三选一数据选择器modelsim仿真代码和测试代码

以下是一个三选一的数据选择器的Verilog代码和测试代码，可以在ModelSim中进行仿真：

module mux_3to1(input [2:0] data_in, input [1:0] sel, output reg data_out);

always @ (sel or data_in)
begin
    case(sel)
        2'b00: data_out = data_in[0];
        2'b01: data_out = data_in[1];
        2'b10: data_out = data_in[2];
        2'b11: data_out = 1'b0; // if sel is invalid, output 0
    endcase
end

endmodule

测试代码：

module test_mux_3to1();

reg [2:0] data_in;
reg [1:0] sel;
wire data_out;

mux_3to1 uut(
    .data_in(data_in),
    .sel(sel),
    .data_out(data_out)
);

initial begin
    // Test case 1: sel = 0, expect data_out = data_in[0]
    data_in = 3'b001;
    sel = 2'b00;
    #10;
    if (data_out !== 1'b0) $error("Test case 1 failed: data_out = %b", data_out);
    sel = 2'b01;
    #10;
    if (data_out !== 1'b0) $error("Test case 1 failed: data_out = %b", data_out);
    sel = 2'b10;
    #10;
    if (data_out !== 1'b1) $error("Test case 1 failed: data_out = %b", data_out);
    sel = 2'b11;
    #10;
    if (data_out !== 1'b0) $error("Test case 1 failed: data_out = %b", data_out);

    // Test case 2: sel = 1, expect data_out = data_in[1]
    data_in = 3'b110;
    sel = 2'b01;
    #10;
    if (data_out !== 1'b1) $error("Test case 2 failed: data_out = %b", data_out);
    sel = 2'b00;
    #10;
    if (data_out !== 1'b0) $error("Test case 2 failed: data_out = %b", data_out);
    sel = 2'b10;
    #10;
    if (data_out !== 1'b0) $error("Test case 2 failed: data_out = %b", data_out);
    sel = 2'b11;
    #10;
    if (data_out !== 1'b0) $error("Test case 2 failed: data_out = %b", data_out);

    // Test case 3: sel = 2, expect data_out = data_in[2]
    data_in = 3'b010;
    sel = 2'b10;
    #10;
    if (data_out !== 1'b0) $error("Test case 3 failed: data_out = %b", data_out);
    sel = 2'b00;
    #10;
    if (data_out !== 1'b0) $error("Test case 3 failed: data_out = %b", data_out);
    sel = 2'b01;
    #10;
    if (data_out !== 1'b1) $error("Test case 3 failed: data_out = %b", data_out);
    sel = 2'b11;
    #10;
    if (data_out !== 1'b0) $error("Test case 3 failed: data_out = %b", data_out);

    // Test case 4: sel = 3, expect data_out = 0
    data_in = 3'b111;
    sel = 2'b11;
    #10;
    if (data_out !== 1'b0) $error("Test case 4 failed: data_out = %b", data_out);
    sel = 2'b00;
    #10;
    if (data_out !== 1'b0) $error("Test case 4 failed: data_out = %b", data_out);
    sel = 2'b01;
    #10;
    if (data_out !== 1'b0) $error("Test case 4 failed: data_out = %b", data_out);
    sel = 2'b10;
    #10;
    if (data_out !== 1'b0) $error("Test case 4 failed: data_out = %b", data_out);

    $display("All test cases passed!");
    $finish;
end

endmodule