Qualcomm DSP Firmware Engineer interview questions

Telephonic Interview (30 minutes) He asked questions on everything that is there in my resume. First interviewer (one and half hour) He started with my M.Tech project. Then he concentrated on channel coding part. He asked C programs. If we transmit a bit stream, and if it gets corrupted and results in some errors ,then write a c program to find which bit stream was transmitted, if you have the original and corrupted signal. Second Interviewer(one hour) He asked some basic question on Signal Processing. He asked a basic question on conditional operator. Third Interviewer(30 minutes) He asked me about channel coding,source coding and about FIR and IIR filters. I asked him a question at the end. He did not listen my question properly and asked me who taught you Digital Communication. Fourth Interviewer(one and half hour) He is really nice. He asked me about my B.Tech project. He asked me about compiler design. He asked me about receiver types, example for orthonormal basis function. He asked me a basic reasoning question. I don't remember the question. Among all he is really supportive. Fifth Interviewer( one and half hour) By this time i was fully tired. He asked me what i know. Then he asked me question about Source coding, channel coding, modulation techniques, interleaver, Cyclic Redundancy check. He asked me what is the use of "Static". C program to find a given number in an array. I was fully exhausted and could not concentrate properly. Overall It was good. They did not give me any feedback for two months. I emailed them twice, then they replied that feedback was negative.