verilog FFT
时间: 2023-06-14 21:06:20 浏览: 117
FFT(快速傅里叶变换)是一种高效的数字信号处理方法,通常在数字信号处理器(DSP)和数字信号的FPGA实现中使用。在FPGA中实现FFT可以提高处理速度和系统性能。Verilog是一种硬件描述语言,常用于FPGA的设计和实现。
以下是一个实现基于蝶形算法的8点FFT的Verilog代码示例:
```verilog
module fft8(
input [7:0] data_real_in,
input [7:0] data_imag_in,
output [7:0] data_real_out,
output [7:0] data_imag_out
);
reg [7:0] W_real[2:0][2:0];
reg [7:0] W_imag[2:0][2:0];
// 初始化旋转因子
initial begin
W_real[0][0] = 128; W_imag[0][0] = 0;
W_real[0][1] = -86; W_imag[0][1] = -86;
W_real[0][2] = 0; W_imag[0][2] = -128;
W_real[1][0] = 0; W_imag[1][0] = 0;
W_real[1][1] = -121; W_imag[1][1] = 121;
W_real[1][2] = 121; W_imag[1][2] = 121;
W_real[2][0] = 0; W_imag[2][0] = 0;
W_real[2][1] = -86; W_imag[2][1] = 86;
W_real[2][2] = 0; W_imag[2][2] = 128;
end
// 第一级蝶形运算
reg [7:0] t1_real, t1_imag, t2_real, t2_imag;
assign t1_real = data_real_in[0] + data_real_in[4];
assign t1_imag = data_imag_in[0] + data_imag_in[4];
assign t2_real = data_real_in[0] - data_real_in[4];
assign t2_imag = data_imag_in[0] - data_imag_in[4];
assign data_real_out[0] = t1_real + t2_real;
assign data_imag_out[0] = t1_imag + t2_imag;
assign data_real_out[4] = t1_real - t2_real;
assign data_imag_out[4] = t1_imag - t2_imag;
// 第二级蝶形运算
assign t1_real = data_real_in[1] + data_real_in[5];
assign t1_imag = data_imag_in[1] + data_imag_in[5];
assign t2_real = data_real_in[1] - data_real_in[5];
assign t2_imag = data_imag_in[1] - data_imag_in[5];
assign data_real_out[1] = t1_real + W_real[0][1]*t2_real - W_imag[0][1]*t2_imag;
assign data_imag_out[1] = t1_imag + W_real[0][1]*t2_imag + W_imag[0][1]*t2_real;
assign data_real_out[5] = t1_real - W_real[0][1]*t2_real + W_imag[0][1]*t2_imag;
assign data_imag_out[5] = t1_imag - W_real[0][1]*t2_imag - W_imag[0][1]*t2_real;
assign t1_real = data_real_in[2] + data_real_in[6];
assign t1_imag = data_imag_in[2] + data_imag_in[6];
assign t2_real = data_real_in[2] - data_real_in[6];
assign t2_imag = data_imag_in[2] - data_imag_in[6];
assign data_real_out[2] = t1_real + W_real[0][2]*t2_real - W_imag[0][2]*t2_imag;
assign data_imag_out[2] = t1_imag + W_real[0][2]*t2_imag + W_imag[0][2]*t2_real;
assign data_real_out[6] = t1_real - W_real[0][2]*t2_real + W_imag[0][2]*t2_imag;
assign data_imag_out[6] = t1_imag - W_real[0][2]*t2_imag - W_imag[0][2]*t2_real;
assign t1_real = data_real_in[3] + data_real_in[7];
assign t1_imag = data_imag_in[3] + data_imag_in[7];
assign t2_real = data_real_in[3] - data_real_in[7];
assign t2_imag = data_imag_in[3] - data_imag_in[7];
assign data_real_out[3] = t1_real + W_real[0][1]*t2_real - W_imag[0][1]*t2_imag;
assign data_imag_out[3] = t1_imag + W_real[0][1]*t2_imag + W_imag[0][1]*t2_real;
assign data_real_out[7] = t1_real - W_real[0][1]*t2_real + W_imag[0][1]*t2_imag;
assign data_imag_out[7] = t1_imag - W_real[0][1]*t2_imag - W_imag[0][1]*t2_real;
// 第三级蝶形运算
assign t1_real = data_real_out[0] + data_real_out[2];
assign t1_imag = data_imag_out[0] + data_imag_out[2];
assign t2_real = data_real_out[4] + data_real_out[6];
assign t2_imag = data_imag_out[4] + data_imag_out[6];
assign data_real_out[0] = t1_real + t2_real;
assign data_imag_out[0] = t1_imag + t2_imag;
assign data_real_out[4] = t1_real - t2_real;
assign data_imag_out[4] = t1_imag - t2_imag;
assign t1_real = data_real_out[1] + data_real_out[3];
assign t1_imag = data_imag_out[1] + data_imag_out[3];
assign t2_real = W_real[1][1]*data_real_out[5] - W_imag[1][1]*data_imag_out[5];
assign t2_imag = W_real[1][1]*data_imag_out[5] + W_imag[1][1]*data_real_out[5];
assign data_real_out[1] = t1_real + t2_real;
assign data_imag_out[1] = t1_imag + t2_imag;
assign data_real_out[5] = t1_real - t2_real;
assign data_imag_out[5] = t1_imag - t2_imag;
assign t1_real = data_real_out[2] - data_real_out[0];
assign t1_imag = data_imag_out[2] - data_imag_out[0];
assign t2_real = W_real[2][1]*data_real_out[6] - W_imag[2][1]*data_imag_out[6];
assign t2_imag = W_real[2][1]*data_imag_out[6] + W_imag[2][1]*data_real_out[6];
assign data_real_out[2] = t1_real + t2_imag;
assign data_imag_out[2] = t1_imag - t2_real;
assign data_real_out[6] = t1_real - t2_imag;
assign data_imag_out[6] = t1_imag + t2_real;
assign t1_real = data_real_out[3] - data_real_out[1];
assign t1_imag = data_imag_out[3] - data_imag_out[1];
assign t2_real = W_real[1][1]*data_real_out[7] - W_imag[1][1]*data_imag_out[7];
assign t2_imag = W_real[1][1]*data_imag_out[7] + W_imag[1][1]*data_real_out[7];
assign data_real_out[3] = t1_real + t2_imag;
assign data_imag_out[3] = t1_imag - t2_real;
assign data_real_out[7] = t1_real - t2_imag;
assign data_imag_out[7] = t1_imag + t2_real;
endmodule
```
该代码实现了一个8点FFT,并采用了蝶形算法。在代码中,使用了一个三维数组来存储旋转因子,通过初始化来实现。在每个蝶形运算中,使用了多次的加减乘除运算,通过assign语句赋值给输出信号。
需要注意的是,该代码只是一个简单的示例,实际的FFT实现可能需要更多的代码和优化,以满足实际应用的性能和精度要求。
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