在EDA实验课上面，自己编写的NCO程序，可以产生出比较真实的正弦波、三角波以及锯齿波，用VHDL程序编写，有modelsim仿真textbench程序-On EDA experiment, oneself write the NCO program, can produce more real sine wave, triangular wave and sawtooth wave with VHDL programming, have the modelsim simulation text