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/*! \file btGenericPoolAllocator.cpp
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\author Francisco Leon Najera. email projectileman@yahoo.com
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General purpose allocator class
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Bullet Continuous Collision Detection and Physics Library
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Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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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.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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#include "btGenericPoolAllocator.h"
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/// *************** btGenericMemoryPool ******************///////////
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size_t btGenericMemoryPool::allocate_from_free_nodes(size_t num_elements)
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size_t ptr = BT_UINT_MAX;
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if(m_free_nodes_count == 0) return BT_UINT_MAX;
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// find an avaliable free node with the correct size
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size_t revindex = m_free_nodes_count;
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while(revindex-- && ptr == BT_UINT_MAX)
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if(m_allocated_sizes[m_free_nodes[revindex]]>=num_elements)
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if(ptr == BT_UINT_MAX) return BT_UINT_MAX; // not found
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ptr = m_free_nodes[revindex];
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// post: ptr contains the node index, and revindex the index in m_free_nodes
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size_t finalsize = m_allocated_sizes[ptr];
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finalsize -= num_elements;
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m_allocated_sizes[ptr] = num_elements;
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// post: finalsize>=0, m_allocated_sizes[ptr] has the requested size
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if(finalsize>0) // preserve free node, there are some free memory
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m_free_nodes[revindex] = ptr + num_elements;
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m_allocated_sizes[ptr + num_elements] = finalsize;
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else // delete free node
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m_free_nodes[revindex] = m_free_nodes[m_free_nodes_count-1];
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size_t btGenericMemoryPool::allocate_from_pool(size_t num_elements)
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if(m_allocated_count+num_elements>m_max_element_count) return BT_UINT_MAX;
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size_t ptr = m_allocated_count;
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m_allocated_sizes[m_allocated_count] = num_elements;
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m_allocated_count+=num_elements;
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void btGenericMemoryPool::init_pool(size_t element_size, size_t element_count)
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m_allocated_count = 0;
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m_free_nodes_count = 0;
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m_element_size = element_size;
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m_max_element_count = element_count;
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m_pool = (unsigned char *) btAlignedAlloc(m_element_size*m_max_element_count,16);
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m_free_nodes = (size_t *) btAlignedAlloc(sizeof(size_t)*m_max_element_count,16);
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m_allocated_sizes = (size_t *) btAlignedAlloc(sizeof(size_t)*m_max_element_count,16);
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for (size_t i = 0;i< m_max_element_count;i++ )
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m_allocated_sizes[i] = 0;
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void btGenericMemoryPool::end_pool()
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btAlignedFree(m_pool);
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btAlignedFree(m_free_nodes);
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btAlignedFree(m_allocated_sizes);
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m_allocated_count = 0;
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m_free_nodes_count = 0;
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//! Allocates memory in pool
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\param size_bytes size in bytes of the buffer
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void * btGenericMemoryPool::allocate(size_t size_bytes)
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size_t module = size_bytes%m_element_size;
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size_t element_count = size_bytes/m_element_size;
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if(module>0) element_count++;
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size_t alloc_pos = allocate_from_free_nodes(element_count);
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// a free node is found
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if(alloc_pos != BT_UINT_MAX)
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return get_element_data(alloc_pos);
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// allocate directly on pool
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alloc_pos = allocate_from_pool(element_count);
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if(alloc_pos == BT_UINT_MAX) return NULL; // not space
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return get_element_data(alloc_pos);
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bool btGenericMemoryPool::freeMemory(void * pointer)
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unsigned char * pointer_pos = (unsigned char *)pointer;
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unsigned char * pool_pos = (unsigned char *)m_pool;
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if(pointer_pos<pool_pos) return false;//other pool
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size_t offset = size_t(pointer_pos - pool_pos);
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if(offset>=get_pool_capacity()) return false;// far away
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// find free position
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m_free_nodes[m_free_nodes_count] = offset/m_element_size;
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m_free_nodes_count++;
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/// *******************! btGenericPoolAllocator *******************!///
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btGenericPoolAllocator::~btGenericPoolAllocator()
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for (i=0;i<m_pool_count;i++)
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m_pools[i]->end_pool();
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btAlignedFree(m_pools[i]);
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btGenericMemoryPool * btGenericPoolAllocator::push_new_pool()
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if(m_pool_count >= BT_DEFAULT_MAX_POOLS) return NULL;
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btGenericMemoryPool * newptr = (btGenericMemoryPool *)btAlignedAlloc(sizeof(btGenericMemoryPool),16);
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m_pools[m_pool_count] = newptr;
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m_pools[m_pool_count]->init_pool(m_pool_element_size,m_pool_element_count);
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void * btGenericPoolAllocator::failback_alloc(size_t size_bytes)
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btGenericMemoryPool * pool = NULL;
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if(size_bytes<=get_pool_capacity())
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pool = push_new_pool();
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if(pool==NULL) // failback
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return btAlignedAlloc(size_bytes,16);
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return pool->allocate(size_bytes);
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bool btGenericPoolAllocator::failback_free(void * pointer)
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btAlignedFree(pointer);
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//! Allocates memory in pool
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\param size_bytes size in bytes of the buffer
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void * btGenericPoolAllocator::allocate(size_t size_bytes)
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while(i<m_pool_count && ptr == NULL)
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ptr = m_pools[i]->allocate(size_bytes);
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return failback_alloc(size_bytes);
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bool btGenericPoolAllocator::freeMemory(void * pointer)
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while(i<m_pool_count && result == false)
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result = m_pools[i]->freeMemory(pointer);
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if(result) return true;
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return failback_free(pointer);
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/// ************** STANDARD ALLOCATOR ***************************///
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#define BT_DEFAULT_POOL_SIZE 32768
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#define BT_DEFAULT_POOL_ELEMENT_SIZE 8
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class GIM_STANDARD_ALLOCATOR: public btGenericPoolAllocator
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GIM_STANDARD_ALLOCATOR():btGenericPoolAllocator(BT_DEFAULT_POOL_ELEMENT_SIZE,BT_DEFAULT_POOL_SIZE)
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GIM_STANDARD_ALLOCATOR g_main_allocator;
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void * btPoolAlloc(size_t size)
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return g_main_allocator.allocate(size);
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void * btPoolRealloc(void *ptr, size_t oldsize, size_t newsize)
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void * newptr = btPoolAlloc(newsize);
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size_t copysize = oldsize<newsize?oldsize:newsize;
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memcpy(newptr,ptr,copysize);
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void btPoolFree(void *ptr)
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g_main_allocator.freeMemory(ptr);