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[blok] / Box2D / Source / Common / b2BlockAllocator.h

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+/*
+* Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com
+*
+* 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 "b2Settings.h"
+
+const int32 b2_chunkSize = 4096;
+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 b2BlockAllocator
+{
+public:
+       b2BlockAllocator();
+       ~b2BlockAllocator();
+
+       void* Allocate(int32 size);
+       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