int
main (void)
{
PCB *q1 = NULL;
PCB *p1 = pcb_new(0, 1);
PCB *p2 = pcb_new(3, 2);
PCB *p3 = pcb_new(2, 3);
PCB *p4 = pcb_new(1, 4);
PCB *p5 = pcb_new(4, 5);
PCB *x1;
q1 = p1;
pcb_enqueue(p2, &q1);
pcb_enqueue(p3, &q1);
pcb_enqueue(p4, &q1);
pcb_enqueue(p5, &q1);
pcb_print_list(q1);
x1 = pcb_dequeue(&q1);
pcb_print_list(q1);
pcb_remove(p5, &q1);
pcb_print_list(q1);
return 0;
}
/* Move head of userqueue to feedback queues */
void enqueue_roundrobin() {
PcbPtr process;
while (user_queue) { // while there are items in the user queue
if (check_resource(io_resources,user_queue) == 1 && memChk(memory,user_queue->mbytes)){ // if resources/memory can be allocated for the given process
process = pcb_dequeue(&user_queue);
process->memory = memAlloc(memory,process->mbytes); // allocating memory
if (process->memory) { // making sure it is not null
process->memory->id = process->id;
}
io_resources = allocate_resource(io_resources,process);
switch (process->priority) {
case 0:
break;
case 1:
p1_queue = pcb_enqueue(p1_queue,process);
break;
case 2:
p2_queue = pcb_enqueue(p2_queue,process);
break;
case 3:
p3_queue = pcb_enqueue(p3_queue,process);
break;
default:
fprintf(stderr, "Error. Priority not correctly set. Process ID: %d Priority: %d\n",process->id,process->priority);
break;
}
}
else { // leave the while loop when the above condition fails
break;
}
}
}
/* Move input->head of queue to user queue */
void enqueue_user_real_queues(){
PcbPtr process;
while(input_queue && input_queue->arrival_time <= clock_time) { // enqueue onto user/real queues when arrival time is reached
process = pcb_dequeue(&input_queue);
if (process->priority == 0) { // real time queue
realtime_queue = pcb_enqueue(realtime_queue,process);
}
else {
user_queue = pcb_enqueue(user_queue,process);
}
}
}
/* Checks for currently running processes. Stops it if time is up, Pauses it if queue is not empty */
PcbPtr running_processes() {
if (current_process) { // if there is a process running
current_process->remaining_cpu_time = current_process->remaining_cpu_time -1; // decrement time
if (current_process->remaining_cpu_time <= 0 || (current_process->processor_time - current_process->remaining_cpu_time >= 20)) { // processing time is completed
pcb_terminate(current_process);
if (current_process->priority > 0) { // not real time
io_resources = free_resource(io_resources,current_process);
}
/* Free memory relating to the finished process*/
if (current_process->priority != 0) {
memFree(current_process->memory);
}
pcb_free(current_process);
current_process = NULL;
}
else if (realtime_queue || p1_queue || p2_queue || p3_queue){ // suspend and enqueue process back to roundrobin if other waiting processes
if (current_process->priority == 0) { //real time process
return current_process;
}
current_process = pcb_suspend(current_process);
if (current_process-> priority < 3 && current_process->priority != 0){ // reduce priority
current_process->priority = current_process->priority +1 ;
}
switch (current_process->priority) {
case 1:
p1_queue = pcb_enqueue(p1_queue,current_process);
break;
case 2:
p2_queue = pcb_enqueue(p2_queue,current_process);
break;
case 3:
p3_queue = pcb_enqueue(p3_queue,current_process);
break;
default:
fprintf(stderr, "Error. Priority is out of bounds\n");
}
current_process = NULL;
}
}
return current_process;
}
