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--

--      Input file         : config_Pkg.vhd

--      Design name        : config_Pkg

--      Author             : Tamar Kranenburg

--      Company            : Delft University of Technology

--                         : Faculty EEMCS, Department ME&CE

--                         : Systems and Circuits group

--

--      Description        : Testbench instantiates core, data memory and instruction memory,

--                           together with a character device.

--

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LIBRARY ieee;

USE ieee.std_logic_1164.ALL;

USE ieee.std_logic_unsigned.ALL;

LIBRARY std;

USE std.textio.ALL;

LIBRARY mblite;

USE mblite.config_Pkg.ALL;

USE mblite.core_Pkg.ALL;

USE mblite.std_Pkg.ALL;

ENTITY testbench IS

END testbench;

ARCHITECTURE arch OF testbench IS

    SIGNAL dmem_o : dmem_out_type;

    SIGNAL imem_o : imem_out_type;

    SIGNAL dmem_i : dmem_in_type;

    SIGNAL imem_i : imem_in_type;

    SIGNAL sys_clk_i : std_ulogic := '0';

    SIGNAL sys_int_i : std_ulogic := '0';

    SIGNAL sys_rst_i : std_ulogic := '0';

    SIGNAL sys_ena_i : std_ulogic := '1';

    CONSTANT std_out_adr : std_ulogic_vector(CFG_DMEM_SIZE - 1 DOWNTO 0) := X"FFFFFFC0";

    CONSTANT rom_size : integer := 16;

    CONSTANT ram_size : integer := 16;

    SIGNAL mem_enable : std_ulogic;

    SIGNAL chr_enable : std_ulogic;

    SIGNAL chr_read : std_ulogic;

    SIGNAL sel_o : std_ulogic_vector(3 DOWNTO 0);

    SIGNAL mem_dat : std_ulogic_vector(31 DOWNTO 0);

    SIGNAL chr_dat : std_ulogic_vector(31 DOWNTO 0);

    SIGNAL chr_cnt : integer := 0;

BEGIN

    sys_clk_i <= NOT sys_clk_i AFTER 10000 ps;

    sys_rst_i <= '1' AFTER 0 ps, '0' AFTER  150000 ps;

    sys_int_i <= '1' AFTER 500000000 ps, '0' after 500040000 ps;

    dmem_i.ena_i <= sys_ena_i;

    sel_o <= dmem_o.sel_o WHEN dmem_o.we_o = '1' ELSE (OTHERS => '0');

    mem_enable <= NOT sys_rst_i AND dmem_o.ena_o AND NOT compare(dmem_o.adr_o, std_out_adr);

    chr_enable <= NOT sys_rst_i AND dmem_o.ena_o AND compare(dmem_o.adr_o, std_out_adr);

    dmem_i.dat_i <= chr_dat WHEN chr_read = '1' ELSE mem_dat;

    -- Character device

    stdio: PROCESS(sys_clk_i)

        VARIABLE s    : line;

        VARIABLE byte : std_ulogic_vector(7 DOWNTO 0);

        VARIABLE char : character;

    BEGIN

        IF rising_edge(sys_clk_i) THEN

            IF chr_enable = '1' THEN

                IF dmem_o.we_o = '1' THEN

                -- WRITE STDOUT

                    CASE dmem_o.sel_o IS

                        WHEN "0001" => byte := dmem_o.dat_o( 7 DOWNTO  0);

                        WHEN "0010" => byte := dmem_o.dat_o(15 DOWNTO  8);

                        WHEN "0100" => byte := dmem_o.dat_o(23 DOWNTO 16);

                        WHEN "1000" => byte := dmem_o.dat_o(31 DOWNTO 24);

                        WHEN OTHERS => NULL;

                    END CASE;

                    char := character'val(my_conv_integer(byte));

                    IF byte = X"0D" THEN

                        -- Ignore character 13

                    ELSIF byte = X"0A" THEN

                        -- Writeline on character 10 (newline)

                        writeline(output, s);

                    ELSE

                        -- Write to buffer

                        write(s, char);

                    END IF;

                    chr_read <= '0';

                ELSE

                    chr_read <= '1';

                    IF chr_cnt = 0 THEN

                        chr_cnt <= 1;

                        chr_dat <= X"4C4C4C4C";

                    ELSIF chr_cnt = 1 THEN

                        chr_cnt <= 2;

                        chr_dat <= X"4D4D4D4D";

                    ELSIF chr_cnt = 2 THEN

                        chr_cnt <= 3;

                        chr_dat <= X"4E4E4E4E";

                    ELSIF chr_cnt = 3 THEN

                        chr_cnt <= 0;

                        chr_dat <= X"0A0A0A0A";

                    END IF;

                END IF;

            ELSE

                chr_read <= '0';

            END IF;

        END IF;

    END PROCESS;

    -- Warning: an infinite loop like while(1) {} triggers this timeout too!

    -- disable this feature when a premature finish occur.

    timeout: PROCESS(sys_clk_i)

    BEGIN

        IF NOW = 10 ms THEN

            REPORT "TIMEOUT" SEVERITY FAILURE;

        END IF;

        -- BREAK ON EXIT (0xB8000000)

        IF compare(imem_i.dat_i, "10111000000000000000000000000000") = '1' THEN

            -- Make sure the simulator finishes when an error is encountered.

            -- For modelsim: see menu Simulate -> Runtime options -> Assertions

            REPORT "FINISHED" SEVERITY FAILURE;

        END IF;

    END PROCESS;

    imem : sram GENERIC MAP

    (

        WIDTH => CFG_IMEM_WIDTH,

        SIZE => rom_size - 2

    )

    PORT MAP

    (

        dat_o => imem_i.dat_i,

        dat_i => "00000000000000000000000000000000",

        adr_i => imem_o.adr_o(rom_size - 1 DOWNTO 2),

        wre_i => '0',

        ena_i => imem_o.ena_o,

        clk_i => sys_clk_i

    );

    dmem : sram_4en GENERIC MAP

    (

        WIDTH => CFG_DMEM_WIDTH,

        SIZE => ram_size - 2

    )

    PORT MAP

    (

        dat_o => mem_dat,

        dat_i => dmem_o.dat_o,

        adr_i => dmem_o.adr_o(ram_size - 1 DOWNTO 2),

        wre_i => sel_o,

        ena_i => mem_enable,

        clk_i => sys_clk_i

    );

    core0 : core PORT MAP

    (

        imem_o => imem_o,

        dmem_o => dmem_o,

        imem_i => imem_i,

        dmem_i => dmem_i,

        int_i  => sys_int_i,

        rst_i  => sys_rst_i,

        clk_i  => sys_clk_i

    );

END arch;

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-- USE CONFIGURATIONS INSTEAD OF GENERICS TO IMPLEMENT - FOR EXAMPLE - DIFFERENT MEMORIES.

-- CONFIGURATIONS CAN HIERARCHICALLY INVOKE OTHER CONFIGURATIONS TO REDUCE THE SIZE OF THE

-- CONFIGURATION DECLARATION

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CONFIGURATION tb_conf_example OF testbench IS

    FOR arch

        FOR ALL: sram_4en

            USE ENTITY mblite.sram_4en(arch);

        END FOR;

    END FOR;

END tb_conf_example;