题解 | #游戏机计费程序#

`timescale 1ns/1ns

module game_count
    (
		input rst_n, //异位复位信号，低电平有效
        input clk, 	//时钟信号
        input [9:0]money,
        input set,
		input boost,
		output reg[9:0]remain,
		output reg yellow,
		output reg red
    );
    always@(posedge clk or negedge rst_n) begin
        if(!rst_n) begin
            remain <= 'd0;
        end
        else begin
            if(set) begin
                remain <= remain + money;
            end
            else if(boost) begin
                if(remain>0)
                    remain <= remain - 'd2;
                else
                    remain <= remain;
            end
            else if(!boost) begin
                if(remain>0)
                    remain <= remain - 'd1;
                else
                    remain <= remain;
            end
            else begin
                remain <= remain;
            end
        end
    end
    always@(posedge clk or negedge rst_n) begin
        if(!rst_n) begin
            yellow <= 1'b0;
            red <= 1'b0;
        end
        else begin
            yellow <= (remain <'d10) & (remain >'d0);
            red <= (remain=='d0);
        end
    end
endmodule