用Verilog语言写一个FFT算法

以下是一个基于Verilog语言的8点FFT算法的示例代码：

module fft (
  input  clk, // 时钟信号
  input  rst, // 复位信号
  input  [7:0] x_r[0:7], // 输入实部数据
  input  [7:0] x_i[0:7], // 输入虚部数据
  output [7:0] y_r[0:7], // 输出实部数据
  output [7:0] y_i[0:7]  // 输出虚部数据
);

// 定义常量
localparam N = 8;        // FFT点数
localparam L = 3;        // FFT级数
localparam W = 8'b10110000; // 旋转因子（W8）

// 定义暂存器
reg [7:0] buffer_r[0:N-1], buffer_i[0:N-1];
reg [7:0] twiddle_r[0:N/2-1], twiddle_i[0:N/2-1];

// 定义内部信号
wire [7:0] butterfly_r[0:N-1], butterfly_i[0:N-1];
wire [7:0] adder_r[0:N-1], adder_i[0:N-1];

// 初始化旋转因子
initial begin
  twiddle_r[0] = 8'b11111111;
  twiddle_i[0] = 0;
  for (int i = 1; i < N/2; i = i*2) begin
    for (int j = 0; j < i; j++) begin
      twiddle_r[i+j] = twiddle_r[j];
      twiddle_i[i+j] = twiddle_i[j] ^ (1 << (L-1-j));
    end
  end
end

// 重新排列输入数据
assign buffer_r[0] = x_r[0];
assign buffer_i[0] = x_i[0];
assign buffer_r[1] = x_r[4];
assign buffer_i[1] = x_i[4];
assign buffer_r[2] = x_r[2];
assign buffer_i[2] = x_i[2];
assign buffer_r[3] = x_r[6];
assign buffer_i[3] = x_i[6];
assign buffer_r[4] = x_r[1];
assign buffer_i[4] = x_i[1];
assign buffer_r[5] = x_r[5];
assign buffer_i[5] = x_i[5];
assign buffer_r[6] = x_r[3];
assign buffer_i[6] = x_i[3];
assign buffer_r[7] = x_r[7];
assign buffer_i[7] = x_i[7];

// FFT计算
generate
  gen_butterfly: for (int k = 1; k <= L; k++) begin
    assign w_r = twiddle_r[(1<<(L-k))-1];
    assign w_i = twiddle_i[(1<<(L-k))-1];
    gen_group: for (int i = 0; i < N; i = i + (1<<k)) begin
      gen_stage: for (int j = 0; j < (1<<(k-1)); j++) begin
        assign a_r = buffer_r[i+j];
        assign a_i = buffer_i[i+j];
        assign b_r = buffer_r[i+j+(1<<(k-1))];
        assign b_i = buffer_i[i+j+(1<<(k-1))];
        assign t_r = w_r * b_r - w_i * b_i;
        assign t_i = w_r * b_i + w_i * b_r;
        assign c_r = a_r + t_r;
        assign c_i = a_i + t_i;
        assign d_r = a_r - t_r;
        assign d_i = a_i - t_i;
        assign butterfly_r[i+j] = c_r;
        assign butterfly_i[i+j] = c_i;
        assign butterfly_r[i+j+(1<<(k-1))] = d_r;
        assign butterfly_i[i+j+(1<<(k-1))] = d_i;
      end
    end
    assign buffer_r = butterfly_r;
    assign buffer_i = butterfly_i;
  end
endgenerate

// 输出结果
assign y_r[0] = buffer_r[0];
assign y_i[0] = buffer_i[0];
assign y_r[1] = buffer_r[4];
assign y_i[1] = buffer_i[4];
assign y_r[2] = buffer_r[2];
assign y_i[2] = buffer_i[2];
assign y_r[3] = buffer_r[6];
assign y_i[3] = buffer_i[6];
assign y_r[4] = buffer_r[1];
assign y_i[4] = buffer_i[1];
assign y_r[5] = buffer_r[5];
assign y_i[5] = buffer_i[5];
assign y_r[6] = buffer_r[3];
assign y_i[6] = buffer_i[3];
assign y_r[7] = buffer_r[7];
assign y_i[7] = buffer_i[7];

endmodule

该代码实现了一个基于蝴蝶算法的8点FFT，使用了Verilog语言描述，可以通过仿真和综合工具进行验证和实现。