PhantomBuffer.hxx

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/*
 * Copyright (c) 2001-2004 MUSIC TECHNOLOGY GROUP (MTG)
 *                         UNIVERSITAT POMPEU FABRA
 *
 *
 * This program 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#ifndef _PHANTOM_BUFFER_H
#define _PHANTOM_BUFFER_H


#include <vector>
#include "Assert.hxx"

namespace CLAM {

        template<class T>
        class PhantomBuffer 
        {
        public:
                PhantomBuffer();
                T*   Read(unsigned int pos, unsigned int size);

                void Touch(unsigned int pos, unsigned int size);

                void Write(unsigned int pos, unsigned int size,const T* data);

                unsigned LogicalSize() const {return mLogicalSize;}
                
                unsigned int PhantomSize() const { return mBuffer.size() - mLogicalSize; }

                void Resize(unsigned int size,
                            unsigned int phantom,
                            unsigned int insert_pos);
        
                void FulfilsInvariant() const;

        private:
                void UpdatePhantom(unsigned int pos, unsigned int size);
                void UpdateBeginning(unsigned int pos, unsigned int size);

                unsigned int AllocatedSize() const
                { 
                        return mBuffer.size(); 
                }

        
                // attributes
                std::vector<T> mBuffer;
                unsigned mLogicalSize;
        };

        
        template<class T>
        PhantomBuffer<T>::PhantomBuffer()
                : mLogicalSize(0) 
        {}


        template<class T>
        void PhantomBuffer<T>::UpdatePhantom(unsigned int pos, unsigned int size)
        {
                CLAM_DEBUG_ASSERT(pos+size <= PhantomSize(),
                                 "PhantomBuffer::UpdatePhantom():"
                                 "Requested region falls outside phantom zone");
                unsigned int s,d;
                for (s=pos, d=mLogicalSize+pos; s<pos+size; s++, d++)
                        mBuffer[d] = mBuffer[s];
        }

        template<class T>
        void PhantomBuffer<T>::UpdateBeginning(unsigned int pos, unsigned int size)
        {
                CLAM_DEBUG_ASSERT(pos+size <= PhantomSize(),
                                 "PhantomBuffer::UpdateBeginning():"
                                 "Requested region falls outside beginning zone");
                unsigned int s,d;
                for (d=pos, s=mLogicalSize+pos; d<size; d++, s++)
                        mBuffer[d] = mBuffer[s];
        }


        template<class T>
        void PhantomBuffer<T>::Resize(unsigned int newLogicalSize, unsigned int newPhantomSize, unsigned int insertionPos)
        {
                CLAM_ASSERT(insertionPos <= LogicalSize(),
                           "PhantomBuffer::Resize(): "
                           "Insertion position can not be greater than previous size.");
                CLAM_ASSERT(newPhantomSize <= newLogicalSize,
                           "PhantomBuffer::Resize(): Phantom Size can not be greater than size.");


                if ( newLogicalSize <= LogicalSize() )
                        return;

                CLAM_ASSERT(newPhantomSize >= PhantomSize(),
                           "PhantomBuffer::Resize(): PhantomSize can not be decreased.");

                unsigned int logicalElementsToInsert = newLogicalSize - LogicalSize();
                unsigned int phantomElementsToInsert = newPhantomSize - PhantomSize();

                typename std::vector<T>::iterator it = mBuffer.begin();
                it += insertionPos;
                mBuffer.insert(it, logicalElementsToInsert, T());

                mBuffer.insert( mBuffer.end(), phantomElementsToInsert,  T());
                //TODO update phantom

                mLogicalSize = newLogicalSize;
        }


        template<class T>
        T* PhantomBuffer<T>::Read(unsigned int pos, unsigned int size)
        {
                CLAM_DEBUG_ASSERT( (pos+size-1) <= ( AllocatedSize() ),
                                  "PhantomBuffer::Read(): Position outside bounds");
                return &mBuffer[pos];
        }


        template<class T>
        void PhantomBuffer<T>::Touch(unsigned int pos, unsigned int size)
        {
                CLAM_DEBUG_ASSERT( (pos+size) <= ( AllocatedSize() ),
                                  "PhantomBuffer::Write(): Position outside bounds");
                unsigned int writen_area_end = pos+size;

                if (writen_area_end > mLogicalSize)
                {
                        unsigned int update_start;
                        if (mLogicalSize > pos)
                                update_start = 0;
                        else
                                update_start = pos-mLogicalSize;
                        UpdateBeginning(update_start, writen_area_end - mLogicalSize - update_start);
                }
                else if ( pos < PhantomSize() )
                {
                        int update_end;
                        if (PhantomSize() < writen_area_end )
                                update_end = PhantomSize();
                        else
                                update_end = writen_area_end;
                        UpdatePhantom(pos,update_end-pos);
                }
        }


        template<class T>
        void PhantomBuffer<T>::Write(unsigned int pos, unsigned int size,const T* data)
        {
                CLAM_DEBUG_ASSERT( (pos+size) <= ( AllocatedSize() ),
                                  "PhantomBuffer::Write(): Position outside bounds");
                unsigned int s,d;

                for (s=0, d=pos; s<size; s++, d++)
                        mBuffer[d] = data[s];
                Touch(pos,size);
        }


        template<class T>
        void PhantomBuffer<T>::FulfilsInvariant() const
        {
                CLAM_ASSERT(mBuffer.size() == AllocatedSize(),
                           "PhantomBuffer<T>::FulfilsInvariant(): "
                           "internal vector size unconsistency");
                CLAM_ASSERT(PhantomSize() <= mLogicalSize,
                           "PhantomBuffer<T>::FulfilsInvariant(): "
                           "Phantom size biger than logical size");
                unsigned int i;
                for (i=0; i<PhantomSize(); i++)
                        CLAM_ASSERT(mBuffer[i] == mBuffer[i+mLogicalSize],
                                    "PhantomBuffer<T>::FulfilsInvariant(): "
                                    "Phantom data is unconsistent!");

        }

} // namespace CLAM

#endif

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