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Lib/Include/Box2D/Common/b2BlockAllocator.h

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+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+*
+* This software is provided 'as-is', without any express or implied
+* warranty.  In no event will the authors be held liable for any damages
+* arising from the use of this software.
+* Permission is granted to anyone to use this software for any purpose,
+* including commercial applications, and to alter it and redistribute it
+* freely, subject to the following restrictions:
+* 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.
+* 2. Altered source versions must be plainly marked as such, and must not be
+* misrepresented as being the original software.
+* 3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef B2_BLOCK_ALLOCATOR_H
+#define B2_BLOCK_ALLOCATOR_H
+
+#include <Box2D/Common/b2Settings.h>
+
+const int32 b2_chunkSize = 16 * 1024;
+const int32 b2_maxBlockSize = 640;
+const int32 b2_blockSizes = 14;
+const int32 b2_chunkArrayIncrement = 128;
+
+struct b2Block;
+struct b2Chunk;
+
+/// This is a small object allocator used for allocating small
+/// objects that persist for more than one time step.
+/// See: http://www.codeproject.com/useritems/Small_Block_Allocator.asp
+class BOX2D_API b2BlockAllocator
+{
+public:
+	b2BlockAllocator();
+	~b2BlockAllocator();
+
+	/// Allocate memory. This will use b2Alloc if the size is larger than b2_maxBlockSize.
+	void* Allocate(int32 size);
+
+	/// Free memory. This will use b2Free if the size is larger than b2_maxBlockSize.
+	void Free(void* p, int32 size);
+
+	void Clear();
+
+private:
+
+	b2Chunk* m_chunks;
+	int32 m_chunkCount;
+	int32 m_chunkSpace;
+
+	b2Block* m_freeLists[b2_blockSizes];
+
+	static int32 s_blockSizes[b2_blockSizes];
+	static uint8 s_blockSizeLookup[b2_maxBlockSize + 1];
+	static bool s_blockSizeLookupInitialized;
+};
+
+#endif