How To Calculate CPI And SPI In CSVTU

Hello Guys I am pursuing B.Tech from Chhattisgarh Swami Vivekanand Technical University (CSVTU) and I had written B.Tech (1st semester) Exam. Today I have got my Result as 77% marks. I have no idea how to calculate Cumulative Performance Index (CPI) and Semester Percentage Index (SPI). Would you please provide me a straight forward way to calculate CPI and SPI?