OSTaskChangePrio: Dynamically Change Task Priority in Real-Time Operating System

The function 'OSTaskChangePrio' enables dynamic priority modification of tasks within a real-time operating system (RTOS). It accepts the old priority and the new priority as input parameters, returning an error code indicating the operation's success or failure.

Initially, the function verifies if the new priority already exists, returning an error if so. It then checks for the existence of the task associated with the provided old priority, returning an error if it is not found or if it is assigned to a mutex PIP.

The function subsequently calculates the new TCB (Task Control Block) fields. It removes the TCB from its original priority and places a pointer to the TCB at the newly assigned priority. If the task is in a ready state, it is marked as not ready and added to the ready list of the new priority. If the task is in a waiting state for an event, it is removed from the old priority wait list and added to the new priority wait list.

Finally, the function sets the task's new priority and TCB fields. If the kernel is currently running, it schedules the task with the highest priority. The function then returns an error code, signaling the success or failure of the operation.