牛客进阶题目20：根据状态转移写状态机-二段式

把输出段与次态段合并即可

`timescale 1ns/1ns

module fsm2(
	input wire clk  ,
	input wire rst  ,
	input wire data ,
	output reg flag
);

//*************code***********//
localparam	S0 = 3'b000	;
localparam	S1 = 3'b001	;
localparam	S2 = 3'b010	;
localparam	S3 = 3'b011	;
localparam  S4 = 3'b100 ;

reg [2:0]	state,nxt_state	;

always @(posedge clk or negedge rst) begin
	if(!rst)
		state <= S0 ;
	else
		state <= nxt_state ;
end

always @(*) begin
	case(state) 
		S0 : begin	nxt_state = data ? S1 : S0 ; flag = 1'b0 ;	end
		S1 : begin	nxt_state = data ? S2 : S1 ; flag = 1'b0 ;	end
		S2 : begin	nxt_state = data ? S3 : S2 ; flag = 1'b0 ;	end
		S3 : begin	nxt_state = data ? S4 : S3 ; flag = 1'b0 ;	end
		S4 : begin	nxt_state = data ? S1 : S0 ; flag = 1'b1 ;	end
		default :  begin nxt_state = 3'b000 ; flag = 1'b0 ; end
	endcase
end
//*************code***********//
endmodule