Bitmap16.h

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/*
 
Copyright (c) 2004, Cornell University
All rights reserved.
 
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   - Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
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       documentation and/or other materials provided with the distribution.
   - Neither the name of Cornell University nor the names of its
       contributors may be used to endorse or promote products derived from
       this software without specific prior written permission.
 
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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*/


/////////////////////////////////////////////////////////////////////
///
/// Bitmap16.h
///
/////////////////////////////////////////////////////////////////////
#ifndef __Bitmap16_H__
#define __Bitmap16_H__

#include <assert.h>
#include <memory.h>
#include "Tables.h"

/////////////////////////////////////////////////////////////////////
/// @addtogroup BitmapProcessingGroup Bitmap Processing
/** @{ */

/////////////////////////////////////////////////////////////////////
/// A vertical representation of the data. It handles both uncompressed
///  and compressed data.
///  <p>
/// This bitmap can represent customers with up to 16 transactions since it
///  allocates exactly 16 bits per customer
/////////////////////////////////////////////////////////////////////
class Bitmap16
{
    friend class SeqBitmap;

public:

    static void Init();
    static void Destroy();

    static int CalcSize (int numCust)
    {
        if (numCust % 2 == 0)
        {
            return (numCust / 2) * SIZE_USHORT;
        }
        else
            return (numCust / 2 + 1) * SIZE_USHORT;
    }

    /////////////////////////////////////////////////////////////////////
    /// Allocate the memory for Bitmap16 for this many customers
    ///
    /// @param numCustomers  # of customers
    /// @param memory
    /////////////////////////////////////////////////////////////////////
    Bitmap16(int numCustomers, unsigned short*& memory)
    {
        _numCust = numCustomers;

        if (_numCust % 2 == 0)
            _memSizeInt = _numCust / 2;
        else
            _memSizeInt = _numCust / 2 + 1;

        _memSizeShort = _memSizeInt * SHORT_PER_INT;
        //_memory = new unsigned short[_memSizeShort];
        _memory = memory;
        memory += _memSizeShort * SIZE_USHORT;
        memset(_memory, 0, _memSizeShort * SIZE_USHORT);
    };

    /////////////////////////////////////////////////////////////////////
    /// Copy constructor
    ///
    /// @param b             Bitmap to copy
    /// @param memory
    /////////////////////////////////////////////////////////////////////
    Bitmap16(Bitmap16 &b, unsigned short *&memory)
    {
        // copy information from the source bitmap
        _memSizeShort = b._memSizeShort;
        _memSizeInt = b._memSizeInt;
        _numCust = b._numCust;
        //_memory = new unsigned short[b._memSizeShort];
        _memory = memory;
        memory += _memSizeShort * SIZE_USHORT;
        memcpy(_memory, b._memory, _memSizeShort * SIZE_USHORT);
    };

    /////////////////////////////////////////////////////////////////////
    /// Destructor (does nothing)
    /////////////////////////////////////////////////////////////////////
    ~Bitmap16()
    {
        //if (_memory)
        // delete [] _memory;
    };

    /////////////////////////////////////////////////////////////////////
    /// Pop this bitmap's memory from the global stack (allocation is done in
    /// the constructor, but deallocation is not done in the destructor
    /////////////////////////////////////////////////////////////////////
    void Deallocate(unsigned short *&memory)
    {
        memory -= (_memSizeShort * SIZE_USHORT);
    };

    /////////////////////////////////////////////////////////////////////
    /// Fill in a 1 in a certain position
    ///
    /// @param j             bit position in Bitmap to be changed
    /////////////////////////////////////////////////////////////////////
    void FillEmptyPosition(int j)
    {
        // Locate correct short in the bitmap
        int i = j / BITS_PER_SHORT;

        // switch on correct bit
        _memory[i] = _memory[i] | Bit16Table[(j % BITS_PER_SHORT )];
    };

    // --- anding and oring two bitmap16s
    void Or(const Bitmap16 &b1, const Bitmap16 &b2);
    void And(const Bitmap16 &b1, const Bitmap16 &b2);

    // count the number of customers
    int Count();
    void CreateSBitmap(const Bitmap16 &iBitmap);
    void CreateCBitmap(const Bitmap16 &iBitmap);

    // ----------------------- static variables ----------------------
    /// counters for performance measurements
    static int _countOr;
    static int _countAnd;
    static int _countCount;
    static int _countCreateSBitmap;
    static int _countCreateCBitmap;

    /// lookup table for counting
    static const int _lookupTableSize;

    /// lookup table for creating a s-bitmap from an i-bitmap
    static int* _sBitmapLookupTable;

    /// lookup table for creating a c-bitmap for compression
    static int* _cBitmapLookupTable;

    int getIntSize() const
    {
        return _memSizeInt;
    }

private:
    // --- private variables
    unsigned short* _memory;    ///< where data is stored
    int _memSizeInt;            ///< size of memory allocated in sizeof(int)
    int _memSizeShort;          ///< size of memory allocated in sizeof(short)
    int _numCust;               ///< number of customers

}
; // class Bitmap16

/** @} */
#endif

---