verilog实现64点fft

以下是一个基于 Verilog 的 64 点 FFT 的实现示例：

// 定义常量
`define N 6
`define M 64

module fft (
  input clk, // 时钟信号
  input rst, // 复位信号
  input signed [`N-1:0] x_r, // 输入实数部分
  input signed [`N-1:0] x_i, // 输入虚数部分
  output signed [`N-1:0] y_r, // 输出实数部分
  output signed [`N-1:0] y_i  // 输出虚数部分
);

  // 定义变量
  wire signed [`N-1:0] w_r [`M/2-1:0];
  wire signed [`N-1:0] w_i [`M/2-1:0];
  wire signed [`N-1:0] y_r_temp [`M/2-1:0];
  wire signed [`N-1:0] y_i_temp [`M/2-1:0];
  wire signed [`N-1:0] y_r_stage0 [`M/2-1:0];
  wire signed [`N-1:0] y_i_stage0 [`M/2-1:0];
  wire signed [`N-1:0] y_r_stage1 [`M/4-1:0];
  wire signed [`N-1:0] y_i_stage1 [`M/4-1:0];
  wire signed [`N-1:0] y_r_stage2 [`M/8-1:0];
  wire signed [`N-1:0] y_i_stage2 [`M/8-1:0];
  wire signed [`N-1:0] y_r_stage3 [`M/16-1:0];
  wire signed [`N-1:0] y_i_stage3 [`M/16-1:0];
  wire signed [`N-1:0] y_r_stage4 [`M/32-1:0];
  wire signed [`N-1:0] y_i_stage4 [`M/32-1:0];
  wire signed [`N-1:0] y_r_stage5 [`M/64-1:0];
  wire signed [`N-1:0] y_i_stage5 [`M/64-1:0];

  // 生成旋转因子
  generate
    genvar i;
    for (i = 0; i < `M/2; i = i + 1) begin
      assign w_r[i] = cos(2 * $PI * i / `M);
      assign w_i[i] = -sin(2 * $PI * i / `M);
    end
  endgenerate

  // 第一级蝴蝶运算
  assign y_r_stage0[0] = x_r + x_r;
  assign y_i_stage0[0] = x_i + x_i;
  assign y_r_stage0[1] = x_r - x_r;
  assign y_i_stage0[1] = x_i - x_i;
  assign y_r_stage0[2] = x_r + x_i;
  assign y_i_stage0[2] = x_i - x_r;
  assign y_r_stage0[3] = x_r - x_i;
  assign y_i_stage0[3] = x_i + x_r;

  // 第二级蝴蝶运算
  assign y_r_stage1[0] = y_r_stage0[0] + y_r_stage0[2];
  assign y_i_stage1[0] = y_i_stage0[0] + y_i_stage0[2];
  assign y_r_stage1[1] = y_r_stage0[1] + y_r_stage0[3];
  assign y_i_stage1[1] = y_i_stage0[1] + y_i_stage0[3];
  assign y_r_stage1[2] = y_r_stage0[0] - y_r_stage0[2];
  assign y_i_stage1[2] = y_i_stage0[0] - y_i_stage0[2];
  assign y_r_stage1[3] = y_r_stage0[1] - y_r_stage0[3];
  assign y_i_stage1[3] = y_i_stage0[1] - y_i_stage0[3];

  // 第三级蝴蝶运算
  assign y_r_stage2[0] = y_r_stage1[0] + y_r_stage1[1];
  assign y_i_stage2[0] = y_i_stage1[0] + y_i_stage1[1];
  assign y_r_stage2[1] = y_r_stage1[0] - y_r_stage1[1];
  assign y_i_stage2[1] = y_i_stage1[0] - y_i_stage1[1];
  assign y_r_stage2[2] = y_r_stage1[2] + y_r_stage1[3];
  assign y_i_stage2[2] = y_i_stage1[2] + y_i_stage1[3];
  assign y_r_stage2[3] = (y_r_stage1[2] - y_r_stage1[3]) * w_r[0] - (y_i_stage1[2] - y_i_stage1[3]) * w_i[0];
  assign y_i_stage2[3] = (y_r_stage1[2] - y_r_stage1[3]) * w_i[0] + (y_i_stage1[2] - y_i_stage1[3]) * w_r[0];

  // 第四级蝴蝶运算
  assign y_r_stage3[0] = y_r_stage2[0] + y_r_stage2[2];
  assign y_i_stage3[0] = y_i_stage2[0] + y_i_stage2[2];
  assign y_r_stage3[1] = y_r_stage2[1] + y_r_stage2[3];
  assign y_i_stage3[1] = y_i_stage2[1] + y_i_stage2[3];
  assign y_r_stage3[2] = y_r_stage2[0] - y_r_stage2[2];
  assign y_i_stage3[2] = y_i_stage2[0] - y_i_stage2[2];
  assign y_r_stage3[3] = (y_r_stage2[1] - y_r_stage2[3]) * w_r[1] - (y_i_stage2[1] - y_i_stage2[3]) * w_i[1];
  assign y_i_stage3[3] = (y_r_stage2[1] - y_r_stage2[3]) * w_i[1] + (y_i_stage2[1] - y_i_stage2[3]) * w_r[1];

  // 第五级蝴蝶运算
  assign y_r_stage4[0] = y_r_stage3[0] + y_r_stage3[1];
  assign y_i_stage4[0] = y_i_stage3[0] + y_i_stage3[1];
  assign y_r_stage4[1] = y_r_stage3[0] - y_r_stage3[1];
  assign y_i_stage4[1] = y_i_stage3[0] - y_i_stage3[1];
  assign y_r_stage4[2] = y_r_stage3[2] + y_r_stage3[3];
  assign y_i_stage4[2] = y_i_stage3[2] + y_i_stage3[3];
  assign y_r_stage4[3] = (y_r_stage3[2] - y_r_stage3[3]) * w_r[2] - (y_i_stage3[2] - y_i_stage3[3]) * w_i[2];
  assign y_i_stage4[3] = (y_r_stage3[2] - y_r_stage3[3]) * w_i[2] + (y_i_stage3[2] - y_i_stage3[3]) * w_r[2];

  // 第六级蝴蝶运算
  assign y_r_stage5[0] = y_r_stage4[0] + y_r_stage4[2];
  assign y_i_stage5[0] = y_i_stage4[0] + y_i_stage4[2];
  assign y_r_stage5[1] = y_r_stage4[1] + y_r_stage4[3];
  assign y_i_stage5[1] = y_i_stage4[1] + y_i_stage4[3];
  assign y_r_stage5[2] = y_r_stage4[0] - y_r_stage4[2];
  assign y_i_stage5[2] = y_i_stage4[0] - y_i_stage4[2];
  assign y_r_stage5[3] = y_r_stage4[1] - y_r_stage4[3];
  assign y_i_stage5[3] = y_i_stage4[1] - y_i_stage4[3];

  // 输出结果
  assign y_r = y_r_stage5[0];
  assign y_i = y_i_stage5[0];

endmodule

这个代码实现了一个基于蝴蝶算法的 64 点 FFT。其中，旋转因子的计算使用了 verilog 内置的 `cos` 和 `sin` 函数。这个代码可能需要一些优化，以适应更高的频率和更复杂的输入数据。