Altera官方的VHDL_Testbench教程,想学怎么写Testbench的话,强烈建议看一看。（英文的文档，不过都不难。耐心看完吧！）-Altera official VHDL_Testbench tutorial, want to learn how to write Testbench, then strongly recommended that a look. (English document, but are not difficult. The patience to re