Stateful Goroutines in VHDL

Our example demonstrates a stateful process using VHDL. In VHDL, we don’t have direct equivalents to goroutines or channels, but we can use processes and signals to achieve similar functionality.

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity StatefulProcess is
end StatefulProcess;

architecture Behavioral of StatefulProcess is
    type state_type is array (0 to 4) of integer;
    signal state : state_type := (others => 0);
    
    signal read_key : integer range 0 to 4;
    signal read_value : integer;
    signal write_key : integer range 0 to 4;
    signal write_value : integer;
    signal write_enable : std_logic := '0';
    
    signal read_ops, write_ops : unsigned(31 downto 0) := (others => '0');
begin
    -- This process owns the state and handles read/write operations
    state_process: process(read_key, write_key, write_value, write_enable)
    begin
        if write_enable = '1' then
            state(write_key) <= write_value;
        end if;
        read_value <= state(read_key);
    end process;

    -- This process simulates multiple read operations
    read_process: process
    begin
        for i in 0 to 99 loop
            read_key <= i mod 5;
            wait for 1 ms;
            read_ops <= read_ops + 1;
        end loop;
        wait;
    end process;

    -- This process simulates multiple write operations
    write_process: process
    begin
        for i in 0 to 9 loop
            write_key <= i mod 5;
            write_value <= i * 10;
            write_enable <= '1';
            wait for 1 ns;
            write_enable <= '0';
            wait for 1 ms;
            write_ops <= write_ops + 1;
        end loop;
        wait;
    end process;

    -- This process reports the final operation counts
    report_process: process
    begin
        wait for 1 sec;
        report "Read operations: " & integer'image(to_integer(read_ops));
        report "Write operations: " & integer'image(to_integer(write_ops));
        wait;
    end process;

end Behavioral;

In this VHDL example, we’ve created a stateful process that manages a small array (our “state”). We use separate processes to simulate multiple concurrent read and write operations, similar to the goroutines in the original example.

The state_process owns the state and handles read and write operations. The read_process and write_process simulate multiple concurrent operations by repeatedly reading from or writing to the state.

We use signals to communicate between processes, which is somewhat analogous to using channels in the original example. The read_key, read_value, write_key, write_value, and write_enable signals are used to pass information between the operation processes and the state process.

We keep track of the number of read and write operations using the read_ops and write_ops signals, which are incremented in their respective processes.

Finally, the report_process waits for one second (simulating the sleep in the original example) and then reports the total number of read and write operations.

To run this VHDL code, you would typically use a VHDL simulator like ModelSim or GHDL. The exact commands would depend on your specific environment and tools.

This VHDL implementation captures the essence of the original example, demonstrating a way to manage shared state in a concurrent environment, albeit using VHDL’s process-based concurrency model rather than goroutines.

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Stateful Goroutines in VHDL