filtering input text wiht jquery

i want to filtering and locking a input text . for example in some input when user type persian/farsi charachters cant type english or when user type english cant type persian.
means some input only accepet persian/farsi characters and some other accept english.
thanks.
also i find this http://www.thimbleopensource.com/tutorials-snippets/jquery-plugin-filter-text-input

if know any regular experssion for persian characters can help me.
or how can change the keyboard mode.

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