Cognizant — I did not receive offer letter

I had interviewed on 15th dec'18 and got selected in cognizant. Hr told me that i will be getting offer. Now almost 40 days over till now i did not receive offer letter from hr. But i will be getting cal asking that am i willing to join or not. Actually i am interested and serving the notice period of two weeks. Please let me status of my offer. Fki [protected]@gmail.com