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https://github.com/antonblanchard/microwatt.git
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fa4baa2800
Jacob Lifshay found a couple of issues with the PLRU implementation: - The tree array is one bit too long. This is harmless as this bit is never accessed and thus should be optimized out - The PLRU read is using the wrong nodes when going down the tree, which leads to incorrect results. This fixes it and improves the test bench a bit. I have verified the expected output using a hand-written tree states, observed the mismatch with the current implementation and verified the fix. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
131 lines
3.0 KiB
VHDL
131 lines
3.0 KiB
VHDL
library vunit_lib;
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context vunit_lib.vunit_context;
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library ieee;
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use ieee.std_logic_1164.all;
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library work;
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use work.common.all;
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use work.wishbone_types.all;
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entity plru_tb is
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generic (runner_cfg : string := runner_cfg_default);
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end plru_tb;
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architecture behave of plru_tb is
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signal clk : std_ulogic;
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signal rst : std_ulogic;
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constant clk_period : time := 10 ns;
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signal acc_en : std_ulogic;
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signal acc : std_ulogic_vector(2 downto 0);
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signal lru : std_ulogic_vector(2 downto 0);
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begin
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plru0: entity work.plru
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generic map(
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BITS => 3
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)
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port map(
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clk => clk,
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rst => rst,
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acc => acc,
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acc_en => acc_en,
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lru => lru
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);
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clk_process: process
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begin
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clk <= '0';
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wait for clk_period/2;
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clk <= '1';
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wait for clk_period/2;
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end process;
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rst_process: process
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begin
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rst <= '1';
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wait for 2*clk_period;
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rst <= '0';
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wait;
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end process;
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stim: process
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begin
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test_runner_setup(runner, runner_cfg);
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wait for 8*clk_period;
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info("reset state:" & to_hstring(lru));
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check_equal(lru, 0, result("LRU"));
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info("accessing 1:");
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acc <= "001";
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acc_en <= '1';
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 4, result("LRU"));
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info("accessing 2:");
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acc <= "010";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 4, result("LRU"));
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info("accessing 7:");
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acc <= "111";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 0, result("LRU"));
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info("accessing 4:");
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acc <= "100";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 0, result("LRU"));
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info("accessing 3:");
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acc <= "011";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 6, result("LRU"));
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info("accessing 5:");
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acc <= "101";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 0, result("LRU"));
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info("accessing 3:");
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acc <= "011";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 6, result("LRU"));
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info("accessing 5:");
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acc <= "101";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 0, result("LRU"));
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info("accessing 6:");
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acc <= "110";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 0, result("LRU"));
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info("accessing 0:");
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acc <= "000";
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wait for clk_period;
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info("lru:" & to_hstring(lru));
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check_equal(lru, 4, result("LRU"));
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wait for clk_period;
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wait for clk_period;
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test_runner_cleanup(runner);
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end process;
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end;
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