ChannelBufferElement.hpp

/***************************************************************************
  tag: Peter Soetens  Thu Oct 22 11:59:08 CEST 2009  ChannelBufferElement.hpp

                        ChannelBufferElement.hpp -  description
                           -------------------
    begin                : Thu October 22 2009
    copyright            : (C) 2009 Sylvain Joyeux
    email                : sylvain.joyeux@m4x.org

 ***************************************************************************
 *   This library 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;                 *
 *   version 2 of the License.                                             *
 *                                                                         *
 *   As a special exception, you may use this file as part of a free       *
 *   software library without restriction.  Specifically, if other files   *
 *   instantiate templates or use macros or inline functions from this     *
 *   file, or you compile this file and link it with other files to        *
 *   produce an executable, this file does not by itself cause the         *
 *   resulting executable to be covered by the GNU General Public          *
 *   License.  This exception does not however invalidate any other        *
 *   reasons why the executable file might be covered by the GNU General   *
 *   Public License.                                                       *
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 *   Lesser General Public License for more details.                       *
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 *   Foundation, Inc., 59 Temple Place,                                    *
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 ***************************************************************************/


#ifndef ORO_CHANNEL_BUFFER_ELEMENT_HPP
#define ORO_CHANNEL_BUFFER_ELEMENT_HPP

#include "../base/ChannelElement.hpp"
#include "../base/BufferInterface.hpp"

namespace RTT { namespace internal {

    template<typename T>
    class ChannelBufferElement : public base::ChannelElement<T>
    {
        typename base::BufferInterface<T>::shared_ptr buffer;
        typename base::ChannelElement<T>::value_t *last_sample_p;
    public:
        typedef typename base::ChannelElement<T>::param_t param_t;
        typedef typename base::ChannelElement<T>::reference_t reference_t;
    typedef typename base::ChannelElement<T>::value_t value_t;

        ChannelBufferElement(typename base::BufferInterface<T>::shared_ptr buffer)
            : buffer(buffer), last_sample_p(0) {}
            
    virtual ~ChannelBufferElement()
    {
        if(last_sample_p)
        buffer->Release(last_sample_p);
    }
 
        virtual bool write(param_t sample)
        {
            if (buffer->Push(sample))
                return this->signal();
            return true;
        }

        virtual FlowStatus read(reference_t sample, bool copy_old_data)
        {
        value_t *new_sample_p;
            if ( (new_sample_p = buffer->PopWithoutRelease()) ) {
        if(last_sample_p)
            buffer->Release(last_sample_p);
        
        last_sample_p = new_sample_p;
        sample = *new_sample_p;
                return NewData;
            }
            if (last_sample_p) {
        if(copy_old_data)
            sample = *(last_sample_p);
                return OldData;
            }
            return NoData;
        }

        virtual void clear()
        {
        if(last_sample_p)
        buffer->Release(last_sample_p);
        last_sample_p = 0;
            buffer->clear();
            base::ChannelElement<T>::clear();
        }

        virtual bool data_sample(param_t sample)
        {
            buffer->data_sample(sample);
            return base::ChannelElement<T>::data_sample(sample);
        }

        virtual T data_sample()
        {
            return buffer->data_sample();
        }
    };
}}

#endif