text: //
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  // Copyright (c) 2008-2021 NVIDIA Corporation. All rights reserved.
  // Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
  // Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
  
  #ifndef PX_PHYSICS_COMMON_PTR_TABLE
  #define PX_PHYSICS_COMMON_PTR_TABLE
  
  #include "CmPhysXCommon.h"
  #include "common/PxPhysXCommonConfig.h"
  
  namespace physx {
  
  class PxSerializationContext;
  class PxDeserializationContext;
  
  namespace Cm {
  
  class PtrTableStorageManager {
    // This will typically be backed by a MultiPool implementation with fallback to the user
    // allocator. For MultiPool, when deallocating we want to know what the previously requested size was
    // so we can release into the right pool
  
  public:
    // capacity is in bytes
  
    virtual void **allocate(PxU32 capacity) = 0;
    virtual void deallocate(void **addr, PxU32 originalCapacity) = 0;
  
    // whether memory allocated at one capacity can (and should) be safely reused at a different capacity
    // allows realloc-style reuse by clients.
  
    virtual bool canReuse(PxU32 originalCapacity, PxU32 newCapacity) = 0;
  
  protected:
    virtual ~PtrTableStorageManager() {}
  };
  
  // specialized class to hold an array of pointers with extrinsic storage management,
  // serialization-compatible with 3.3.1 PtrTable
  //
  // note that extrinsic storage implies you *must* clear the table before the destructor runs
  //
  // capacity is implicit:
  // if the memory is not owned (i.e. came from deserialization) then the capacity is exactly mCount
  // else if mCount==0,  capacity is 0
  // else the capacity is the power of 2 >= mCount
  //
  // one implication of this is that if we want to add or remove a pointer from unowned memory, we always realloc
  
  struct PX_PHYSX_COMMON_API PtrTable {
    //= ATTENTION! =====================================================================================
    // Changing the data layout of this class breaks the binary serialization format.  See comments for
    // PX_BINARY_SERIAL_VERSION.  If a modification is required, please adjust the getBinaryMetaData
    // function.  If the modification is made on a custom branch, please change PX_BINARY_SERIAL_VERSION
    // accordingly.
    //==================================================================================================
  
    PtrTable();
    ~PtrTable();
  
    void add(void *ptr, PtrTableStorageManager &sm);
    void replaceWithLast(PxU32 index, PtrTableStorageManager &sm);
    void clear(PtrTableStorageManager &sm);
  
    PxU32 find(const void *ptr) const;
  
    PX_FORCE_INLINE PxU32 getCount() const { return mCount; }
    PX_FORCE_INLINE void *const *getPtrs() const { return mCount == 1 ? &mSingle : mList; }
    PX_FORCE_INLINE void **getPtrs() { return mCount == 1 ? &mSingle : mList; }
  
    // SERIALIZATION
  
    // 3.3.1 compatibility fixup: this implementation ALWAYS sets 'ownsMemory' if the size is 0 or 1
    PtrTable(const PxEMPTY) {
      mOwnsMemory = mCount < 2;
      if (mCount == 0)
        mList = NULL;
    }
  
    void exportExtraData(PxSerializationContext &stream);
    void importExtraData(PxDeserializationContext &context);
  
    static void getBinaryMetaData(physx::PxOutputStream &stream);
  
  private:
    void realloc(PxU32 oldCapacity, PxU32 newCapacity, PtrTableStorageManager &sm);
  
    union {
      void *mSingle;
      void **mList;
    };
  
    PxU16 mCount;
    bool mOwnsMemory;
    bool mBufferUsed; // dark magic in serialization requires this, otherwise redundant because it's logically equivalent
                      // to mCount == 1.
  };
  
  } // namespace Cm
  #if !PX_P64_FAMILY
  PX_COMPILE_TIME_ASSERT(sizeof(Cm::PtrTable) == 8);
  #endif
  
  } // namespace physx
  
  #endif
  