disastrOS_schedule.c

#include <assert.h>
#include <unistd.h>
#include <stdio.h>
#include "disastrOS.h"
#include "disastrOS_syscalls.h"

// replaces the running process with the next one in the ready list
void internal_schedule() {

  if(DEBUG==1) printf("SONO NELLA INTERNAL_SCHEDULE\n");

  if (running) {
    disastrOS_debug("PREEMPT - %d ->", running->pid);
   }
  // at least one process should be in the running queue
  // if not, no preemption occurs
  
  // Sveglio i processi in base ai timer dati e li metto nella ready list
  TimerItem* elapsed_timer=0;
  PCB* previous_pcb=0;

  while( (elapsed_timer=TimerList_current(&timer_list, disastrOS_time)) ){
    PCB* pcb_to_wake=elapsed_timer->pcb;
    List_detach(&waiting_list, (ListItem*) pcb_to_wake);
    pcb_to_wake->status=Ready;
    pcb_to_wake->timer=0;
    List_insert(&ready_list, (ListItem*) previous_pcb, (ListItem*) pcb_to_wake);
    previous_pcb=pcb_to_wake;
    TimerList_removeCurrent(&timer_list);
  }


  if (ready_list.first){
    PCB* next_process=(PCB*) List_detach(&ready_list, ready_list.first);
    running->status=Ready;
    List_insert(&ready_list, ready_list.last, (ListItem*) running);
    next_process->status=Running;
    running=next_process;
  }
  //disastrOS_printStatus();
 
  if (running) {
    disastrOS_debug(" %d\n", running->pid);
  }
}