synchronize with semaphore

c_os/user/PreemptiveLoopThread.cc

@@ -6,12 +6,12 @@ void PreemptiveLoopThread::run() {
 
     int cnt = 0;
     while (true) {
-        // Basic synchronization by disabling PIT interrupts
-        cpu.disable_int();
+        // Basic synchronization by semaphore
+        sem->p();
 
         kout.setpos(55, this->id);
         kout << this->id << ": " << dec << cnt++ << endl;
 
-        cpu.enable_int();
+        sem->v();
     }
 }

c_os/user/PreemptiveLoopThread.h

@@ -3,17 +3,19 @@
 
 #include "kernel/Globals.h"
 #include "kernel/threads/Thread.h"
+#include "lib/Semaphore.h"
 
 class PreemptiveLoopThread : public Thread {
 
 private:
     int id;
+    Semaphore* sem;
 
     PreemptiveLoopThread(const PreemptiveLoopThread& copy) = delete;  // Verhindere Kopieren
 
 public:
     // Gibt der Loop einen Stack und eine Id.
-    PreemptiveLoopThread(int i) : id(i) {}
+    PreemptiveLoopThread(int i, Semaphore* sem) : id(i), sem(sem) {}
 
     // Zaehlt einen Zaehler hoch und gibt ihn auf dem Bildschirm aus.
     void run() override;

c_os/user/PreemptiveThreadDemo.cc

@@ -1,12 +1,18 @@
 #include "user/PreemptiveThreadDemo.h"
+#include "lib/Semaphore.h"
 
 void PreemptiveThreadDemo::run() {
+    kout << "PreemptiveThreadDemo ====================================" << endl;
+    kout << "Initializing Semaphore" << endl;
+    Semaphore* sem = new Semaphore(1); // Create this semaphore on the heap as this thread exits itself,
+                                       // so stack allocated objects will be lost
+
     kout << "Allocating LoopThread A" << endl;
-    Thread* cntA = new PreemptiveLoopThread(0);
+    Thread* cntA = new PreemptiveLoopThread(0, sem);
     kout << "Allocating LoopThread B" << endl;
-    Thread* cntB = new PreemptiveLoopThread(1);
+    Thread* cntB = new PreemptiveLoopThread(1, sem);
     kout << "Allocating LoopThread C" << endl;
-    Thread* cntC = new PreemptiveLoopThread(2);
+    Thread* cntC = new PreemptiveLoopThread(2, sem);
 
     kout << "Adding threads to ready queue" << endl;
     scheduler.ready(cntA);