PI controller in arduino

Using Arduino Programming Questions
1

Hello to all. First sorry for my poor English.
I have a question.
Actually I'm controlling speed of DC motor by arduino and I need to a PI controller like below picture.

How could I program a PI controller in arduino.Is there any library for it, if not, what can I do?
Very thank you.

2

leoncorleone:
How could I program a PI controller in arduino.Is there any library for it,

There's a PID Library, and I think PI is just PI with no D used.

3

Very thank you.