题解 | #输入序列连续的序列检测#
输入序列连续的序列检测
http://www.nowcoder.com/practice/d65c2204fae944d2a6d9a3b32aa37b39
`timescale 1ns/1ns module sequence_detect( input clk, input rst_n, input a, output reg match ); localparam idle =9'b000000000; localparam s1 =9'b000000001; localparam s2 = 9'b000000010; localparam s3 = 9'b000000100; localparam s4 = 9'b000001000;
localparam s5 = 9'b000100000;
localparam s6 = 9'b001000000;
localparam s7 = 9'b010000000;
localparam s8 = 9'b100000000;
reg [8:0] cs,ns;
always@(posedge clk or negedge rst_n) begin
if(!rst_n)
cs <= 8'b0;
else cs <= ns;
end
always@(*) begin
case(cs)
idle:begin
if(a==0) ns = s1;
else ns = idle;
end
s1:begin
if(a==0) ns = s1;
else ns = s2;
end
s2:begin
if(a==0) ns = s1;
else ns = s3;
end
s3:begin
if(a==0) ns = s1;
else ns = s4;
end
s4:begin
if(a==0) ns = s5;
else ns = idle;
end
s5:begin
if(a==0) ns = s6;
else ns = s2;
end
s6:begin
if(a==0) ns = s7;
else ns = s2;
end
s7:begin
if(a==0) ns = s1;
else ns = s8;
end
s8:begin
if(a==0) ns = s1;
else ns = s3;
end
default: ns = idle;
endcase
end
always@(posedge clk or negedge rst_n) begin
if(!rst_n)
match <= 0;
else if(cs == s8) match <= 1;
else match <= 0;
end
endmodule
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