请问这句话怎么理解？

tatata

我在看一个Xilinx的PDF文档时，遇到了下面这句话：
For HDL,these design elements are inferred rather than instantiated.

这句话是在ISE元件库（加法器）使用说明最后出现的。
请问该怎么理解这句话看呢？谢谢

magicball

This is an example for adder:

infer:  c = a + b;       => Tool will build an adder module
instantiate:   adder (.in1 (a), .in2 (b), .sum (c));  => Designer create the add module by himself.

vvvtmc

Seems that instantiate means less freedom of the synthesis tool, as it must follow what's declared?

zzczx

二楼的说得很对。 是推导出来的而不是你手工例化的