drwnCompressionBuffer.h

/*****************************************************************************
** DARWIN: A FRAMEWORK FOR MACHINE LEARNING RESEARCH AND DEVELOPMENT
** Distributed under the terms of the BSD license (see the LICENSE file)
** Copyright (c) 2007-2015, Stephen Gould
** All rights reserved.
**
******************************************************************************
** FILENAME:    drwnCompressionBuffer.h
** AUTHOR(S):   Stephen Gould <stephen.gould@anu.edu.au>
**
*****************************************************************************/

#pragma once

#include <vector>
#include "Eigen/Core"

using namespace std;
using namespace Eigen;

// drwnCompressionBuffer ----------------------------------------------------

class drwnCompressionBuffer {
 protected:
    unsigned char *_data;
    unsigned int _bytesAllocated;
    unsigned int _bytesOriginal;
    unsigned int _bytesCompressed;

#ifdef DRWN_DEBUG_STATISTICS
    static unsigned _dbRefCount;
    static unsigned _dbOriginalBytes;
    static unsigned _dbCompressedBytes;
#endif
        
 public:
    drwnCompressionBuffer();
    ~drwnCompressionBuffer();

    unsigned int originalBytes() const { return _bytesOriginal; }
    unsigned int compressedBytes() const { return _bytesCompressed; }

    void compress(const unsigned char *data, unsigned int size);
    void decompress(unsigned char *data) const;
    
    size_t numBytesOnDisk() const;
    bool write(ostream& os) const;
    bool read(istream& is);

    drwnCompressionBuffer clone() const;
    void free();
};

// compression utility functions --------------------------------------------

drwnCompressionBuffer drwnCompressVector(const VectorXd& x);
drwnCompressionBuffer drwnCompressMatrix(const MatrixXd& x);
VectorXd drwnDecompressVector(const drwnCompressionBuffer& buffer, int rows);
MatrixXd drwnDecompressMatrix(const drwnCompressionBuffer& buffer, int rows, int cols);