Verilog的QPSK解调器，输入下变频的IQ两路信号，通过costas环和Gardner环，输出控制nco的频率控制字和原基带信号的代码

以下是一个简单的Verilog实现，其中包含QPSK解调器、Costas环和Gardner环：

module qpsk_demodulator (
    input clk,
    input rst,
    input [7:0] i_in,
    input [7:0] q_in,
    output reg [7:0] data_out,
    output reg [7:0] freq_out
);

// 定义常量
parameter PI = 3.1415926;
parameter FREQ_STEP = 1;
parameter GAIN = 4;

// 定义寄存器
reg [7:0] i_last;
reg [7:0] q_last;
reg [7:0] i_diff;
reg [7:0] q_diff;
reg [7:0] i_corr;
reg [7:0] q_corr;
reg [7:0] i_demod;
reg [7:0] q_demod;
reg [7:0] freq_acc;
reg [1:0] phase_acc;
reg [1:0] phase_err;
reg [7:0] freq_err;
reg [7:0] freq_ctrl;
reg [7:0] data_reg;
reg [7:0] sample_reg;

// 初始化
initial begin
    i_last = 0;
    q_last = 0;
    i_diff = 0;
    q_diff = 0;
    i_corr = 0;
    q_corr = 0;
    i_demod = 0;
    q_demod = 0;
    freq_acc = 0;
    phase_acc = 0;
    phase_err = 0;
    freq_err = 0;
    freq_ctrl = 0;
    data_reg = 0;
    sample_reg = 0;
end

// Costas环
always @(posedge clk, posedge rst) begin
    if (rst) begin
        phase_acc <= 0;
        phase_err <= 0;
    end else begin
        i_diff <= i_in - i_last;
        q_diff <= q_in - q_last;
        i_corr <= i_diff * q_demod;
        q_corr <= q_diff * i_demod;
        phase_err <= i_corr - q_corr;
        phase_acc <= phase_acc + phase_err;
    end
end

// Gardner环
always @(posedge clk, posedge rst) begin
    if (rst) begin
        freq_ctrl <= 0;
        freq_err <= 0;
        freq_acc <= 0;
    end else begin
        freq_err <= phase_err * GAIN;
        freq_ctrl <= freq_ctrl + freq_err;
        freq_acc <= freq_acc + freq_ctrl;
    end
end

// NCO控制
always @(posedge clk, posedge rst) begin
    if (rst) begin
        freq_out <= 0;
    end else begin
        freq_out <= freq_acc;
    end
end

// QPSK解调
always @(posedge clk, posedge rst) begin
    if (rst) begin
        data_out <= 0;
        i_demod <= 0;
        q_demod <= 0;
    end else begin
        // 计算相位
        phase_acc <= phase_acc + freq_acc;
        phase_acc <= phase_acc % (2 * PI);

        // 计算解调信号
        i_demod <= i_in * $cos(phase_acc) - q_in * $sin(phase_acc);
        q_demod <= q_in * $cos(phase_acc) + i_in * $sin(phase_acc);

        // 采样和决策
        sample_reg <= sample_reg + 1;
        if (sample_reg == 4) begin
            sample_reg <= 0;
            data_reg <= {i_demod[7], q_demod[7]};
            data_out <= data_reg;
        end

        // 保存上一个样本
        i_last <= i_in;
        q_last <= q_in;
    end
end

endmodule

该实现包含一个QPSK解调器，它接收输入下变频的IQ信号，并通过Costas环和Gardner环来解调信号并控制NCO的频率。输出包括控制NCO的频率控制字和原始基带信号的代码。