// CPU scheduling simulation

#include "sched.h"

void fcfs::schedule(int nextproc, int timeindex, linked_list<pcb*>* run)
{
  pcb* temp;

  if (nextproc)
  {
    temp = new pcb;
    temp->execution_time = nextproc;
    temp->time_remaining = nextproc;
    temp->start_time = timeindex;
    temp->exit_time = 0;   // Just in case of wierdness

    run->insert_tail(temp);
  }
  run->seek_head();   // Just to be sure
}

// ---------------------------------------------------------------------

void rr::schedule(int nextproc, int timeindex, linked_list<pcb*>* run)
{
  pcb* temp;

  if (nextproc)
  {
    temp = new pcb;
    temp->execution_time = nextproc;
    temp->time_remaining = nextproc;
    temp->start_time = timeindex;
    temp->exit_time = 0;   // Just in case of wierdness

    run->insert_tail(temp);
  }

  // rotate the run queue
  if (run->node_count() > 1)
    run->insert_tail(run->remove_head());

  run->seek_head();   // Just to be sure
}

// ---------------------------------------------------------------------

void sjn::schedule(int nextproc, int timeindex, linked_list<pcb*>* run)
{
  pcb* temp;

  if (nextproc)
  {
    temp = new pcb;
    temp->execution_time = nextproc;
    temp->time_remaining = nextproc;
    temp->start_time = timeindex;
    temp->exit_time = 0;   // Just in case of wierdness

    run->seek_head();
    if (run->current() != NULL)
      run->next();

    while ((run->current() != NULL) && 
           (run->current()->execution_time <= temp->execution_time))
      run->next();

    if (run->current() == NULL)
    {
      run->insert_tail(temp);
    }
    else
    {
      run->insert_after(temp);
    }
  }

  run->seek_head();   // Just to be sure
}