CART RULE APPLIED ONLY TO SALE PRODUCTS

[gmclouddesign]

I need help to achieve something it will very useful to us.

I have a Prestashop 1.6 and I want to have a CART RULE wich applies ONLY to SALE PRODUCTS.

Here is an example:

Product 1 -> Regular price 10€

Product 2 -> Regular price 10€ -> Sale price 8€

Cart rule -> 10% for on sale products

Total products -> 18€

Cart rule -> 10% for the on sale product on cart 8€ * 10% = 0,8€

Shipping -> 4€

Total cart -> 18€ - 0,8€ + 4€ = 21,2€.

Is there any module you know that can achieve this? It would be very useful for having a campaing of EXTRA DISCOUNT ON SALE ITEMS.

Thanks!