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      1 /*
      2 Copyright (c) 2003-2006 Gino van den Bergen / Erwin Coumans  http://continuousphysics.com/Bullet/
      3 
      4 This software is provided 'as-is', without any express or implied warranty.
      5 In no event will the authors be held liable for any damages arising from the use of this software.
      6 Permission is granted to anyone to use this software for any purpose,
      7 including commercial applications, and to alter it and redistribute it freely,
      8 subject to the following restrictions:
      9 
     10 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
     11 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
     12 3. This notice may not be removed or altered from any source distribution.
     13 */
     14 
     15 
     16 #ifndef _BT_POOL_ALLOCATOR_H
     17 #define _BT_POOL_ALLOCATOR_H
     18 
     19 #include "btScalar.h"
     20 #include "btAlignedAllocator.h"
     21 
     22 ///The btPoolAllocator class allows to efficiently allocate a large pool of objects, instead of dynamically allocating them separately.
     23 class btPoolAllocator
     24 {
     25 	int				m_elemSize;
     26 	int				m_maxElements;
     27 	int				m_freeCount;
     28 	void*			m_firstFree;
     29 	unsigned char*	m_pool;
     30 
     31 public:
     32 
     33 	btPoolAllocator(int elemSize, int maxElements)
     34 		:m_elemSize(elemSize),
     35 		m_maxElements(maxElements)
     36 	{
     37 		m_pool = (unsigned char*) btAlignedAlloc( static_cast<unsigned int>(m_elemSize*m_maxElements),16);
     38 
     39 		unsigned char* p = m_pool;
     40         m_firstFree = p;
     41         m_freeCount = m_maxElements;
     42         int count = m_maxElements;
     43         while (--count) {
     44             *(void**)p = (p + m_elemSize);
     45             p += m_elemSize;
     46         }
     47         *(void**)p = 0;
     48     }
     49 
     50 	~btPoolAllocator()
     51 	{
     52 		btAlignedFree( m_pool);
     53 	}
     54 
     55 	int	getFreeCount() const
     56 	{
     57 		return m_freeCount;
     58 	}
     59 
     60 	int getUsedCount() const
     61 	{
     62 		return m_maxElements - m_freeCount;
     63 	}
     64 
     65 	int getMaxCount() const
     66 	{
     67 		return m_maxElements;
     68 	}
     69 
     70 	void*	allocate(int size)
     71 	{
     72 		// release mode fix
     73 		(void)size;
     74 		btAssert(!size || size<=m_elemSize);
     75 		btAssert(m_freeCount>0);
     76         void* result = m_firstFree;
     77         m_firstFree = *(void**)m_firstFree;
     78         --m_freeCount;
     79         return result;
     80 	}
     81 
     82 	bool validPtr(void* ptr)
     83 	{
     84 		if (ptr) {
     85 			if (((unsigned char*)ptr >= m_pool && (unsigned char*)ptr < m_pool + m_maxElements * m_elemSize))
     86 			{
     87 				return true;
     88 			}
     89 		}
     90 		return false;
     91 	}
     92 
     93 	void	freeMemory(void* ptr)
     94 	{
     95 		 if (ptr) {
     96             btAssert((unsigned char*)ptr >= m_pool && (unsigned char*)ptr < m_pool + m_maxElements * m_elemSize);
     97 
     98             *(void**)ptr = m_firstFree;
     99             m_firstFree = ptr;
    100             ++m_freeCount;
    101         }
    102 	}
    103 
    104 	int	getElementSize() const
    105 	{
    106 		return m_elemSize;
    107 	}
    108 
    109 	unsigned char*	getPoolAddress()
    110 	{
    111 		return m_pool;
    112 	}
    113 
    114 	const unsigned char*	getPoolAddress() const
    115 	{
    116 		return m_pool;
    117 	}
    118 
    119 };
    120 
    121 #endif //_BT_POOL_ALLOCATOR_H
    122