Verilog 一个流水线控制模式的程序

以下是一个简单的基于流水线控制模式的 Verilog 程序示例：

module pipeline_control (
  input clk, // 时钟信号
  input reset, // 复位信号
  input start, // 启动信号
  output done // 完成信号
);

  // 状态定义
  parameter IDLE = 0, FETCH = 1, DECODE = 2, EXECUTE = 3, WRITEBACK = 4;
  reg [3:0] state, next_state;

  // 控制信号定义
  reg fetch_enable, decode_enable, execute_enable, writeback_enable;

  // 状态寄存器定义
  reg [31:0] pc, instruction, opcode, operand1, operand2, result, address;

  // 流水线寄存器定义
  reg [31:0] fetch_reg, decode_reg, execute_reg, writeback_reg;

  always @(posedge clk) begin
    if (reset) begin
      // 复位时进入 IDLE 状态
      state <= IDLE;
      fetch_enable <= 0;
      decode_enable <= 0;
      execute_enable <= 0;
      writeback_enable <= 0;
    end else begin
      // 状态转移逻辑
      state <= next_state;
      fetch_enable <= (state == FETCH);
      decode_enable <= (state == DECODE);
      execute_enable <= (state == EXECUTE);
      writeback_enable <= (state == WRITEBACK);
    end
  end

  always @(state or fetch_reg or decode_reg or execute_reg or writeback_reg) begin
    case (state)
      IDLE: begin
        // 空闲状态，等待启动信号
        next_state = start ? FETCH : IDLE;
      end
      FETCH: begin
        // 取指令阶段
        fetch_reg <= $readmemh("program.hex", pc);
        next_state = DECODE;
      end
      DECODE: begin
        // 解码阶段
        opcode <= fetch_reg[31:24];
        operand1 <= fetch_reg[23:16];
        operand2 <= fetch_reg[15:8];
        address <= fetch_reg[7:0];
        next_state = EXECUTE;
      end
      EXECUTE: begin
        // 执行阶段
        case (opcode)
          0: result <= operand1 + operand2; // 加法
          1: result <= operand1 - operand2; // 减法
          2: result <= operand1 & operand2; // 按位与
          3: result <= operand1 | operand2; // 按位或
          4: result <= operand1 ^ operand2; // 按位异或
          5: result <= operand1 << operand2; // 逻辑左移
          6: result <= operand1 >> operand2; // 逻辑右移
          7: result <= $readmemh("memory.hex", address); // 读内存
          8: $writememh("memory.hex", address, operand1); // 写内存
          default: result <= 0; // 未知指令
        endcase
        next_state = WRITEBACK;
      end
      WRITEBACK: begin
        // 写回阶段
        writeback_reg <= result;
        next_state = FETCH;
      end
    endcase
  end

  // 完成信号
  assign done = (state == IDLE);

endmodule

这个程序实现了一个基于 5 个阶段的流水线控制模式，包括取指令、解码、执行、写回和空闲状态。在执行阶段，根据指令类型进行相应的计算或内存读写操作，并将结果写回到流水线寄存器中。然后在写回阶段，将结果写回到内存中。最后，完成信号在 IDLE 状态下被设置为高电平，表示程序已经执行完毕。