vga

代码说明：

说明：  实现在屏幕上显示绿色和红色相间的水平条纹。其中，vga_640x480模块将产生行同步信号hsyn和场同步信号 vsync; vga_stripes模块将产生red、green和blue三个输出。(The horizontal stripes of green and red are displayed on the screen. Among them, vga_640x480 module will produce line synchronization signal Hsyn and field synchronization signal vsync; vga_stripes module will produce red, green and blue three outputs.)