I applied through a recruiter. The process took 3 weeks.

For the embedded C role I am interviewing for, there is the initial interview, in which you have to answer two coding questions, provide working code in C/C++. The interview time allocated was 45 minutes.

Problem Statement:

Given a byte array in network byte order, write an algorithm to find the starting bit position of the first occurrence of the 32-bit, big-endian pattern (0xFE6B2840) in the byte array. The pattern may or may not be byte aligned in the input.

The function htonl() and ntohl() are provided in the C library to convert the endian order from host to network order, and from network to host order respectively:

uint32_t htonl(uint32_t hostlong); uint32_t ntohl(uint32_t netlong);

Note: network byte order is big-endian, host byte order is little-endian.

Signature of function to implement: int findPattern(const uint32_t numBytes, const uint8_t data[])

Description of function parameters:

Input parameters:

• uint32_t numBytes - The number of bytes in the array named 'data'
• uint8_t data[] - The byte stream of data to search

Return:

• -1: if the given pattern (0xFE6B2840) is not found.
• -2: if the inputData is Null or the size of the 'data' is insufficient to find the pattern (0xFE6B2840).
• Otherwise, the pattern is found. Return the starting bit position of the pattern (0xFE6B2840).

Example 1 - Byte Aligned: Inputs:

• numBytes: 8
• data: { 0x00, 0x01, 0xFE, 0x6B, 0x28, 0x40, 0x02, 0x03 } Starting position is here at bit 16 Returns: 16

Example 2 - Non-byte Aligned: Image 2: This is the same as example 1, left-shifted by 1 bit! Inputs:

• numBytes: 8
• data: { 0x00, 0x03, 0xFC, 0xD6, 0x50, 0x80, 0x04, 0x06 } Starting position is here at bit 15 (least significant bit of the second byte of the input) Returns: 15