Embedded Systems and C Online Test

A car company plans to extend its car computer system to offer Bluetooth connectivity with the owner's mobile phone.

Select all correct statements about the properties of such a connection.

(Select all acceptable answers.)

The following part of the C code distributes packets from the input track to the output track:

void* take_and_put(void *arg)
{
    sem_wait(&semaphore);
    take();
    sem_post(&semaphore);

    pthread_mutex_lock(&mutex);
    put();
    pthread_mutex_unlock(&mutex);

    return NULL;
}

Where semaphore and mutex are initialized with:

// int sem_init(sem_t *sem, int pshared, unsigned int value);
sem_init(&semaphore, 0, 3);
// int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr);
pthread_mutex_init(&mutex, NULL);

If the function take_and_put is repeatedly called by a large number of threads, select correct statements about the take_and_put function.

(Select all acceptable answers.)

Implement the function find_roots to find the roots of the quadratic equation: ax² + bx + c = 0. If the equation has only one solution, the function should return that solution as both roots. The equation will always have at least one solution.

The roots of the quadratic equation can be found with the following formula:

For example, the roots of the equation 2x² + 10x + 8 = 0 are -1 and -4.