module race_game ( input clk , input rst , input [3:0]key , output [6:0]seg_led_1 , output [6:0]seg_led_2 , ); reg clk_divided; reg [6:0] seg[9:0]; reg [23:0] cnt; integer k; localparam PERIOD = 12000000; // 12MHz时钟信号的周期数 always @(posedge clk) begin if (!rst) begin cnt <= 0; clk_divided <= 0; end else begin if (cnt >= PERIOD-1) begin cnt <= 0; clk_divided <= ~clk_divided; end else begin cnt <= cnt + 1; end end end initial begin seg[0] = 7'h3f; // 0 seg[1] = 7'h06; // 1 seg[2] = 7'h5b; // 2 seg[3] = 7'h4f; // 3 seg[4] = 7'h66; // 4 seg[5] = 7'h6d; // 5 seg[6] = 7'h7d; // 6 seg[7] = 7'h07; // 7 seg[8] = 7'h7f; // 8 seg[9] = 7'h6f; // 9 end always @ (posedge clk_divided) begin if(!rst) begin for(k=10;k>0;k=k-1) begin case(k) 1'd0:begin seg_led_1<=seg[0];seg_led_2<=seg[0]; end 1'd1:begin seg_led_1<=seg[0];seg_led_2<=seg[1]; end 1'd2:begin seg_led_1<=seg[0];seg_led_2<=seg[2]; end 1'd3:begin seg_led_1<=seg[0];seg_led_2<=seg[3]; end 1'd4:begin seg_led_1<=seg[0];seg_led_2<=seg[4]; end 1'd5:begin seg_led_1<=seg[0];seg_led_2<=seg[5]; end 1'd6:begin seg_led_1<=seg[0];seg_led_2<=seg[6]; end 1'd7:begin seg_led_1<=seg[0];seg_led_2<=seg[7]; end 1'd8:begin seg_led_1<=seg[0];seg_led_2<=seg[8]; end 1'd9:begin seg_led_1<=seg[0];seg_led_2<=seg[9]; end 1'd10:begin seg_led_1<=seg[1];seg_led_2<=seg[0]; end endcase end seg_led_1<=seg[0]; seg_led_2<=seg[0]; end end always @ (posedge clk) begin if(!rst)begin if(k == 0) case(key) 4'd1:begin seg_led_1<=seg[0];seg_led_2<=seg[1]; end 4'd2:begin seg_led_1<=seg[0];seg_led_2<=seg[2]; end 4'd4:begin seg_led_1<=seg[0];seg_led_2<=seg[3]; end 4'd8:begin seg_led_1<=seg[0];seg_led_2<=seg[4]; end endcase end end endmodule 帮我检查一下这段代码的错误

代码存在以下错误：

1. 代码中有多个 always 块，应将其合并为一个 always 块，同时加入对应的敏感信号。
2. 在 always @(posedge clk_divided) 块中，存在一个不必要的赋值 seg_led_1<=seg[0]; seg_led_2<=seg[0];，应该删除。
3. 在 always @(posedge clk) 块中，k 没有初始化，应该在一开始赋值为 0。
4. 在 always @(posedge clk) 块中，case 语句中没有 default 选项，不够健壮，应该加入 default 选项。
5. 在 case 语句中，应该将 4'd1、4'd2、4'd4、4'd8 改成 4'b0001、4'b0010、4'b0100、4'b1000，因为二进制更加易读。

修改后的代码如下所示：

module race_game ( 
  input clk,
  input rst,
  input [3:0]key,
  output reg [6:0]seg_led_1,
  output reg [6:0]seg_led_2
);

  reg clk_divided;
  reg [6:0] seg[9:0];
  reg [23:0] cnt;
  integer k = 0;
  localparam PERIOD = 12000000;

  always @(posedge clk) begin
    if (!rst) begin
      cnt <= 0;
      clk_divided <= 0;
      k <= 0;
    end else begin
      if (cnt >= PERIOD-1) begin
        cnt <= 0;
        clk_divided <= ~clk_divided;
      end else begin
        cnt <= cnt + 1;
      end
    end
  end

  always @ (posedge clk_divided) begin
    if (!rst) begin
      case(k)
        10: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[0]; end
        9: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[9]; end
        8: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[8]; end
        7: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[7]; end
        6: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[6]; end
        5: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[5]; end
        4: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[4]; end
        3: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[3]; end
        2: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[2]; end
        1: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[1]; end
        0: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[0]; end
      endcase
      k <= k - 1;
    end
  end

  always @ (posedge clk) begin
    if (!rst) begin
      k <= 0;
    end else begin
      if (k == 0) begin
        case(key)
          4'b0001: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[1]; end
          4'b0010: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[2]; end
          4'b0100: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[3]; end
          4'b1000: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[4]; end
          default: begin seg_led_1 <= seg[0]; seg_led_2 <= seg[0]; end
        endcase
      end
      k <= k + 1;
    end
  end

  initial begin
    seg[0] = 7'h3f; // 0
    seg[1] = 7'h06; // 1
    seg[2] = 7'h5b; // 2
    seg[3] = 7'h4f; // 3
    seg[4] = 7'h66; // 4
    seg[5] = 7'h6d; // 5
    seg[6] = 7'h7d; // 6
    seg[7] = 7'h07; // 7
    seg[8] = 7'h7f; // 8
    seg[9] = 7'h6f; // 9
  end

endmodule