Qualcomm SW Engineer interview questions

1st Round was an Online Assesment, where 1st section was of Aptitude(20 Q's), 2nd section was of Maths(20Q's) and 3rd section was of programming(20Q's) which involved Basic DSA, C/C++ low level design questions. 2nd, 3rd and 4th were Interview rounds, where in 1st round of interview, the interviewer asked 10-12 Operating systems questions and one Simple DSA question. Second round was also a technical involving low level C/C++ questions and OOPS and then 3rd was HR round.