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[blok] / Box2D / Source / Common / b2StackAllocator.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_STACK_ALLOCATOR_H
+#define B2_STACK_ALLOCATOR_H
+
+#include "b2Settings.h"
+
+const int32 b2_stackSize = 100 * 1024; // 100k
+const int32 b2_maxStackEntries = 32;
+
+struct b2StackEntry
+{
+       char* data;
+       int32 size;
+       bool usedMalloc;
+};
+
+// This is a stack allocator used for fast per step allocations.
+// You must nest allocate/free pairs. The code will assert
+// if you try to interleave multiple allocate/free pairs.
+class b2StackAllocator
+{
+public:
+       b2StackAllocator();
+       ~b2StackAllocator();
+
+       void* Allocate(int32 size);
+       void Free(void* p);
+
+       int32 GetMaxAllocation() const;
+
+private:
+
+       char m_data[b2_stackSize];
+       int32 m_index;
+
+       int32 m_allocation;
+       int32 m_maxAllocation;
+
+       b2StackEntry m_entries[b2_maxStackEntries];
+       int32 m_entryCount;
+};
+
+#endif