lfsr.v

《数字信号处理的FPGA实现》代码

//*********************************************************
// IEEE STD 1364-1995 Verilog file: lfsr.v
// Author-EMAIL: [e-mail]
//*********************************************************
module lfsr (clk, y); //----> Interface

  input          clk;
  output [6:1]  y;  // Result

  reg [6:1] ff; // Note that reg is keyword in Verilog and 
                               // can not be variable name
  integer i;
        
  always @(posedge clk) begin // Length 6 LFSR with xnor
    ff[1] <= ff[5] ~^ ff[6]; // Use non-blocking assignment
    for (i=6; i>=2 ; i=i-1)  // Tapped delay line: shift one 
      ff[i] <= ff[i-1];
  end

  assign   y = ff;         // Connect to I/O cell

endmodule