写出完整的全握手协议的Verilog代码

下面是一个简单的Verilog代码示例，实现了基于Verilog全握手协议的数据传输：

module handshake_protocol (
    input clk,
    input rst,
    input req,
    output reg ack,
    input [7:0] data_in,
    output reg [7:0] data_out
);

// 状态机定义
typedef enum logic [1:0] {
    IDLE,
    REQ_SENT,
    ACK_SENT,
    DATA_SENT,
    DATA_RECEIVED
} state_t;

reg [1:0] state = IDLE;

// 初始化
always @(posedge clk, posedge rst) begin
    if (rst) begin
        ack <= 0;
        data_out <= 0;
        state <= IDLE;
    end else begin
        case(state)
            IDLE: begin
                ack <= 0;
                data_out <= 0;
                if (req) begin
                    state <= REQ_SENT;
                end
            end
            REQ_SENT: begin
                ack <= 1;
                data_out <= 0;
                if (!req) begin
                    state <= ACK_SENT;
                end
            end
            ACK_SENT: begin
                ack <= 0;
                data_out <= data_in;
                state <= DATA_SENT;
            end
            DATA_SENT: begin
                ack <= 1;
                data_out <= data_in;
                if (!req) begin
                    state <= DATA_RECEIVED;
                end
            end
            DATA_RECEIVED: begin
                ack <= 0;
                data_out <= 0;
                state <= IDLE;
            end
        endcase
    end
end

endmodule

在这个Verilog代码中，我们定义了一个状态机，包含了五个状态：IDLE、REQ_SENT、ACK_SENT、DATA_SENT和DATA_RECEIVED。设备A通过req信号发送请求，设备B通过ack信号发送确认。一旦收到确认，设备A将发送数据，设备B将确认数据接收。最后，设备A和设备B都将回到初始状态，等待下一次请求。

请注意，此代码仅为演示目的，可能需要进行修改以适应您的特定应用场景。