How to add VIM * functionality in EMACS VIPER mode?

[Weihua JIANG]

In normal mode of VIM, there is a very good functionality: when cursor
under any position of a word, you can press key "*" to use the whole
word under cursor (including both the chars before the cursor and after
it) as search pattern.

Now I switched to EMACS with VIPER mode. But VIPER lacks such
functionality. Can any one tell me how to implement it in VIPER with
some elisp code?

Thanks
Weihua Jiang