手写Verilog FFT

Sure! Here's an example of a handwritten Verilog code for implementing a Radix-2 Decimation in Time (DIT) Fast Fourier Transform (FFT):

module fft (
  input wire clk,
  input wire reset,
  input wire [15:0] x_real,
  input wire [15:0] x_imag,
  output reg [15:0] X_real,
  output reg [15:0] X_imag
);

  reg [15:0] twiddle_real[7:0];
  reg [15:0] twiddle_imag[7:0];
  reg [15:0] stage_real[7:0];
  reg [15:0] stage_imag[7:0];
  
  always @(posedge clk or posedge reset) begin
    if (reset) begin
      for (i = 0; i < 8; i = i + 1) begin
        twiddle_real[i] <= 16'h0000;
        twiddle_imag[i] <= 16'h0000;
        stage_real[i] <= 16'h0000;
        stage_imag[i] <= 16'h0000;
      end
    end else begin
      // Twiddle factors calculation
      twiddle_real[0] <= 16'h7FFF; // Twiddle factor for stage 1
      twiddle_imag[0] <= 16'h0000;
      twiddle_real[1] <= 16'h5A82; // Twiddle factor for stage 2
      twiddle_imag[1] <= 16'h5A82;
      twiddle_real[2] <= 16'h0000; // Twiddle factor for stage 3
      twiddle_imag[2] <= 16'h7FFF;
      twiddle_real[3] <= -16'h5A82; // Twiddle factor for stage 4
      twiddle_imag[3] <= 16'h5A82;
      twiddle_real[4] <= -16'h7FFF; // Twiddle factor for stage 5
      twiddle_imag[4] <= 16'h0000;
      twiddle_real[5] <= -16'h5A82; // Twiddle factor for stage 6
      twiddle_imag[5] <= -16'h5A82;
      twiddle_real[6] <= 16'h0000; // Twiddle factor for stage 7
      twiddle_imag[6] <= -16'h7FFF;
      
      // Butterfly computation
      stage_real[0] <= x_real;
      stage_imag[0] <= x_imag;
      
      stage_real[1] <= (stage_real[0] + (stage_real[0] >> 8));
      stage_imag[1] <= (stage_imag[0] + (stage_imag[0] >> 8));
      
      stage_real[2] <= (stage_real[0] - (stage_real[0] >> 8));
      stage_imag[2] <= (stage_imag[0] - (stage_imag[0] >> 8));
      
      stage_real[3] <= (stage_real[1]*twiddle_real[0] - stage_imag[1]*twiddle_imag[0]) >> 15;
      stage_imag[3] <= (stage_real[1]*twiddle_imag[0] + stage_imag[1]*twiddle_real[0]) >> 15;
      
      stage_real[4] <= (stage_real[1]*twiddle_real[1] - stage_imag[1]*twiddle_imag[1]) >> 15;
      stage_imag[4] <= (stage_real[1]*twiddle_imag[1] + stage_imag[1]*twiddle_real[1]) >> 15;
      
      stage_real[5] <= (stage_real[2]*twiddle_real[2] - stage_imag[2]*twiddle_imag[2]) >> 15;
      stage_imag[5] <= (stage_real[2]*twiddle_imag[2] + stage_imag[2]*twiddle_real[2]) >> 15;
      
      stage_real[6] <= (stage_real[2]*twiddle_real[3] - stage_imag[2]*twiddle_imag[3]) >> 15;
      stage_imag[6] <= (stage_real[2]*twiddle_imag[3] + stage_imag[2]*twiddle_real[3]) >> 15;
      
      stage_real[7] <= (stage_real[3]*twiddle_real[4] - stage_imag[3]*twiddle_imag[4]) >> 15;
      stage_imag[7] <= (stage_real[3]*twiddle_imag[4] + stage_imag[3]*twiddle_real[4]) >> 15;
      
      X_real <= stage_real[7];
      X_imag <= stage_imag[7];
    end
  end
endmodule

This code represents an 8-point FFT implementation using fixed-point arithmetic. The input `x_real` and `x_imag` represent the real and imaginary parts of the input samples respectively. The output `X_real` and `X_imag` represent the real and imaginary parts of the FFT result.

Please note that this code is just a basic example, and you may need to modify it according to your specific requirements or design constraints.