Subversion Repositories astron_statistics

-------------------------------------------------------------------------------

--

-- Copyright 2020

-- ASTRON (Netherlands Institute for Radio Astronomy) <http://www.astron.nl/>

-- P.O.Box 2, 7990 AA Dwingeloo, The Netherlands

-- 

-- Licensed under the Apache License, Version 2.0 (the "License");

-- you may not use this file except in compliance with the License.

-- You may obtain a copy of the License at

-- 

--     http://www.apache.org/licenses/LICENSE-2.0

-- 

-- Unless required by applicable law or agreed to in writing, software

-- distributed under the License is distributed on an "AS IS" BASIS,

-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

-- See the License for the specific language governing permissions and

-- limitations under the License.

--

-------------------------------------------------------------------------------

LIBRARY IEEE, common_pkg_lib, common_components_lib;

USE IEEE.std_logic_1164.ALL;

USE IEEE.numeric_std.ALL;

USE common_pkg_lib.common_pkg.ALL;

ENTITY tb_st_acc IS

  GENERIC (

    g_dat_w            : NATURAL := 6;

    g_acc_w            : NATURAL := 9;

    g_hold_load        : BOOLEAN := TRUE;

    g_pipeline_input   : NATURAL := 0;

    g_pipeline_output  : NATURAL := 4

  );

END tb_st_acc;

ARCHITECTURE tb OF tb_st_acc IS

  CONSTANT clk_period    : TIME := 10 ns;

  CONSTANT c_pipeline    : NATURAL := g_pipeline_input + g_pipeline_output;

  FUNCTION func_acc(in_dat, in_acc  : STD_LOGIC_VECTOR;

                    in_val, in_load : STD_LOGIC) RETURN STD_LOGIC_VECTOR IS

    VARIABLE v_dat, v_acc, v_result : INTEGER;

  BEGIN

    -- Calculate expected result

    IF in_val='0' THEN              -- hold: out_acc = in_acc

      v_result := TO_SINT(in_acc);

    ELSIF in_load='1' THEN           -- force: out_acc = 0 + in_dat

      v_result := TO_SINT(in_dat);

    ELSE                            -- accumulate: out_acc = in_acc + in_dat

      v_result := TO_SINT(in_dat) + TO_SINT(in_acc);

    END IF;

    -- Wrap to avoid warning: NUMERIC_STD.TO_SIGNED: vector truncated

    IF v_result >  2**(g_acc_w-1)-1 THEN v_result := v_result - 2**g_acc_w; END IF;

    IF v_result < -2**(g_acc_w-1)   THEN v_result := v_result + 2**g_acc_w; END IF;

    RETURN TO_SVEC(v_result, g_acc_w);

  END;

  SIGNAL tb_end          : STD_LOGIC := '0';

  SIGNAL clk             : STD_LOGIC := '0';

  SIGNAL in_dat          : STD_LOGIC_VECTOR(g_dat_w-1 DOWNTO 0);

  SIGNAL in_acc          : STD_LOGIC_VECTOR(g_acc_w-1 DOWNTO 0) := (OTHERS=>'0');

  SIGNAL in_val          : STD_LOGIC;

  SIGNAL in_load         : STD_LOGIC;

  SIGNAL out_val         : STD_LOGIC;

  SIGNAL out_acc         : STD_LOGIC_VECTOR(g_acc_w-1 DOWNTO 0);

  SIGNAL expected_acc_p  : STD_LOGIC_VECTOR(g_acc_w-1 DOWNTO 0);

  SIGNAL expected_acc    : STD_LOGIC_VECTOR(g_acc_w-1 DOWNTO 0);

BEGIN

  clk  <= NOT clk OR tb_end AFTER clk_period/2;

  ------------------------------------------------------------------------------

  -- Input stimuli

  ------------------------------------------------------------------------------

  -- run -all

  p_stimuli : PROCESS

  BEGIN

    in_load <= '0';

    in_dat <= TO_SVEC(0, g_dat_w);

    in_val <= '0';

    WAIT UNTIL rising_edge(clk);

    FOR I IN 0 TO 9 LOOP WAIT UNTIL rising_edge(clk); END LOOP;

    in_load <= '1';

    in_val <= '1';

    FOR R IN 0 TO 2 LOOP  -- Repeat some intervals marked by in_load = '1'

      in_load <= '1';

      -- All combinations

      FOR I IN -2**(g_dat_w-1) TO 2**(g_dat_w-1)-1 LOOP

        in_dat <= TO_SVEC(I, g_dat_w);

        WAIT UNTIL rising_edge(clk);

        -- keep in_load low during rest of period

        in_load <= '0';

--         -- keep in_val low during rest of st_acc latency, to ease manual interpretation of out_acc as in_acc

--         in_val <= '0';

--         FOR J IN 1 TO c_pipeline-1 LOOP WAIT UNTIL rising_edge(clk); END LOOP;

--         in_val <= '1';

      END LOOP;

    END LOOP;

    in_load <= '1';  -- keep '1' to avoid further toggling of out_acc (in a real design this would safe power)

    in_val <= '0';

    FOR I IN 0 TO 9 LOOP WAIT UNTIL rising_edge(clk); END LOOP;

    tb_end <= '1';

    WAIT;

  END PROCESS;

  ------------------------------------------------------------------------------

  -- DUT

  ------------------------------------------------------------------------------

  dut : ENTITY work.st_acc

  GENERIC MAP (

    g_dat_w            => g_dat_w,

    g_acc_w            => g_acc_w,

    g_hold_load        => g_hold_load,

    g_pipeline_input   => g_pipeline_input,

    g_pipeline_output  => g_pipeline_output

  )

  PORT MAP (

    clk        => clk,

    clken      => '1',

    in_load    => in_load,  -- start of accumulate period

    in_dat     => in_dat,

    in_acc     => in_acc,   -- use only one accumulator

    in_val     => in_val,

    out_acc    => out_acc,

    out_val    => out_val

  );

  in_acc <= out_acc WHEN c_pipeline>0 ELSE

            out_acc WHEN rising_edge(clk);  -- if DUT has no pipeline, then register feedback to avoid combinatorial loop

  ------------------------------------------------------------------------------

  -- Verify

  ------------------------------------------------------------------------------

  expected_acc <= func_acc(in_dat, in_acc, in_val, in_load);

  u_result : ENTITY common_components_lib.common_pipeline

  GENERIC MAP (

    g_representation => "SIGNED",

    g_pipeline       => c_pipeline,

    g_reset_value    => 0,

    g_in_dat_w       => g_acc_w,

    g_out_dat_w      => g_acc_w

  )

  PORT MAP (

    clk     => clk,

    clken   => '1',

    in_dat  => expected_acc,

    out_dat => expected_acc_p

  );

  p_verify : PROCESS(clk)

  BEGIN

    IF rising_edge(clk) THEN

      IF out_val='1' THEN

        ASSERT out_acc  = expected_acc_p REPORT "Error: wrong result" SEVERITY ERROR;

      END IF;

    END IF;

  END PROCESS;

END tb;