Channel Synchronization in Verilog

This example demonstrates how to use a simple handshake mechanism in Verilog to synchronize execution between two processes. This is analogous to channel synchronization in concurrent programming languages.

module channel_synchronization;
  reg clk;
  reg reset;
  reg start;
  wire done;

  // This is the "worker" module that performs some task
  worker w1 (
    .clk(clk),
    .reset(reset),
    .start(start),
    .done(done)
  );

  // Clock generation
  initial begin
    clk = 0;
    forever #5 clk = ~clk;
  end

  // Testbench
  initial begin
    $display("Starting simulation");
    reset = 1;
    start = 0;
    #10 reset = 0;
    
    // Start the worker
    #10 start = 1;
    #10 start = 0;
    
    // Wait for the worker to finish
    @(posedge done);
    
    $display("Worker has finished");
    $finish;
  end

endmodule

// This is the worker module
module worker (
  input wire clk,
  input wire reset,
  input wire start,
  output reg done
);
  reg [1:0] state;
  parameter IDLE = 2'b00, WORKING = 2'b01, FINISHED = 2'b10;

  always @(posedge clk or posedge reset) begin
    if (reset) begin
      state <= IDLE;
      done <= 0;
    end else begin
      case (state)
        IDLE: 
          if (start) begin
            $display("working...");
            state <= WORKING;
          end
        WORKING: begin
          // Simulate some work by waiting for 10 clock cycles
          if ($time % 100 == 0) begin
            $display("done");
            state <= FINISHED;
          end
        end
        FINISHED: begin
          done <= 1;
          state <= IDLE;
        end
      endcase
    end
  end
endmodule

In this Verilog example, we’ve created a simple synchronization mechanism between a testbench and a worker module. The worker module simulates a task that takes some time to complete, and the testbench waits for it to finish.

The worker module has a start input and a done output. When start is asserted, it begins its “work” (simulated by waiting for 10 clock cycles). When the work is complete, it asserts the done signal.

In the testbench, we start the worker by asserting the start signal, then wait for the done signal to be asserted before finishing the simulation.

This demonstrates a basic form of synchronization in hardware design, which is analogous to channel synchronization in software concurrency.

To run this Verilog code, you would typically use a Verilog simulator. The exact command would depend on your simulation environment, but it might look something like this:

$ iverilog -o channel_synchronization channel_synchronization.v
$ ./channel_synchronization
Starting simulation
working...
done
Worker has finished

This example shows how we can synchronize processes in hardware design, which is conceptually similar to synchronizing goroutines in concurrent programming.

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Channel Synchronization in Verilog