Simplify mutex

kernel/include/mutex.hpp

@@ -8,23 +8,43 @@
 #ifndef MUTEX_H
 #define MUTEX_H
 
-#include "semaphore.hpp"
+//TODO Ideally this should simply be a wrapper around a semaphore
 
 struct mutex {
 private:
-    semaphore sem;
+    spinlock lock;
+    volatile size_t value;
+    circular_buffer<scheduler::pid_t, 16> queue;
 
 public:
     void init(){
-        sem.init(1);
+        value = 1;
     }
 
     void acquire(){
-        sem.wait();
+        std::lock_guard<spinlock> l(lock);
+
+        if(value > 0){
+            value = 0;
+        } else {
+            auto pid = scheduler::get_pid();
+            queue.push(pid);
+            scheduler::block_process(pid);
+        }
     }
 
     void release(){
-        sem.signal();
+        std::lock_guard<spinlock> l(lock);
+
+        if(queue.empty()){
+            value = 1;
+        } else {
+            auto pid = queue.pop();
+            scheduler::unblock_process(pid);
+
+            //No need to increment value, the process won't
+            //decrement it
+        }
     }
 };