clk_gen.v

精简CPU设计

module clk_gen(clk,reset,clk1,clk2,clk4,fetch,alu_clk);
    input clk,reset;
    output clk1,clk2,clk4,fetch,alu_clk;
    wire clk;
    reg clk2,clk4,fetch,alu_clk;
    reg[7:0] state;
    parameter  S1=8'b0000_0001,
               S2=8'b0000_0010,
               S3=8'b0000_0100,
               S4=8'b0000_1000,
               S5=8'b0001_0000,
               S6=8'b0010_0000,
               S7=8'b0100_0000,
               S8=8'b1000_0000,
             idle=8'b0000_0000;
             
    assign clk1=~clk;
    
    always @(negedge clk)
      if(!reset)
         begin
            clk2<=0;
            clk4<=1;
            fetch<=0;
            alu_clk<=0;
            state<=idle;
         end
      else
        begin
            case(state)
                S1:
                    begin
                       clk2<=~clk2;
                    //   alu_clk<=~alu_clk;
                       state<=S2;
                    end
                S2:
                    begin
                        clk2<=~clk2;
                        clk4<=~clk4;
                      //  alu_clk<=~alu_clk;
                        state<=S3;
                    end
                S3:
                    begin
                        clk2<=~clk2;
                        state<=S4;
                    end
                S4:
                    begin
                        clk2<=~clk2;
                        clk4<=~clk4;
                        fetch<=~fetch;
                        state<=S5;
                    end
                S5:
                    begin
                        clk2<=~clk2;
                        state<=S6;
                        
                    end
                S6:
                    begin
                        clk2<=~clk2;
                        clk4<=~clk4;
                        alu_clk<=~alu_clk;
                        state<=S7;
                    end
                S7:
                    begin
                        clk2<=~clk2;
                        state<=S8;
                        alu_clk<=~alu_clk;
                    end
                S8:
                    begin
                        clk2<=~clk2;
                        clk4<=~clk4;
                        fetch<=~fetch;
                        state<=S1;
                    end
                idle: state<=S1;
                default: state<=idle;
                
           endcase
       end
endmodule