Yes , you can still get admission in Sastra university if even you have not given JEE MAINS .You need to fill the application form under stream 2 until June 9,2018 and then ,you can get admission on the basis of your marks obtained in university qualifying exam . For more details about admission in Sastra university , follow the given link: https://engineering.careers360.com/articles/sastra-university-btech-admissions

Hope it helps!