buffhandle.hpp

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/*
  BUFFHANDLE.hpp  -  Buffer handling support for the render engine

   Copyright (C)
     2008,            Hermann Vosseler <Ichthyostega@web.de>

  **Lumiera** is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version. See the file COPYING for further details.

*/

#ifndef ENGINE_BUFFHANDLE_H
#define ENGINE_BUFFHANDLE_H


#include "lib/error.hpp"
#include "lib/hash-value.h"
#include "steam/streamtype.hpp"


namespace steam {
namespace engine {
  namespace error = lumiera::error;
  
  using lib::HashVal;
  
  class BuffHandle;
  class BufferProvider;
  
  
  
  class BuffDescr
    {
    protected:
      BufferProvider* provider_;
      HashVal subClassification_;
      
      BuffDescr(BufferProvider& manager, HashVal detail)
        : provider_(&manager)
        , subClassification_(detail)
      { }
      
      friend class BufferProvider;
      friend class BuffHandle;
      
    public:
      // using standard copy operations
      
      bool verifyValidity()  const;
      size_t determineBufferSize() const;
      
      operator HashVal()  const { return subClassification_; }
      
      uint announce (uint count);
      BuffHandle lockBuffer();
    };
  
  
  
  
  class BuffHandle
    {
      using Buff = StreamType::ImplFacade::DataBuffer;  
      
      BuffDescr descriptor_;
      Buff*     pBuffer_;
      
      
    public:
      typedef Buff* PBuff;
      
      BuffHandle(BuffDescr const& typeInfo, void* storage = 0)
        : descriptor_(typeInfo)
        , pBuffer_(static_cast<PBuff>(storage))
        { }
      
      // using standard copy operations
      
      explicit operator bool()  const { return isValid(); }
      
      
      void emit();
      void release();
      
      
      template<typename BU>
      BU& create();
      
      template<typename BU>
      BU& accessAs();
      
      
      Buff&
      operator* ()  const
        {
          ENSURE (pBuffer_);
          return *pBuffer_;
        }
      
      bool
      isValid()  const
        {
          return bool(pBuffer_)
              && descriptor_.verifyValidity();
        }
      
      HashVal
      entryID()  const
        {
          return HashVal(descriptor_);
        }
      
      size_t
      size()  const
        {
          return descriptor_.determineBufferSize();
        }
      
    private:
      template<typename BU>
      void takeOwnershipFor();
      void takeOwnershipFor(BuffDescr const& type);
      
      void emergencyCleanup();
    };
  
  
  
  
}} // namespace steam::engine
#endif