Qualcomm Interview Questions, Process, and Tips

Q1. Detect endianness using C program
Ans. 
Detect endianness using C program
• Use a union to create a variable with a known value

• Check the value of the first byte to determine endianness

• Big endian systems store the most significant byte first

• Little endian systems store the least significant byte first

• Example: union { int i; char c; } u; u.i = 1; if (u.c == 1) { /* Little endian */ } else { /* Big endian */ }
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Q2. Count set bits using C
Ans. 
Count set bits in a number using C programming language.
• Use bitwise AND operation with 1 to check if the rightmost bit is set.

• Shift the number to the right by 1 bit each time to check all bits.

• Repeat the process until the number becomes 0, counting the set bits each time.
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Q1. Mostly on C, OS and wireless comm fundamentals.
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Q2. What does malloc return?
Ans. 
malloc returns a pointer to a block of memory allocated from the heap.
• malloc returns a void pointer (void*)

• The returned pointer can be cast to the desired data type

• If malloc fails to allocate memory, it returns NULL
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Q3. What is RTOS and how does it differ from OS?
Ans. 
RTOS stands for Real-Time Operating System. It is designed to handle time-sensitive tasks and provide deterministic behavior.
• RTOS is optimized for real-time applications that require precise timing and responsiveness.

• Unlike general-purpose operating systems, RTOS provides deterministic behavior, meaning tasks are guaranteed to be completed within a specific time frame.

• RTOS typically uses priority-based scheduling algor...read more
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Q4. Why not to use malloc?
Ans. 
malloc should be avoided due to potential memory leaks and security vulnerabilities.
• malloc does not initialize memory, leading to potential bugs and crashes.

• It does not provide any bounds checking, leading to buffer overflows.

• Memory allocated with malloc must be explicitly freed with free() to avoid memory leaks.

• Using malloc can be less efficient than using stack memory for small allocations.

• Alternatives like calloc() ...read more
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Q5. What happens at stack/memory level when a null ptr is dereferenced?
Ans. 
When a null pointer is dereferenced, it leads to a segmentation fault or access violation, causing the program to crash.
• Dereferencing a null pointer means trying to access the memory location pointed by the null pointer.

• This results in a segmentation fault or access violation, as the null pointer does not point to a valid memory address.

• The operating system detects the illegal memory access and terminates the program t...read more
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Q1. OOPs Concepts: Abstraction, Encapsulation, Inheritance , Polymorphism
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Q2. Count number of elements in an array in python.
Ans. 
Use len() function to count number of elements in an array in Python.
• Use len() function with the array as argument to get the count of elements.

• Example: array = ['apple', 'banana', 'cherry'] Count = len(array) # Output: 3
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Q3. Merge two arrays in sorted order.
Ans. 
Merge two sorted arrays nums1 and nums2 into nums1 in-place.
• Initialize pointers for nums1 and nums2 at the end of their elements

• Compare elements pointed by the two pointers and place larger element at end of nums1

• Repeat until all elements from nums2 have been merged into nums1
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Q4. Difference between list and tuple
Ans. 
List is mutable, tuple is immutable in Python.
• List can be modified after creation, tuple cannot.

• List is defined using square brackets [], tuple using parentheses ().

• List is used for collections of items that may change, tuple for fixed collections.

• Example: list_example = [1, 2, 3], tuple_example = (4, 5, 6)
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Q5. One regex question and one file handling question in python
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Psuedo code of binary search. and some OOPs concept.

Q1. What is leakage current in cmos
Ans. 
Leakage current in CMOS refers to the small amount of current that flows through the transistors when they are in the off state.
• Leakage current occurs due to the imperfect insulation between the source and drain terminals of the transistors.

• It is an undesirable phenomenon as it leads to power dissipation and can affect the performance and reliability of CMOS circuits.

• Leakage current can be categorized into subthreshold...read more
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Q2. What are the differnet mosfet terminals
Ans. 
The different terminals of a MOSFET are the gate, source, and drain.
• The gate terminal controls the flow of current between the source and drain.

• The source terminal is where the current enters the MOSFET.

• The drain terminal is where the current exits the MOSFET.

• The gate-source voltage determines the conductivity of the channel between the source and drain.

• Examples of MOSFETs include enhancement-mode and depletion-mode MO
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Q3. What is ohms law
Ans. 
Ohm's law states that the current flowing through a conductor is directly proportional to the voltage applied across it and inversely proportional to its resistance.
• Ohm's law is expressed as V = IR, where V is the voltage, I is the current, and R is the resistance.

• It helps in understanding the relationship between voltage, current, and resistance in an electrical circuit.

• For example, if the voltage across a resistor is...read more
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Q4. Why current flow direction is opposite to the electron flow
Ans. 
The direction of current flow is opposite to the direction of electron flow due to historical convention.
• The concept of current flow was developed before the discovery of electrons.

• Benjamin Franklin proposed the convention of positive charge carriers, which led to the opposite direction of current flow.

• In reality, electrons are negatively charged and flow from the negative terminal to the positive terminal of a power s...read more
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Q5. What is an inductor
Ans. 
An inductor is a passive electronic component that stores energy in a magnetic field when current flows through it.
• Inductors are typically made of a coil of wire wound around a core material.

• They are used in electronic circuits to control the flow of current and store energy.

• Inductors can be found in various applications such as power supplies, filters, and oscillators.

• They are measured in units called henries (H).

• Indu...read more
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