用verilog写axi4的握手通道

AXI4协议中的握手通道主要包括信号`AWVALID`、`AWREADY`、`WVALID`、`WREADY`、`BVALID`、`BREADY`、`ARVALID`、`ARREADY`、`RVALID`和`RREADY`。以下是一个基本的AXI4握手通道的Verilog实现：

module axi4_handshake(
  input  logic         aclk,
  input  logic         aresetn,
  input  logic [31:0]  awaddr,
  input  logic [2:0]   awprot,
  input  logic         awvalid,
  output logic         awready,
  input  logic [31:0]  wdata,
  input  logic [3:0]   wstrb,
  input  logic         wvalid,
  output logic         wready,
  output logic [1:0]   bresp,
  output logic         bvalid,
  input  logic         bready,
  input  logic [31:0]  araddr,
  input  logic [2:0]   arprot,
  input  logic         arvalid,
  output logic         arready,
  output logic [1:0]   rresp,
  output logic [31:0]  rdata,
  output logic         rvalid,
  input  logic         rready
);

  localparam IDLE = 2'b00, ADDR = 2'b01, DATA = 2'b10, RESP = 2'b11;
  logic [1:0] state, next_state;
  logic [31:0] addr_reg, wdata_reg, rdata_reg;
  logic [1:0] bresp_reg, rresp_reg;
  logic [3:0] wstrb_reg;

  // 状态寄存器初始化
  always_ff @(posedge aclk, negedge aresetn) begin
    if (!aresetn) begin
      state <= IDLE;
    end else begin
      state <= next_state;
    end
  end

  // 地址、写数据、读数据寄存器初始化
  always_ff @(posedge aclk, negedge aresetn) begin
    if (!aresetn) begin
      addr_reg <= 0;
      wdata_reg <= 0;
      rdata_reg <= 0;
    end else begin
      if (awvalid && awready) begin
        addr_reg <= awaddr;
      end
      if (wvalid && wready) begin
        wdata_reg <= wdata;
        wstrb_reg <= wstrb;
      end
      if (rvalid && rready) begin
        rdata_reg <= rdata;
      end
    end
  end

  // 响应寄存器初始化
  always_ff @(posedge aclk, negedge aresetn) begin
    if (!aresetn) begin
      bresp_reg <= 0;
      rresp_reg <= 0;
    end else begin
      if (bvalid && bready) begin
        bresp_reg <= bresp;
      end
      if (rvalid && rready) begin
        rresp_reg <= rresp;
      end
    end
  end

  // AWREADY信号
  assign awready = (state == IDLE) || (state == RESP);

  // WREADY信号
  assign wready = (state == DATA);

  // BVALID信号
  assign bvalid = (state == RESP);

  // ARREADY信号
  assign arready = (state == IDLE) || (state == RESP);

  // RVALID信号
  assign rvalid = (state == RESP);

  // 下一个状态
  always_comb begin
    case (state)
      IDLE: begin
        if (awvalid && awready) begin
          next_state = ADDR;
        end else if (arvalid && arready) begin
          next_state = ADDR;
        end else begin
          next_state = IDLE;
        end
      end
      ADDR: begin
        if (wvalid && wready) begin
          next_state = DATA;
        end else if (arvalid && arready) begin
          next_state = RESP;
        end else begin
          next_state = ADDR;
        end
      end
      DATA: begin
        if (wvalid && wready) begin
          next_state = RESP;
        end else begin
          next_state = DATA;
        end
      end
      RESP: begin
        if (bvalid && bready) begin
          next_state = IDLE;
        end else if (rvalid && rready) begin
          next_state = IDLE;
        end else begin
          next_state = RESP;
        end
      end
      default: begin
        next_state = IDLE;
      end
    endcase
  end

  // AXI4 AW信号
  axi4_aw aw_inst (
    .aclk(aclk),
    .aresetn(aresetn),
    .awaddr(addr_reg),
    .awprot(awprot),
    .awvalid(awvalid),
    .awready(awready)
  );

  // AXI4 W信号
  axi4_w w_inst (
    .aclk(aclk),
    .aresetn(aresetn),
    .wdata(wdata_reg),
    .wstrb(wstrb_reg),
    .wvalid(wvalid),
    .wready(wready)
  );

  // AXI4 B信号
  axi4_b b_inst (
    .aclk(aclk),
    .aresetn(aresetn),
    .bresp(bresp_reg),
    .bvalid(bvalid),
    .bready(bready)
  );

  // AXI4 AR信号
  axi4_ar ar_inst (
    .aclk(aclk),
    .aresetn(aresetn),
    .araddr(addr_reg),
    .arprot(arprot),
    .arvalid(arvalid),
    .arready(arready)
  );

  // AXI4 R信号
  axi4_r r_inst (
    .aclk(aclk),
    .aresetn(aresetn),
    .rdata(rdata_reg),
    .rresp(rresp_reg),
    .rvalid(rvalid),
    .rready(rready)
  );

endmodule

代码中使用了4个状态机来处理不同的操作，分别是`IDLE`、`ADDR`、`DATA`和`RESP`状态。在`IDLE`状态中，如果接收到`AWVALID`或`ARVALID`信号，则进入`ADDR`状态；在`ADDR`状态中，如果接收到`WVALID`信号，则进入`DATA`状态，如果接收到`ARVALID`信号，则进入`RESP`状态；在`DATA`状态中，如果接收到`WVALID`信号，则继续保持在`DATA`状态，否则进入`RESP`状态；在`RESP`状态中，如果接收到`BVALID`或`RVALID`信号，则回到`IDLE`状态，否则继续保持在`RESP`状态。

此外，代码中还包括了AXI4协议中的各个信号的输入输出端口，并将其连接到实例化的AXI4模块中。由于涉及到具体的协议细节，代码中省略了一些细节处理，需要根据具体的应用进行修改。