题解 | #不重叠序列检测#

`timescale 1ns/1ns
module sequence_detect(
	input clk,
	input rst_n,
	input data,
	output reg match,
	output reg not_match
	);

// 011100
//S = {a,num} = {a,3'b1} = {,3'b}
parameter  S1= {1'b0,3'b1};

parameter  S2= {1'b1,3'b010};
parameter  S3= {1'b1,3'b011};
parameter  S4= {1'b1,3'b100};
parameter  S5= {1'b0,3'b101};
parameter  S6= {1'b0,3'b110};
parameter  S0= {4'b0000};
reg [3:0] data_ray;
reg [2:0] data_num;
reg [3:0] st_now,st_next;
always@(posedge clk or negedge rst_n)
    if (~rst_n) begin
        data_ray = 0;
        data_num = 1;
    end
    else begin
        if (data_num == 7) begin
            data_num = 1;
        end
        data_ray = {data,data_num};
        data_num = data_num + 1;
    end

always @(posedge clk or negedge rst_n) begin
    if (~rst_n) begin
        st_now <= S0;
    end
    else
        st_now <= st_next;
end
always @(*) begin
    case(st_now)
        S0: st_next = (data_ray==S1)?S1:S0;
        S1: st_next = (data_ray==S2)?S2:S0;
        S2: st_next = (data_ray==S3)?S3:S0;
        S3: st_next = (data_ray==S4)?S4:S0;
        S4: st_next = (data_ray==S5)?S5:S0;
        S5: st_next = (data_ray==S6)?S6:S0;
        S6: st_next = (data_ray==S1)?S1:S0;
    endcase
end
always @(*) begin
    if (~rst_n) begin
        match = 0;
        not_match = 0;
    end
    else begin
        if (st_next==S6) begin
            match = 1;
        end
        else
            match = 0;
    
        if (data_num==7 && st_next==S0)
            not_match = 1;
        else
            not_match = 0;
    end
end
endmodule

match时序要比题目1个时钟周期提前才行。