说明：  最近用Mega128写了一个128点FFT程序，浮点运算，加汉宁窗。由于窗函数和旋转因子通过查表得到，所以速度还可以，程序中给的初值是通过高速AD采集的20KHz正弦信号。计算结果与Matlab的FFT函数得到的结果相同。
(Mega128 recently wrote a 128-point FFT procedures, floating-point operations, Hanning window. Since the window function and the twiddle factor look-up table has been adopted, so the speed can also be, the initial value to the process through high-speed AD collected 20KHz sinusoidal signal. The calculation results with the Matlab)