verilog语言四层电梯

以下是一个简单的四层电梯的verilog代码实现：

module elevator(
    input clk,
    input reset,
    input [1:0] floor_req,
    input up,
    input down,
    output [1:0] current_floor
);

reg [1:0] current_floor;
reg [1:0] next_floor;
reg [1:0] floor_mask;
reg up_pressed;
reg down_pressed;

parameter idle = 2'b00;
parameter moving_up = 2'b01;
parameter moving_down = 2'b10;

//设置当前楼层为1楼
initial current_floor = 2'b01;

//设置电梯状态为 idle
reg [1:0] state = idle;

always @(posedge clk) begin
    if (reset) begin
        // 重置电梯状态为 idle
        state <= idle;
        floor_mask <= 2'b00;
    end else begin
        case (state)
            idle: begin
                if (floor_req != 2'b00) begin
                    if (floor_req > current_floor) begin
                        next_floor <= floor_req;
                        state <= moving_up;
                    end else if (floor_req < current_floor) begin
                        next_floor <= floor_req;
                        state <= moving_down;
                    end
                end
            end
            moving_up: begin
                // 电梯上升
                current_floor <= current_floor + 1;
                // 到达目标楼层
                if (current_floor == next_floor) begin
                    // 打开电梯门，并清除该楼层的请求
                    floor_mask <= floor_mask & ~(1 << (current_floor - 1));
                    // 如果还有请求，继续移动
                    if (floor_mask != 2'b00) begin
                        next_floor <= $ffs(floor_mask) - 1;
                    end else begin
                        state <= idle;
                    end
                end
            end
            moving_down: begin
                // 电梯下降
                current_floor <= current_floor - 1;
                // 到达目标楼层
                if (current_floor == next_floor) begin
                    // 打开电梯门，并清除该楼层的请求
                    floor_mask <= floor_mask & ~(1 << (current_floor - 1));
                    // 如果还有请求，继续移动
                    if (floor_mask != 2'b00) begin
                        next_floor <= $clog2(floor_mask) - 1;
                    end else begin
                        state <= idle;
                    end
                end
            end
        endcase
    end
end

// 按下上行或下行按钮
always @(*) begin
    if (up) begin
        up_pressed = 1;
    end else if (down) begin
        down_pressed = 1;
    end else begin
        up_pressed = 0;
        down_pressed = 0;
    end
end

// 处理楼层请求
always @(*) begin
    if (up_pressed || down_pressed) begin
        // 设置请求位
        floor_mask <= floor_mask | (1 << (floor_req - 1));
        // 如果电梯处于空闲状态，则开始移动
        if (state == idle) begin
            if (up_pressed) begin
                next_floor <= $ffs(floor_mask) - 1;
                state <= moving_up;
            end else if (down_pressed) begin
                next_floor <= $clog2(floor_mask) - 1;
                state <= moving_down;
            end
        end
    end
end

endmodule

该代码实现了一个简单的四层电梯，包含了上行、下行、楼层请求、电梯状态等功能。