fft verilog代码

以下是一个简单的FFT Verilog代码：

module FFT (
input clk,
input rst,
input [7:0] in_real,
input [7:0] in_imag,
output [7:0] out_real,
output [7:0] out_imag
);

// Define constants
parameter N = 8;
parameter logN = 3;

// Define internal signals
reg [7:0] data_real [0:N-1];
reg [7:0] data_imag [0:N-1];
reg [logN-1:0] stage;
reg [logN-1:0] i;
reg [logN-1:0] j;
reg [logN-1:0] k;
reg [logN-1:0] step;
reg [7:0] twiddle_real;
reg [7:0] twiddle_imag;
reg [7:0] temp_real;
reg [7:0] temp_imag;

// Initialize data
initial begin
for (i = 0; i < N; i = i + 1) begin
data_real[i] = in_real;
data_imag[i] = in_imag;
end
end

// Main FFT loop
always @(posedge clk) begin
if (rst) begin
stage <= 0;
i <= 0;
j <= 0;
k <= 0;
step <= 1;
out_real <= 0;
out_imag <= 0;
end else begin
// Calculate twiddle factor
twiddle_real = $cos(2*3.1415926*k/N);
twiddle_imag = -$sin(2*3.1415926*k/N);

// Perform butterfly operation
temp_real = data_real[j] + (twiddle_real * data_real[j+step]) - (twiddle_imag * data_imag[j+step]);
temp_imag = data_imag[j] + (twiddle_real * data_imag[j+step]) + (twiddle_imag * data_real[j+step]);
data_real[j+step] = data_real[j] - (twiddle_real * data_real[j+step]) + (twiddle_imag * data_imag[j+step]);
data_imag[j+step] = data_imag[j] - (twiddle_real * data_imag[j+step]) - (twiddle_imag * data_real[j+step]);
data_real[j] = temp_real;
data_imag[j] = temp_imag;

// Increment loop variables
k = k + 1;
if (k == N/step) begin
k <= 0;
j = j + step;
if (j == N-1) begin
j <= 0;
step = step * 2;
if (step == N) begin
// Copy data to output
out_real <= data_real;
out_imag <= data_imag;
// Reset variables for next FFT operation
stage <= 0;
i <= 0;
j <= 0;
k <= 0;
step <= 1;
end
end
end else begin
// Continue with same loop variables
// (i.e. repeat butterfly operation)
end
end
end

endmodule