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
            case({set,boost})
                2'b11,
                2'b10: remain <= remain + money;
                2'b00: remain <= (remain=='d0)?'d0:(remain-'d1);
                2'b01: remain <= (remain>='d2)?(remain-'d2):remain;
                default: remain <= remain;
            endcase
        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