              ---- 

----                                                              ---- 

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

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

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

----                                                              ---- 

----  Description                                                 ---- 

----    512 x 32 bit fifo                                         ----

----                                                              ---- 

----  Dependencies:                                               ----

----    - FIFO18E1 (xilinx primitive)                             ----

----                                                              ----

----  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_arith.all;

use ieee.std_logic_unsigned.all;

-- Xilinx primitives used in this code.

library UNISIM;

use UNISIM.VComponents.all;

entity fifo_primitive is

  port (

    push_clk : in  std_logic;

    pop_clk  : in  std_logic;

    din      : in  std_logic_vector (31 downto 0);

    dout     : out  std_logic_vector (31 downto 0);

    empty    : out  std_logic;

    full     : out  std_logic;

    push     : in  std_logic;

    pop      : in  std_logic;

    reset    : in std_logic;

    nopop    : out std_logic;

    nopush   : out std_logic

  );

end fifo_primitive;

architecture Behavioral of fifo_primitive is

        signal rdcount : std_logic_vector(11 downto 0); -- debugging

        signal wrcount : std_logic_vector(11 downto 0); -- debugging

        signal reset_i, pop_i, push_i, empty_i, full_i, wrerr_i, rderr_i : std_logic;

begin

        empty <= empty_i;

        full <= full_i;

        -- these logical equations need to be extended where necessary

        nopop <= rderr_i or (pop and reset_i);

        nopush <= wrerr_i or (push and reset_i);

        pop_i <= pop and (not reset_i);

        push_i <= push and (not reset_i);

        -- makes the reset at least three clk_cycles long

        RESET_PROC: process (reset, push_clk)

                variable clk_counter : integer range 0 to 3 := 3;

        begin

                if reset = '1' then

                        reset_i <= '1';

                        clk_counter := 3;

                elsif rising_edge(push_clk) then

                        if clk_counter = 0 then

                                clk_counter := 0;

                                reset_i <= '0';

                        else

                                clk_counter := clk_counter - 1;

                                reset_i <= '1';

                        end if;

                end if;

        end process;

   FIFO18E1_inst : FIFO18E1

   generic map (

      ALMOST_EMPTY_OFFSET => X"00080",  -- Sets the almost empty threshold

      ALMOST_FULL_OFFSET => X"00080",   -- Sets almost full threshold

      DATA_WIDTH => 36,                 -- Sets data width to 4, 9, 18, or 36

      DO_REG => 1,                      -- Enable output register (0 or 1) Must be 1 if EN_SYN = "FALSE" 

      EN_SYN => FALSE,                   -- Specifies FIFO as dual-clock ("FALSE") or Synchronous ("TRUE")

      FIFO_MODE => "FIFO18_36",         -- Sets mode to FIFO18 or FIFO18_36

      FIRST_WORD_FALL_THROUGH => FALSE, -- Sets the FIFO FWFT to "TRUE" or "FALSE" 

      INIT => X"000000000",             -- Initial values on output port

      SRVAL => X"000000000"             -- Set/Reset value for output port

   )

   port map (

     -- ALMOSTEMPTY => ALMOSTEMPTY, -- 1-bit almost empty output flag

     -- ALMOSTFULL => ALMOSTFULL,   -- 1-bit almost full output flag

      DO => dout,                   -- 32-bit data output

     -- DOP => DOP,                 -- 4-bit parity data output

      EMPTY => empty_i,             -- 1-bit empty output flag

      FULL => full_i,               -- 1-bit full output flag

      -- WRCOUNT, RDCOUNT: 12-bit (each) FIFO pointers

      RDCOUNT => RDCOUNT,           -- 12-bit read count output

      WRCOUNT => WRCOUNT,           -- 12-bit write count output

      -- WRERR, RDERR: 1-bit (each) FIFO full or empty error

      RDERR => rderr_i,             -- 1-bit read error output

      WRERR => wrerr_i,             -- 1-bit write error

      DI => din,                    -- 32-bit data input

      DIP => "0000",                -- 4-bit parity input

      RDEN => pop_i,                -- 1-bit read enable input

      REGCE => '1',                 -- 1-bit clock enable input

      RST => reset_i,               -- 1-bit reset input

      RSTREG => reset_i,            -- 1-bit output register set/reset

      -- WRCLK, RDCLK: 1-bit (each) Clocks

      RDCLK => pop_clk,                 -- 1-bit read clock input

      WRCLK => push_clk,                 -- 1-bit write clock input

      WREN => push_i                -- 1-bit write enable input

   );

end Behavioral;