text: #pragma once
  
  #include <AK/NonnullRefPtr.h>
  #include <Kernel/Assertions.h>
  #include <Kernel/PhysicalAddress.h>
  
  class PhysicalPage {
      friend class MemoryManager;
      friend class PageDirectory;
      friend class VMObject;
  
  public:
      PhysicalAddress paddr() const { return m_paddr; }
  
      void ref()
      {
          ASSERT(m_retain_count);
          ++m_retain_count;
      }
  
      void deref()
      {
          ASSERT(m_retain_count);
          if (!--m_retain_count) {
              if (m_may_return_to_freelist)
                  move(*this).return_to_freelist();
              delete this;
          }
      }
  
      static NonnullRefPtr<PhysicalPage> create(PhysicalAddress, bool supervisor, bool may_return_to_freelist = true);
  
      u16 ref_count() const { return m_retain_count; }
  
  private:
      PhysicalPage(PhysicalAddress paddr, bool supervisor, bool may_return_to_freelist = true);
      ~PhysicalPage() {}
  
      void return_to_freelist() &&;
  
      u16 m_retain_count { 1 };
      bool m_may_return_to_freelist { true };
      bool m_supervisor { false };
      PhysicalAddress m_paddr;
  };
  