给出用verilog语言实现以下功能的代码：由按键KEY0、KEY1控制计数器的值并在数码管上显示，每按下抬起一次KEY0计数加1，每按下抬起一次KEY1计数减1，计数加到100时归零，按照十进制在数码管的两位上显示,按下复位按钮后计数归零，其中两数码管为共阴极，并给出响应的检测其功能的testbentch测试文件代码

下面是用verilog语言实现上述功能的代码：

module counter(
    input clk, // 时钟信号
    input rst, // 复位信号
    input key0, // 按键KEY0
    input key1, // 按键KEY1
    output reg [6:0] seg // 数码管
);

reg [6:0] count; // 计数器
reg [1:0] display; // 显示数值

// 数码管的真值表
always @ (display)
    case (display)
        2'b00: seg = 7'b1000000; // 数码0
        2'b01: seg = 7'b1111001; // 数码1
        2'b10: seg = 7'b0100100; // 数码2
        2'b11: seg = 7'b0110000; // 数码3
    endcase

// 计数器的增减逻辑
always @ (posedge clk, posedge rst)
    if (rst) begin
        count <= 0;
    end else if (key0) begin
        if (count < 100) count <= count + 1;
        else count <= 0;
    end else if (key1) begin
        if (count > 0) count <= count - 1;
        else count <= 100;
    end

// 显示数值的逻辑
always @ (count)
    if (count < 10) display <= 2'b00;
    else if (count < 100) display <= 2'b10;
    else display <= 2'b00;

endmodule

下面是测试文件的代码：

module counter_tb;

reg clk;
reg rst;
reg key0;
reg key1;
wire [6:0] seg;

counter uut (
    .clk(clk),
    .rst(rst),
    .key0(key0),
    .key1(key1),
    .seg(seg)
);

initial begin
    clk = 0;
    forever #5 clk = ~clk;
end

initial begin
    rst = 1;
    key0 = 0;
    key1 = 0;
    #10 rst = 0;
end

initial begin
    #20 key0 = 1;
    #25 key0 = 0;
    #30 key1 = 1;
    #35 key1 = 0;
    #40 key0 = 1;
    #45 key0 = 0;
    #50 key1 = 1;
    #55 key1 = 0;
    #60 key0 = 1;
    #65 key0 = 0;
    #70 key1 = 1;
    #75 key1 = 0;
    #80 key0 = 1;
    #85 key0 = 0;
    #90 key1 = 1;
    #95 key1 = 0;
    #100 key0 = 1;
    #105 key0 = 0;
    #110 key1 = 1;
    #115 key1 = 0;
    #120 key0 = 1;
    #125 key0 = 0;
    #130 key1 = 1;
    #135 key1 = 0;
    #140 key0 = 1;
    #145 key0 = 0;
    #150 key1 = 1;
    #155 key1 = 0;
    #160 key0 = 1;
    #165 key0 = 0;
    #170 key1 = 1;
    #175 key1 = 0;
    #180 key0 = 1;
    #185 key0 = 0;
    #190 key1 = 1;
    #195 key1 = 0;
    #200 key0 = 1;
    #205 key0 = 0;
    #210 key1 = 1;
    #215 key1 = 0;
    #220 key0 = 1;
    #225 key0 = 0;
    #230 key1 = 1;
    #235 key1 = 0;
    #240 key0 = 1;
    #245 key0 = 0;
    #250 key1 = 1;
    #255 key1 = 0;
    #260 key0 = 1;
    #265 key0 = 0;
    #270 key1 = 1;
    #275 key1 = 0;
    #280 key0 = 1;
    #285 key0 = 0;
    #290 key1 = 1;
    #295 key1 = 0;
    #300 key0 = 1;
    #305 key0 = 0;
    #310 key1 = 1;
    #315 key1 = 0;
    #320 key0 = 1;
    #325 key0 = 0;
    #330 key1 = 1;
    #335 key1 = 0;
    #340 key0 = 1;
    #345 key0 = 0;
    #350 key1 = 1;
    #355 key1 = 0;
    #360 key0 = 1;
    #365 key0 = 0;
    #370 key1 = 1;
    #375 key1 = 0;
    #380 key0 = 1;
    #385 key0 = 0;
    #390 key1 = 1;
    #395 key1 = 0;
    #400 key0 = 1;
    #405 key0 = 0;
    #410 key1 = 1;
    #415 key1 = 0;
    #420 key0 = 1;
    #425 key0 = 0;
    #430 key1 = 1;
    #435 key1 = 0;
    #440 key0 = 1;
    #445 key0 = 0;
    #450 key1 = 1;
    #455 key1 = 0;
    #460 key0 = 1;
    #465 key0 = 0;
    #470 key1 = 1;
    #475 key1 = 0;
    #480 key0 = 1;
    #485 key0 = 0;
    #490 key1 = 1;
    #495 key1 = 0;
    #500 key0 = 1;
    #505 key0 = 0;
    #510 key1 = 1;
    #515 key1 = 0;
end

endmodule

测试文件中模拟了按键的操作，按键按下的时间为5个时钟周期，然后再抬起，因此按键的控制时间间隔为10个时钟周期。在仿真过程中，可以观察数码管上的数值变化，以检测计数器的功能是否正常。