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[blok] / Box2D / Source / Common / b2StackAllocator.cpp

diff --git a/Box2D/Source/Common/b2StackAllocator.cpp b/Box2D/Source/Common/b2StackAllocator.cpp
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+++ b/Box2D/Source/Common/b2StackAllocator.cpp
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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.
+*/
+
+#include "b2StackAllocator.h"
+#include "b2Math.h"
+
+b2StackAllocator::b2StackAllocator()
+{
+       m_index = 0;
+       m_allocation = 0;
+       m_maxAllocation = 0;
+       m_entryCount = 0;
+}
+
+b2StackAllocator::~b2StackAllocator()
+{
+       b2Assert(m_index == 0);
+       b2Assert(m_entryCount == 0);
+}
+
+void* b2StackAllocator::Allocate(int32 size)
+{
+       b2Assert(m_entryCount < b2_maxStackEntries);
+
+       b2StackEntry* entry = m_entries + m_entryCount;
+       entry->size = size;
+       if (m_index + size > b2_stackSize)
+       {
+               entry->data = (char*)b2Alloc(size);
+               entry->usedMalloc = true;
+       }
+       else
+       {
+               entry->data = m_data + m_index;
+               entry->usedMalloc = false;
+               m_index += size;
+       }
+
+       m_allocation += size;
+       m_maxAllocation = b2Max(m_maxAllocation, m_allocation);
+       ++m_entryCount;
+
+       return entry->data;
+}
+
+void b2StackAllocator::Free(void* p)
+{
+       b2Assert(m_entryCount > 0);
+       b2StackEntry* entry = m_entries + m_entryCount - 1;
+       b2Assert(p == entry->data);
+       if (entry->usedMalloc)
+       {
+               b2Free(p);
+       }
+       else
+       {
+               m_index -= entry->size;
+       }
+       m_allocation -= entry->size;
+       --m_entryCount;
+
+       p = NULL;
+}
+
+int32 b2StackAllocator::GetMaxAllocation() const
+{
+       return m_maxAllocation;
+}