Subversion Repositories srl_fifo

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---- This file is part of the srl_fifo project                                              ----

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

----                                                                                                                ----

---- Description                                                                                                ----

---- Implementation of srl_fifo IP core according to                    ----

---- srl_fifo IP core specification document.                                   ----

----                                                                                                                ----

---- To Do:                                                                                                         ----

----    NA                                                                                                          ----

----                                                                                                                ----

---- Author(s):                                                                                             ----

----   Andrew Mulcock, amulcock@opencores.org                                   ----

----                                                                                                                ----

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---- Copyright (C) 2008 Authors 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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--                                                                                                                      ----

-- CVS Revision History                                                                                 ----

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-- $Log: not supported by cvs2svn $                                                                                                         ----

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--

-- quick description

--

--  Based upon the using a shift register as a fifo which has been 

--   around for years ( decades ), but really came of use to VHDL 

--   when the Xilinx FPGA's started having SRL's. 

--

--  In my view, the definitive article on shift register logic fifo's 

--   comes from Mr Chapman at Xilinx, in the form of his BBFIFO

--    tecXeclusive article, which as at early 2008, Xilinx have

--     removed.

--

LIBRARY ieee;

USE ieee.std_logic_1164.ALL;

USE ieee.std_logic_unsigned.all;

USE ieee.numeric_std.ALL;

ENTITY tb_srl_fifo_16_vhd IS

END tb_srl_fifo_16_vhd;

ARCHITECTURE behavior OF tb_srl_fifo_16_vhd IS

constant width_tb : integer := 8;

        -- Component Declaration for the Unit Under Test (UUT)

        COMPONENT srl_fifo_16

    GENERIC ( width : integer := width_tb ); -- set to how wide fifo is to be

        PORT(

                data_in : IN std_logic_vector(width_tb - 1 downto 0);

                reset : IN std_logic;

                write : IN std_logic;

                read : IN std_logic;

                clk : IN std_logic;

                data_out : OUT std_logic_vector(width_tb - 1  downto 0);

                full : OUT std_logic;

                half_full : OUT std_logic;

                data_present : OUT std_logic

                );

        END COMPONENT;

        --Inputs

        SIGNAL reset :  std_logic := '0';

        SIGNAL write :  std_logic := '0';

        SIGNAL read :  std_logic := '0';

        SIGNAL clk :  std_logic := '0';

        SIGNAL data_in :  std_logic_vector(width_tb - 1 downto 0) := (others=>'0');

        --Outputs

        SIGNAL data_out :  std_logic_vector(width_tb -1  downto 0);

        SIGNAL full :  std_logic;

        SIGNAL half_full :  std_logic;

        SIGNAL data_present :  std_logic;

BEGIN

        -- Instantiate the Unit Under Test (UUT)

        uut: srl_fifo_16

        GENERIC MAP (

        width => width_tb

        )

        PORT MAP(

                data_in => data_in,

                data_out => data_out,

                reset => reset,

                write => write,

                read => read,

                full => full,

                half_full => half_full,

                data_present => data_present,

                clk => clk

        );

        tb : PROCESS

        BEGIN

        reset <= '1';

                -- Wait 100 ns for global reset to finish

                wait for 100 ns;

        wait until clk = '0';

        reset <= '0';

                -- Place stimulus here

    wait until clk = '0';  -- 0

    data_in <= X"AA";

    write <= '1';

    wait until clk = '0';   -- 1

    data_in <= X"55";

    wait until clk = '0';   -- 2

    data_in <= X"02";

    wait until clk = '0';   -- 3

    data_in <= X"03";

    wait until clk = '0';   -- 4

    data_in <= X"04";

    wait until clk = '0';   -- 5

    data_in <= X"05";

    wait until clk = '0';   -- 6

    data_in <= X"06";

    wait until clk = '0';   -- 7

    data_in <= X"07";

    wait until clk = '0';   -- 8

    data_in <= X"08";

    wait until clk = '0';   -- 9

    data_in <= X"09";

    wait until clk = '0';   -- A

    data_in <= X"A0";

    wait until clk = '0';   -- B

    data_in <= X"B0";

    wait until clk = '0';   -- C

    data_in <= X"C0";

    wait until clk = '0';   -- D

    data_in <= X"D0";

    wait until clk = '0';   -- E

    data_in <= X"E0";

    wait until clk = '0';   -- F

    data_in <= X"F0";

    wait until clk = '0';   -- no write

    data_in <= X"FF";

    wait until clk = '0';   -- write and read on full, reads first out

    data_in <= X"EE";

    read <= '1';

    wait until clk = '0';   -- no read or write

    data_in <= X"AB";

    read <= '0';

    write <= '0';

-- read untill empty

    wait until clk = '0';

    read <= '1';

    for i in 0 to 13 loop   -- read out 13 more

        wait until clk = '0';

    end loop;

    read <= '0';

    wait until clk = '0';   --  dont read, 

    read <= '1';

    wait until clk = '0';   -- read last - 1 out

    read <= '0';

    wait until clk = '0';   --  dont read, 

    read <= '1';

    wait until clk = '0';   -- read last out

    read <= '0';    -- stop reading

                wait; -- will wait forever

        END PROCESS;

-- clock gen process

process

begin

    wait for 1 ns;

    clk <= '0';

    wait for 1 ns;

    clk <= '1';

end process;

END;