145 lines
5.6 KiB
C++
145 lines
5.6 KiB
C++
/********************************************************************************
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* ReactPhysics3D physics library, http://code.google.com/p/reactphysics3d/ *
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* Copyright (c) 2010-2013 Daniel Chappuis *
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*********************************************************************************
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* *
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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 *
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* use of this software. *
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* *
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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 *
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* freely, subject to the following restrictions: *
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* *
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* 1. The origin of this software must not be misrepresented; you must not claim *
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* that you wrote the original software. If you use this software in a *
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* product, an acknowledgment in the product documentation would be *
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* appreciated but is not required. *
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* *
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* 2. Altered source versions must be plainly marked as such, and must not be *
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* misrepresented as being the original software. *
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* *
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* 3. This notice may not be removed or altered from any source distribution. *
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* *
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********************************************************************************/
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#ifndef REACTPHYSICS3D_MEMORY_ALLOCATOR_H
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#define REACTPHYSICS3D_MEMORY_ALLOCATOR_H
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// Libraries
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#include "../configuration.h"
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/// ReactPhysics3D namespace
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namespace reactphysics3d {
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// Class MemoryAllocator
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/**
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* This class is used to efficiently allocate memory on the heap.
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* It allows us to allocate small blocks of memory (smaller or equal to 1024 bytes)
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* efficiently. This implementation is inspired by the small block allocator
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* described here : http://www.codeproject.com/useritems/Small_Block_Allocator.asp
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*/
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class MemoryAllocator {
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private :
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// -------------------- Internal Classes -------------------- //
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// Structure MemoryUnit
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/**
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* Represent a memory unit that is used for a single memory allocation
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* request.
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*/
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struct MemoryUnit {
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public :
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// -------------------- Attributes -------------------- //
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/// Pointer to the next memory unit inside a memory block
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MemoryUnit* nextUnit;
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};
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// Structure MemoryBlock
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/**
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* A memory block is a large piece of memory that is allocated once and that
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* will contain multiple memory unity.
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*/
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struct MemoryBlock {
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public :
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/// Pointer to the first element of a linked-list of memory unity.
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MemoryUnit* memoryUnits;
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};
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// -------------------- Constants -------------------- //
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/// Number of heaps
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static const uint NB_HEAPS = 128;
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/// Maximum memory unit size. An allocation request of a size smaller or equal to
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/// this size will be handled using the small block allocator. However, for an
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/// allocation request larger than the maximum block size, the standard malloc()
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/// will be used.
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static const size_t MAX_UNIT_SIZE = 1024;
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/// Size a memory chunk
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static const size_t BLOCK_SIZE = 16 * MAX_UNIT_SIZE;
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// -------------------- Attributes -------------------- //
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/// Size of the memory units that each heap is responsible to allocate
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static size_t mUnitSizes[NB_HEAPS];
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/// Lookup table that mape size to allocate to the index of the
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/// corresponding heap we will use for the allocation.
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static int mMapSizeToHeapIndex[MAX_UNIT_SIZE + 1];
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/// True if the mMapSizeToHeapIndex array has already been initialized
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static bool isMapSizeToHeadIndexInitialized;
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/// Pointers to the first free memory unit for each heap
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MemoryUnit* mFreeMemoryUnits[NB_HEAPS];
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/// All the allocated memory blocks
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MemoryBlock* mMemoryBlocks;
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/// Number of allocated memory blocks
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uint mNbAllocatedMemoryBlocks;
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/// Current number of used memory blocks
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uint mNbCurrentMemoryBlocks;
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#ifndef NDEBUG
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/// This variable is incremented by one when the allocate() method has been
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/// called and decreased by one when the release() method has been called.
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/// This variable is used in debug mode to check that the allocate() and release()
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/// methods are called the same number of times
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int mNbTimesAllocateMethodCalled;
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#endif
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public :
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// -------------------- Methods -------------------- //
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/// Constructor
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MemoryAllocator();
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/// Destructor
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~MemoryAllocator();
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/// Allocate memory of a given size (in bytes) and return a pointer to the
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/// allocated memory.
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void* allocate(size_t size);
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/// Release previously allocated memory.
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void release(void* pointer, size_t size);
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};
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}
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#endif
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