MemoryAllocator.h

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Contributor(s): Tao Ju
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#ifndef MEMORYALLOCATOR_H
#define MEMORYALLOCATOR_H

#include <stdio.h>
#include <stdlib.h>

#define HEAP_BASE 16
#define UCHAR unsigned char

class VirtualMemoryAllocator
{
public:
    virtual UCHAR * allocate( ) = 0 ;
    virtual void deallocate( UCHAR * obj ) = 0 ;
    virtual void destroy( ) = 0 ;
    virtual void printInfo( ) = 0 ;

    virtual int getAllocated( ) = 0 ;
    virtual int getAll( ) = 0 ;
    virtual int getBytes( ) = 0 ;
};

template < int N >
class MemoryAllocator : public VirtualMemoryAllocator
{
private:

    int HEAP_UNIT, HEAP_MASK ;

    UCHAR ** data ;

    UCHAR *** stack ;

    int datablocknum ;

    int stackblocknum ;

    int stacksize ;

    int available ;

    void allocateDataBlock ( )
    {
        // Allocate a data block
        datablocknum += 1 ;
        data = ( UCHAR ** )realloc( data, sizeof ( UCHAR * ) * datablocknum ) ;
        data[ datablocknum - 1 ] = ( UCHAR * )malloc( HEAP_UNIT * N ) ;

        // Update allocation stack
        for ( int i = 0 ; i < HEAP_UNIT ; i ++ )
        {
            stack[ 0 ][ i ] = ( data[ datablocknum - 1 ] + i * N ) ;
        }
        available = HEAP_UNIT ;
    }

    void allocateStackBlock( )
    {
        // Allocate a stack block
        stackblocknum += 1 ;
        stacksize += HEAP_UNIT ;
        stack = ( UCHAR *** )realloc( stack, sizeof ( UCHAR ** ) * stackblocknum ) ;
        stack[ stackblocknum - 1 ] = ( UCHAR ** )malloc( HEAP_UNIT * sizeof ( UCHAR * ) ) ;
    }


public:
    MemoryAllocator( )
    {
        HEAP_UNIT = 1 << HEAP_BASE ;
        HEAP_MASK = ( 1 << HEAP_BASE ) - 1 ;

        data = ( UCHAR ** )malloc( sizeof( UCHAR * ) ) ;
        data[ 0 ] = ( UCHAR * )malloc( HEAP_UNIT * N ) ;
        datablocknum = 1 ;

        stack = ( UCHAR *** )malloc( sizeof ( UCHAR ** ) ) ;
        stack[ 0 ] = ( UCHAR ** )malloc( HEAP_UNIT * sizeof ( UCHAR * ) ) ;
        stackblocknum = 1 ;
        stacksize = HEAP_UNIT ;
        available = HEAP_UNIT ;

        for ( int i = 0 ; i < HEAP_UNIT ; i ++ )
        {
            stack[ 0 ][ i ] = ( data[ 0 ] + i * N ) ;
        }
    }

    void destroy( )
    {
        int i ;
        for ( i = 0 ; i < datablocknum ; i ++ )
        {
            free( data[ i ] ) ;
        }
        for ( i = 0 ; i < stackblocknum ; i ++ )
        {
            free( stack[ i ] ) ;
        }
        free( data ) ;
        free( stack ) ;
    }

    UCHAR * allocate ( )
    {
        if ( available == 0 )
        {
            allocateDataBlock ( ) ;
        }

        // printf("Allocating %d\n", header[ allocated ]) ;
        available -- ;
        return stack[ available >> HEAP_BASE ][ available & HEAP_MASK ] ;
    }

    void deallocate ( UCHAR * obj )
    {
        if ( available == stacksize )
        {
            allocateStackBlock ( ) ;
        }

        // printf("De-allocating %d\n", ( obj - data ) / N ) ;
        stack[ available >> HEAP_BASE ][ available & HEAP_MASK ] = obj ;
        available ++ ;
        // printf("%d %d\n", allocated, header[ allocated ]) ;
    }

    void printInfo ( )
    {
        printf("Bytes: %d Used: %d Allocated: %d Maxfree: %d\n", getBytes(), getAllocated(), getAll(), stacksize ) ;
    }

    int getAllocated( )
    {
        return HEAP_UNIT * datablocknum - available ;   
    };

    int getAll( )
    {
        return HEAP_UNIT * datablocknum ;
    };

    int getBytes( )
    {
        return N ;  
    };
};

#endif