Firmware Interview Questions

 He asked a puzzle that you have 500 switches and all are OFF. Now someone came and make all of them ON. Now a second person came and flip all the second switch and then 3rd came and flip all the 3rd switch and so on till 500. So tell me how many switch will be on after completing the entire process.


synchronization mechanisms for threads
associating a mutex with a condition variable solved it

mutex reursive
binary semaphore and mutex


Clone a linked list into two different linked lists such that one list contains the first half of the existing linked list, in the same order, and the other list contains the other half. Time complexity should be minimum.

How would you represent a sparse matrix using minimum space complexity such that all elements can be accessed through their row and column indices?


Prepare a STAR matrix
parse matrix.
C programming to the depth. like triple pointers, linked lists, algorithms etc.



1st F2F was on checking the logical ability and problem solving along with few C programming questions.

2nd F2F was on checking your knowledge on C programming to the depth. like triple pointers, linked lists, algorithms etc.

3rd F2F was on checking your domain knowledge required for the position

C Program to solve a puzzle.

Binary search algorithm and worst time complexity

what is the phase relationship between clock and data?

Low level binary, hex, bit shifting type questions.

Had multiple choice questions involving bit manipulation, and two hackerrank coding questions that both were heavy on string parsing.


What is a Hashtable and what is it used for?


Write a code for deciding if a number is power of two?

Write code to reverse a string.

What is hash table? What is it used for?

Increment vs decrement operator in a loop. which one is better? (https://stackoverflow.com/questions/8968785/which-loop-has-better-performance-increment-or-decrement)

Find the median of an array of elements, which can be changed dynamically, that is a new element is added. In this followup questions are a) What datatype will be used for this kind of structure. b) How to sort this array

Can a same interrupt handler be assigned to multiple interrupts? Can Malloc, printf statements be called from ISR?

Functions vs Inline Functions vs Macros

What are hardware and software breakpoints, how to use them

How does a cherry pick works in git


What is a reentrant function? (https://www.geeksforgeeks.org/reentrant-function/) (https://www.tutorialspoint.com/what-is-a-reentrant-function-in-c-cplusplus)

Deep copy vs Shallow Copy

Implement a function for n! using c++

Can we increment a void pointer. Size of void pointer

Some useless puzzle problems

c,data structures

The first interview was an in-depth discussion about synchronization mechanisms for threads. In particular, we discussed two problems: (i) the lost wakeup problem and how associating a mutex with a condition variable solved it. (ii) the thundering herd problem.

C programming puzzles.

Given an unsorted array find index i such that sum of i and i+1 is max.

Find maximum frequency word in a paragraph.

What is overloading/ overriding

given an array of 2 digit integers. Find the common digit between consecutive integers.


make stack using queue's and make queue using stack's

Structure Padding
Union
Structure vs uion
What is an enum, union and struct?

General bit manipulation questions.

Find the set bits in a number.
Find the number is power or 2 or not.

Difference between public and private variable
Write a function that multiples to integers without using the multiplication symbol

Shortest path algorithm between 5 nodes

Finite state machines Data structures, search methods, arrays, etc

C language based programming questions for which we need to write the output.


What is an emulator?

How do you return multiple variables?

Describe projects listed on resume and challenges / stuff you learned from them.


What does static mean in C?
What are the differences between C++ and C? (https://en.wikipedia.org/wiki/Compatibility_of_C_and_C%2B%2B)

How do you find the missing number in a set of 1 to 100?
What sorting method is the best option for the given situation?

merge sorted list, duplicate elements find.

full array is sorted just some small portion is not sorted
The first technical interview focused on problems about linked lists and bit manipulations.

The second technical interview focused on optimising the storage representation of a sparse matrix.


2 CPUs, 2 Devices, connected by a bus. Write a function to deliver cpu message to correct device





Question regarding RAM memory
Difference between the utility of graphs and tress




Function Overloading,Overriding, virtual functions, polymorphism,inheritance,truncate, joins, drop,delete from SQL. Questions from my projects were asked. Call by reference. call by value Java and C++(pointer and no pointer thing) PS: I forgot the remaining.


print File.read() twice, what is the second string displayed

What are the voltage levels of RS232
What is the Nyquist frequency?


You are given read-only access to all the modifying I/Os that target a block device, as they happen. Use this to implement point-in-time snapshots for the block device. The snapshots do not live on the block device. You are not allowed to modify the contents of the block device. Assume you are in user space. Feel free to assume access to anything else that you might need for your implementation; please do call your assumptions explicitly.