Stateful Goroutines in Verilog

Our example demonstrates a simple state machine implemented in Verilog. While Verilog doesn’t have direct equivalents to Go’s goroutines or channels, we can model similar behavior using a state machine and registers.

module StatefulMachine (
    input wire clk,
    input wire reset,
    input wire [2:0] read_key,
    input wire [2:0] write_key,
    input wire [7:0] write_val,
    input wire read_request,
    input wire write_request,
    output reg [7:0] read_result,
    output reg read_valid,
    output reg write_done
);

    // Define states
    localparam IDLE = 2'b00;
    localparam READ = 2'b01;
    localparam WRITE = 2'b10;

    reg [1:0] state;
    reg [7:0] memory [0:7];  // 8 locations, each 8 bits wide
    reg [31:0] read_ops;
    reg [31:0] write_ops;

    always @(posedge clk or posedge reset) begin
        if (reset) begin
            state <= IDLE;
            read_ops <= 0;
            write_ops <= 0;
            read_valid <= 0;
            write_done <= 0;
        end else begin
            case (state)
                IDLE: begin
                    read_valid <= 0;
                    write_done <= 0;
                    if (read_request) begin
                        state <= READ;
                    end else if (write_request) begin
                        state <= WRITE;
                    end
                end

                READ: begin
                    read_result <= memory[read_key];
                    read_valid <= 1;
                    read_ops <= read_ops + 1;
                    state <= IDLE;
                end

                WRITE: begin
                    memory[write_key] <= write_val;
                    write_done <= 1;
                    write_ops <= write_ops + 1;
                    state <= IDLE;
                end
            endcase
        end
    end

endmodule

In this Verilog implementation:

1. We define a module StatefulMachine that represents our state-owning entity.

2. The module has inputs for read and write requests, including keys and values, and outputs for read results and operation completion signals.

3. We use a simple state machine with three states: IDLE, READ, and WRITE.

4. The memory array simulates the map in the Go version, storing 8-bit values at 8 different locations.

5. read_ops and write_ops counters keep track of the number of read and write operations performed.

6. In each clock cycle, the module checks for read or write requests and transitions to the appropriate state.

7. Read operations fetch the value from memory and set the read_valid signal.

8. Write operations update the memory and set the write_done signal.

9. After each operation, the state machine returns to the IDLE state.

This Verilog implementation provides a similar functionality to the Go example, managing shared state in a controlled manner. However, it’s important to note that this is a simplified, synchronous design and doesn’t directly replicate the concurrency model of Go. In a real Verilog design, you might need additional logic for handling multiple simultaneous requests or implementing more complex behaviors.

To use this module, you would instantiate it in a testbench or a larger design, providing clock and reset signals, and driving the input signals to perform read and write operations. The results can be observed through the output signals.