Add thread save and restore processor context

src/kernel/system.rs

@@ -1,3 +1,5 @@
+use std::cell::RefCell;
+
 use crate::simulator::machine::Machine;
 
 use super::thread_manager::ThreadManager;
@@ -14,7 +16,7 @@ use super::thread_manager::ThreadManager;
 /// - The scheduler which acts upon these threads
 #[derive(PartialEq)]
 pub struct System<'a> {
-    g_machine: Machine,
+    g_machine: RefCell<Machine>,
     thread_manager: ThreadManager<'a>
 }
 
@@ -23,7 +25,7 @@ impl<'a> System<'a> {
     /// System constructor
     pub fn new(machine: Machine) -> System<'a> {
         Self {
-            g_machine: machine,
+            g_machine: RefCell::new(machine),
             thread_manager: ThreadManager::new()
         }
     }
@@ -37,14 +39,14 @@ impl<'a> System<'a> {
     /// Returns the Machine
     /// 
     /// Useful to access RAM, devices, ...
-    pub fn get_g_machine(&mut self) -> &mut Machine {
-        &mut self.g_machine
+    pub fn get_g_machine(&self) -> &RefCell<Machine> {
+        &self.g_machine
     }
 
     // Setters
 
     /// Assign a machine to the system
-    pub fn set_g_machine(&mut self, machine: Machine) {
+    pub fn set_g_machine(&mut self, machine: RefCell<Machine>) {
         self.g_machine = machine
     }