verilog写出FFT算法

FFT（快速傅里叶变换）是一种高效的算法，它可以将离散时间信号转换为频域信号。在Verilog中，可以使用Butterfly模块来实现FFT算法。以下是一个基于蝴蝶操作的8点FFT的Verilog代码示例：

module fft_8_point(
  input clk,
  input rst,
  input [7:0] data_in_r,
  input [7:0] data_in_i,
  output [7:0] data_out_r,
  output [7:0] data_out_i
);

  //定义常量
  parameter N = 8;
  parameter M = $clog2(N);

  //定义临时变量
  reg [7:0] x_r[N];
  reg [7:0] x_i[N];
  reg [7:0] y_r[N];
  reg [7:0] y_i[N];

  //定义蝴蝶操作模块
  module butterfly(
    input clk,
    input [7:0] x_r,
    input [7:0] x_i,
    input [7:0] w_r,
    input [7:0] w_i,
    output [7:0] y_r,
    output [7:0] y_i
  );

    //定义临时变量
    reg [7:0] t1_r;
    reg [7:0] t1_i;
    reg [7:0] t2_r;
    reg [7:0] t2_i;

    //计算蝴蝶操作
    assign t1_r = x_r + w_r;
    assign t1_i = x_i + w_i;
    assign t2_r = x_r - w_r;
    assign t2_i = x_i - w_i;

    //输出结果
    assign y_r = t1_r;
    assign y_i = t1_i;

  endmodule

  //定义蝴蝶操作模块的实例
  butterfly butterfly0(
    .clk(clk),
    .x_r(x_r[0]),
    .x_i(x_i[0]),
    .w_r(0),
    .w_i(0),
    .y_r(y_r[0]),
    .y_i(y_i[0])
  );

  butterfly butterfly1(
    .clk(clk),
    .x_r(x_r[1]),
    .x_i(x_i[1]),
    .w_r(-128),
    .w_i(0),
    .y_r(y_r[1]),
    .y_i(y_i[1])
  );

  butterfly butterfly2(
    .clk(clk),
    .x_r(x_r[2]),
    .x_i(x_i[2]),
    .w_r(0),
    .w_i(-128),
    .y_r(y_r[2]),
    .y_i(y_i[2])
  );

  butterfly butterfly3(
    .clk(clk),
    .x_r(x_r[3]),
    .x_i(x_i[3]),
    .w_r(114),
    .w_i(-114),
    .y_r(y_r[3]),
    .y_i(y_i[3])
  );

  butterfly butterfly4(
    .clk(clk),
    .x_r(x_r[4]),
    .x_i(x_i[4]),
    .w_r(0),
    .w_i(0),
    .y_r(y_r[4]),
    .y_i(y_i[4])
  );

  butterfly butterfly5(
    .clk(clk),
    .x_r(x_r[5]),
    .x_i(x_i[5]),
    .w_r(-114),
    .w_i(114),
    .y_r(y_r[5]),
    .y_i(y_i[5])
  );

  butterfly butterfly6(
    .clk(clk),
    .x_r(x_r[6]),
    .x_i(x_i[6]),
    .w_r(0),
    .w_i(128),
    .y_r(y_r[6]),
    .y_i(y_i[6])
  );

  butterfly butterfly7(
    .clk(clk),
    .x_r(x_r[7]),
    .x_i(x_i[7]),
    .w_r(114),
    .w_i(114),
    .y_r(y_r[7]),
    .y_i(y_i[7])
  );

  //主计算过程
  always @(posedge clk) begin

    //重排输入序列
    for (i = 0; i < N; i = i + 1) begin
      x_r[i] <= data_in_r[bitrevorder(i)];
      x_i[i] <= data_in_i[bitrevorder(i)];
    end

    //执行M级蝴蝶操作
    for (m = 0; m < M; m = m + 1) begin
      n = 2**m;
      k = 2**(M-m-1);
      for (i = 0; i < N/(2*n); i = i + 1) begin
        for (j = 0; j < n; j = j + 1) begin
          butterfly #(8) bf(
            .clk(clk),
            .x_r(x_r[i*n+j]),
            .x_i(x_i[i*n+j]),
            .w_r(cos(j*k)),
            .w_i(-sin(j*k)),
            .y_r(y_r[i*n+j]),
            .y_i(y_i[i*n+j])
          );
        end
      end
      for (i = 0; i < N; i = i + 1) begin
        x_r[i] <= y_r[i];
        x_i[i] <= y_i[i];
      end
    end

    //输出结果
    for (i = 0; i < N; i = i + 1) begin
      data_out_r[bitrevorder(i)] <= y_r[i];
      data_out_i[bitrevorder(i)] <= y_i[i];
    end

  end

endmodule

这段代码实现了一个8点FFT算法，使用了8个Butterfly模块来进行计算。在主计算过程中，先将输入序列进行重排，然后执行M级蝴蝶操作。最后输出结果。