sequential detector

This is used here “11010” Sequence detector as an example .

The sequence detector is to detect a specified sequence from the digital code stream , When a sequence appears at the input 11010 when , Output is 1, Otherwise, the output is 0. Repeat sequences are not considered here , That is, the sequence detection will be restarted after the specified sequence appears , No longer consider previous data .
The state transition diagram of the sequence detector is shown in the following figure ：

The code is as follows ：

module seqdet(D_out, D_in, rst_n, clk);
	parameter IDLE = 3'b0, A = 3'b1, B = 3'b2, C = 3'b3, D = 3'b4, E = 3'b5;
	output D_out;
	input D_in, rst_n, clk;
	reg[2:0]state, next_state;
	wire D_out;
		assign D_out = (state == E)?1:0;
		[email protected](state or D_in)
			case(state)
				IDLE:if(D_in)
						next_state = A;
					 else
					 	next_state = IDLE;
				A:if(D_in)
					next_state = B;
				  else
				  	next_state = IDLE;
				B:if(D_in)
					next_state = B;
				  else
				  	next_state = C;
				C:if(D_in)
					next_state = D;
				  else
				  	next_state = IDLE;
				D:if(D_in)
					next_state = B;
				  else
				  	next_state = E;
				E:if(D_in)
					next_state = IDLE;
				  else
				  	next_state = A;
				default: next_state = IDLE;
			endcase
		[email protected](posedge clk)
			state <= next_state;
endmodule

You can see , When they arrive in E In the state of ,11010 Sequence detection completed , meanwhile D_out Output 1. Next, if 1 Go to A The state continues with the next sequence of detection , If... Is detected 0 Then return to IDLE Status waiting .