tb_full_adder.vhw

Self timed pipelined adder

--------------------------------------------------------------------------------
-- Copyright (c) 1995-2003 Xilinx, Inc.
-- All Right Reserved.
--------------------------------------------------------------------------------
--   ____  ____ 
--  /   /\/   / 
-- /___/  \  /    Vendor: Xilinx 
-- \   \   \/     Version : 8.1i
--  \   \         Application : ISE
--  /   /         Filename : TB_Full_Adder.vhw
-- /___/   /\     Timestamp : Fri May 19 19:59:31 2006
-- \   \  /  \ 
--  \___\/\___\ 
--
--Command: 
--Design Name: TB_Full_Adder
--Device: Xilinx
--

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
USE IEEE.STD_LOGIC_TEXTIO.ALL;
USE STD.TEXTIO.ALL;

ENTITY TB_Full_Adder IS
END TB_Full_Adder;

ARCHITECTURE testbench_arch OF TB_Full_Adder IS
    FILE RESULTS: TEXT OPEN WRITE_MODE IS "results.txt";

    COMPONENT Full_Adder
        PORT (
            inA : In std_logic_vector (1 DownTo 0);
            inB : In std_logic_vector (1 DownTo 0);
            Start : In std_logic;
            Done : Out std_logic;
            Reset : In std_logic;
            Output : Out std_logic;
            CarryIn : In std_logic;
            CarryOut : Out std_logic
        );
    END COMPONENT;

    SIGNAL inA : std_logic_vector (1 DownTo 0) := "00";
    SIGNAL inB : std_logic_vector (1 DownTo 0) := "00";
    SIGNAL Start : std_logic := '0';
    SIGNAL Done : std_logic := 'U';
    SIGNAL Reset : std_logic := '1';
    SIGNAL Output : std_logic := 'U';
    SIGNAL CarryIn : std_logic := '0';
    SIGNAL CarryOut : std_logic := 'U';

    SHARED VARIABLE TX_ERROR : INTEGER := 0;
    SHARED VARIABLE TX_OUT : LINE;

    BEGIN
        UUT : Full_Adder
        PORT MAP (
            inA => inA,
            inB => inB,
            Start => Start,
            Done => Done,
            Reset => Reset,
            Output => Output,
            CarryIn => CarryIn,
            CarryOut => CarryOut
        );

        PROCESS
            PROCEDURE CHECK_CarryOut(
                next_CarryOut : std_logic;
                TX_TIME : INTEGER
            ) IS
                VARIABLE TX_STR : String(1 to 4096);
                VARIABLE TX_LOC : LINE;
                BEGIN
                IF (CarryOut /= next_CarryOut) THEN
                    STD.TEXTIO.write(TX_LOC, string'("Error at time="));
                    STD.TEXTIO.write(TX_LOC, TX_TIME);
                    STD.TEXTIO.write(TX_LOC, string'("ns CarryOut="));
                    IEEE.STD_LOGIC_TEXTIO.write(TX_LOC, CarryOut);
                    STD.TEXTIO.write(TX_LOC, string'(", Expected = "));
                    IEEE.STD_LOGIC_TEXTIO.write(TX_LOC, next_CarryOut);
                    STD.TEXTIO.write(TX_LOC, string'(" "));
                    TX_STR(TX_LOC.all'range) := TX_LOC.all;
                    STD.TEXTIO.writeline(RESULTS, TX_LOC);
                    STD.TEXTIO.Deallocate(TX_LOC);
                    ASSERT (FALSE) REPORT TX_STR SEVERITY ERROR;
                    TX_ERROR := TX_ERROR + 1;
                END IF;
            END;
            PROCEDURE CHECK_Done(
                next_Done : std_logic;
                TX_TIME : INTEGER
            ) IS
                VARIABLE TX_STR : String(1 to 4096);
                VARIABLE TX_LOC : LINE;
                BEGIN
                IF (Done /= next_Done) THEN
                    STD.TEXTIO.write(TX_LOC, string'("Error at time="));
                    STD.TEXTIO.write(TX_LOC, TX_TIME);
                    STD.TEXTIO.write(TX_LOC, string'("ns Done="));
                    IEEE.STD_LOGIC_TEXTIO.write(TX_LOC, Done);
                    STD.TEXTIO.write(TX_LOC, string'(", Expected = "));
                    IEEE.STD_LOGIC_TEXTIO.write(TX_LOC, next_Done);
                    STD.TEXTIO.write(TX_LOC, string'(" "));
                    TX_STR(TX_LOC.all'range) := TX_LOC.all;
                    STD.TEXTIO.writeline(RESULTS, TX_LOC);
                    STD.TEXTIO.Deallocate(TX_LOC);
                    ASSERT (FALSE) REPORT TX_STR SEVERITY ERROR;
                    TX_ERROR := TX_ERROR + 1;
                END IF;
            END;
            PROCEDURE CHECK_Output(
                next_Output : std_logic;
                TX_TIME : INTEGER
            ) IS
                VARIABLE TX_STR : String(1 to 4096);
                VARIABLE TX_LOC : LINE;
                BEGIN
                IF (Output /= next_Output) THEN
                    STD.TEXTIO.write(TX_LOC, string'("Error at time="));
                    STD.TEXTIO.write(TX_LOC, TX_TIME);
                    STD.TEXTIO.write(TX_LOC, string'("ns Output="));
                    IEEE.STD_LOGIC_TEXTIO.write(TX_LOC, Output);
                    STD.TEXTIO.write(TX_LOC, string'(", Expected = "));
                    IEEE.STD_LOGIC_TEXTIO.write(TX_LOC, next_Output);
                    STD.TEXTIO.write(TX_LOC, string'(" "));
                    TX_STR(TX_LOC.all'range) := TX_LOC.all;
                    STD.TEXTIO.writeline(RESULTS, TX_LOC);
                    STD.TEXTIO.Deallocate(TX_LOC);
                    ASSERT (FALSE) REPORT TX_STR SEVERITY ERROR;
                    TX_ERROR := TX_ERROR + 1;
                END IF;
            END;
            BEGIN
                -- -------------  Current Time:  50ns
                WAIT FOR 50 ns;
                CHECK_CarryOut('0', 50);
                CHECK_Done('0', 50);
                CHECK_Output('0', 50);
                -- -------------------------------------
                -- -------------  Current Time:  100ns
                WAIT FOR 50 ns;
                Reset <= '0';
                -- -------------------------------------
                -- -------------  Current Time:  200ns
                WAIT FOR 100 ns;
                Start <= '1';
                -- -------------------------------------
                -- -------------  Current Time:  250ns
                WAIT FOR 50 ns;
                CHECK_Done('1', 250);
                -- -------------------------------------
                -- -------------  Current Time:  300ns
                WAIT FOR 50 ns;
                Start <= '0';
                -- -------------------------------------
                -- -------------  Current Time:  400ns
                WAIT FOR 100 ns;
                CarryIn <= '1';
                -- -------------------------------------
                -- -------------  Current Time:  500ns
                WAIT FOR 100 ns;
                Start <= '0';
                inA <= "01";
                -- -------------------------------------
                -- -------------  Current Time:  600ns
                WAIT FOR 100 ns;
                Start <= '1';
                inB <= "00";
                -- -------------------------------------
                -- -------------  Current Time:  650ns
                WAIT FOR 50 ns;
                CHECK_CarryOut('1', 650);
                -- -------------------------------------
                -- -------------  Current Time:  700ns
                WAIT FOR 50 ns;
                Start <= '0';
                -- -------------------------------------
                -- -------------  Current Time:  800ns
                WAIT FOR 100 ns;
                inB <= "01";
                -- -------------------------------------
                -- -------------  Current Time:  900ns
                WAIT FOR 100 ns;
                Start <= '1';
                -- -------------------------------------
                -- -------------  Current Time:  950ns
                WAIT FOR 50 ns;
                CHECK_Output('1', 950);
                WAIT FOR 50 ns;

                IF (TX_ERROR = 0) THEN
                    STD.TEXTIO.write(TX_OUT, string'("No errors or warnings"));
                    STD.TEXTIO.writeline(RESULTS, TX_OUT);
                    ASSERT (FALSE) REPORT
                      "Simulation successful (not a failure).  No problems detected."
                      SEVERITY FAILURE;
                ELSE
                    STD.TEXTIO.write(TX_OUT, TX_ERROR);
                    STD.TEXTIO.write(TX_OUT,
                        string'(" errors found in simulation"));
                    STD.TEXTIO.writeline(RESULTS, TX_OUT);
                    ASSERT (FALSE) REPORT "Errors found during simulation"
                         SEVERITY FAILURE;
                END IF;
            END PROCESS;

    END testbench_arch;