module decode(              //input              Signal_A,     // detect A              Signal_B,     // detect B			     Signal_C,     // detect C			     BIT_EN_temp,  // bit_enable when detect signal			     RESET,        // system reset			     //output			     DOUT,         // miller decode serial 			     DATA_EN,      // data_enable			     BIT_EN        // bit enable when detect effective signal			     );input  Signal_A,Signal_B,Signal_C,BIT_EN_temp,RESET;output DOUT,DATA_EN,BIT_EN;reg    DOUT,DATA_EN;//,BIT_EN// signal stateparameter A=2'b00,B=2'b01,C=2'b10;reg[1:0] last_flag;reg[1:0] current_flag;wire[3:0] full_flag;//wire Signal_det; // indicate we have a "A/B/C detect"// fsm 3 stateparameter idle = 2'b00, start = 2'b01, data = 2'b10;  reg[1:0] current_state;wire[1:0] next_state;//assign Signal_det = Signal_A|Signal_B|Signal_C;assign BIT_EN = BIT_EN_temp&DATA_EN;/*always @(BIT_EN_temp)begin    if(DATA_EN)   //.... up-> 0 and down->1    BIT_EN<=BIT_EN_temp;    else    BIT_EN<=0;end*/// aquaire signal statealways @(posedge BIT_EN_temp) //Signal_det) begin  last_flag <= current_flag;  if (Signal_A)    begin      current_flag <= A;     end  else if (Signal_B)    begin      current_flag <= B;     end  else     begin      current_flag <= C;      endend			assign full_flag = {last_flag,current_flag};// fsm design// next state of fsmassign next_state=fsm_function(full_flag);function[1:0] fsm_function;//【1：0】返回值的位寬    input[3:0] full_flag;    case(current_state)        idle:            begin                if(full_flag[1:0]==C)                 fsm_function=start;                else                fsm_function=idle;            end        start:            begin                if(full_flag=={C,A}||full_flag=={C,C})                fsm_function=data;                else                fsm_function=idle;            end        data:            begin                if(full_flag=={B,B}||full_flag=={C,B})                fsm_function=idle;                else                fsm_function=data;            end        default:fsm_function=idle;    endcaseendfunction// current state of fsmalways @(negedge BIT_EN_temp) //Signal_det)begin    if(!RESET)    current_state<=idle;    else    current_state<=next_state;end// output of fsmalways @(negedge BIT_EN_temp or negedge RESET)//full_flagbegin    if(!RESET)       begin            DATA_EN<=0;            DOUT<=0;           // BIT_EN<=0;            current_flag=B;       end    else begin         case(current_state)            idle:                begin                    DATA_EN<=0;                    DOUT<=0;                end            start:                /*                begin                    case(full_flag)                        {C,A}:begin DOUT<=1;DATA_EN<=1;end                        {C,C}:begin DOUT<=0;DATA_EN<=1;end                        default:begin DOUT<=0;DATA_EN<=0;end                    endcase                end*/                begin                    DATA_EN<=0;                    DOUT<=0;                end            data:                begin                    DATA_EN<=1;    		              case (full_flag) 		             // output the front data to avoid getting the stop_signal C errorly		                   {A,A}: DOUT<=1;		                   {A,B}: DOUT<=1;		                   {B,A}: DOUT<=0;					          {B,C}: DOUT<=0;					          {C,A}: DOUT<=0;					          {C,C}: DOUT<=0;					          default:    begin DATA_EN<=0;DOUT<=0;end				        endcase					    end				default:				    begin				        DATA_EN<=0;                DOUT<=0;                end		    endcase		    end  // end case beginend  // end block of output                    endmodule