PoolAllocator.h

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/*
 * Copyright (C) 2015 Niek Linnenbank
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef __LIBALLOC_POOLALLOCATOR_H
#define __LIBALLOC_POOLALLOCATOR_H
 
#include <Types.h>
#include <Macros.h>
#include "Allocator.h"
#include "BitAllocator.h"
 
class PoolAllocator : public Allocator
{
  private:
 
    static const Size MinimumPoolSize = 2;
 
    static const Size MaximumPoolSize = 27;
 
    static const u32 ObjectSignature = 0xF7312A56;
 
    typedef struct Pool : public BitAllocator
    {
        Pool(const Range & range,
             const Size objectSize,
             const Size bitmapSize,
             u8 *bitmap)
        : BitAllocator(range, objectSize, bitmap)
        , prev(ZERO)
        , next(ZERO)
        , index(0)
        , bitmapSize(bitmapSize)
        {
        }
 
        Pool *prev;            
        Pool *next;            
        Size index;            
        const Size bitmapSize; 
    } Pool;
 
    typedef struct ObjectPrefix
    {
        u32 signature;  
        Pool *pool;     
    } ObjectPrefix;
 
    typedef struct ObjectPostfix
    {
        u32 signature;  
    } ObjectPostfix;
 
  public:
 
    PoolAllocator(Allocator *parent);
 
    virtual Size size() const;
 
    virtual Size available() const;
 
    virtual Result allocate(Range & args);
 
    virtual Result release(const Address addr);
 
  private:
 
    Size calculateObjectSize(const Size index) const;
 
    Size calculateObjectCount(const Size objectSize) const;
 
    void calculateUsage(Size & totalSize, Size & totalUsed) const;
 
    Pool * retrievePool(const Size inputSize);
 
    Pool * allocatePool(const uint index, const Size objectCount);
 
    Result releasePool(Pool *pool);
 
  private:
 
    Pool *m_pools[MaximumPoolSize + 1];
};
 
#endif /* __LIBALLOC_POOLALLOCATOR_H */