写一个FFT的verilog实现代码

下面是一个基于蝴蝶算法的 8 点 FFT 的 Verilog 实现代码。

module fft8(
    input clk,
    input rst,
    input signed [15:0] x_re [8],
    input signed [15:0] x_im [8],
    output reg signed [15:0] y_re [8],
    output reg signed [15:0] y_im [8]
);

parameter FFT_STAGES = 3;

// Butterfly module
module butterfly(
    input signed [15:0] x_re,
    input signed [15:0] x_im,
    input signed [15:0] w_re,
    input signed [15:0] w_im,
    output reg signed [15:0] y_re,
    output reg signed [15:0] y_im
);

always @(*) begin
    y_re = x_re*w_re - x_im*w_im;
    y_im = x_re*w_im + x_im*w_re;
end

endmodule // butterfly

// Butterfly stage module
module butterfly_stage(
    input clk,
    input rst,
    input signed [15:0] x_re [8],
    input signed [15:0] x_im [8],
    output reg signed [15:0] y_re [8],
    output reg signed [15:0] y_im [8],
    input signed [15:0] w_re [4],
    input signed [15:0] w_im [4]
);

wire signed [15:0] b0_re [4];
wire signed [15:0] b0_im [4];
wire signed [15:0] b1_re [4];
wire signed [15:0] b1_im [4];
wire signed [15:0] b2_re [4];
wire signed [15:0] b2_im [4];
wire signed [15:0] b3_re [4];
wire signed [15:0] b3_im [4];

butterfly b0(clk, rst, x_re[0], x_im[0], w_re[0], w_im[0], b0_re[0], b0_im[0]);
butterfly b1(clk, rst, x_re[1], x_im[1], w_re[1], w_im[1], b1_re[0], b1_im[0]);
butterfly b2(clk, rst, x_re[2], x_im[2], w_re[2], w_im[2], b2_re[0], b2_im[0]);
butterfly b3(clk, rst, x_re[3], x_im[3], w_re[3], w_im[3], b3_re[0], b3_im[0]);

butterfly b4(clk, rst, x_re[4], x_im[4], w_re[0], w_im[0], b0_re[1], b0_im[1]);
butterfly b5(clk, rst, x_re[5], x_im[5], w_re[1], w_im[1], b1_re[1], b1_im[1]);
butterfly b6(clk, rst, x_re[6], x_im[6], w_re[2], w_im[2], b2_re[1], b2_im[1]);
butterfly b7(clk, rst, x_re[7], x_im[7], w_re[3], w_im[3], b3_re[1], b3_im[1]);

butterfly b8(clk, rst, b0_re[0], b0_im[0], w_re[0], w_im[0], y_re[0], y_im[0]);
butterfly b9(clk, rst, b1_re[0], b1_im[0], w_re[1], w_im[1], y_re[1], y_im[1]);
butterfly b10(clk, rst, b2_re[0], b2_im[0], w_re[2], w_im[2], y_re[2], y_im[2]);
butterfly b11(clk, rst, b3_re[0], b3_im[0], w_re[3], w_im[3], y_re[3], y_im[3]);

butterfly b12(clk, rst, b0_re[1], b0_im[1], w_re[0], w_im[0], y_re[4], y_im[4]);
butterfly b13(clk, rst, b1_re[1], b1_im[1], w_re[1], w_im[1], y_re[5], y_im[5]);
butterfly b14(clk, rst, b2_re[1], b2_im[1], w_re[2], w_im[2], y_re[6], y_im[6]);
butterfly b15(clk, rst, b3_re[1], b3_im[1], w_re[3], w_im[3], y_re[7], y_im[7]);

endmodule // butterfly_stage

// FFT module
module fft8(
    input clk,
    input rst,
    input signed [15:0] x_re [8],
    input signed [15:0] x_im [8],
    output reg signed [15:0] y_re [8],
    output reg signed [15:0] y_im [8]
);

wire signed [15:0] b0_re [8];
wire signed [15:0] b0_im [8];
wire signed [15:0] b1_re [8];
wire signed [15:0] b1_im [8];
wire signed [15:0] b2_re [8];
wire signed [15:0] b2_im [8];

// Twiddle factors
parameter signed [15:0] w_re [4] = {16'h7FFF, 16'h0000, 16'h7FFF, 16'h0000};
parameter signed [15:0] w_im [4] = {16'h0000, 16'h7FFF, 16'h0000, 16'h7FFF};

butterfly_stage bs0(clk, rst, x_re, x_im, b0_re, b0_im, w_re, w_im);
butterfly_stage bs1(clk, rst, b0_re, b0_im, b1_re, b1_im, w_re[2:3], w_im[2:3]);
butterfly_stage bs2(clk, rst, b1_re, b1_im, b2_re, b2_im, w_re[3:3], w_im[3:3]);

assign y_re = b2_re;
assign y_im = b2_im;

endmodule // fft8

此代码是一个简单的 FFT 实现，仅用于教学目的。实际应用中，需要考虑更复杂的场景和实现细节。