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| ** |
| ** Copyright (C) 2008-2012 NVIDIA Corporation. |
| ** Copyright (C) 2019 The Qt Company Ltd. |
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| ** This file is part of Qt Quick 3D. |
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| |
| |
| #ifndef QSSGPERFRAMEALLOCATOR_H |
| #define QSSGPERFRAMEALLOCATOR_H |
| |
| // |
| // W A R N I N G |
| // ------------- |
| // |
| // This file is not part of the Qt API. It exists purely as an |
| // implementation detail. This header file may change from version to |
| // version without notice, or even be removed. |
| // |
| // We mean it. |
| // |
| |
| #include <QtQuick3DRuntimeRender/private/qtquick3druntimerenderglobal_p.h> |
| |
| QT_BEGIN_NAMESPACE |
| |
| class QSSGPerFrameAllocator |
| { |
| struct FastAllocator |
| { |
| struct Slab; |
| |
| enum : size_t { |
| ChunkSize = 8192*2, |
| Alignment = 4, |
| SlabSize = ChunkSize - sizeof(Slab *), |
| MaxAlloc = ChunkSize/2 // don't go all the way up to SlabSize, or we'd almost always get a big hole |
| }; |
| struct Slab { |
| Slab() = default; |
| Slab(Slab *previous) |
| { |
| previous->next = this; |
| } |
| Slab *next = nullptr; |
| quint8 data[SlabSize]; |
| }; |
| Q_STATIC_ASSERT(sizeof(Slab) == ChunkSize); |
| |
| Slab *first = nullptr; |
| Slab *current = nullptr; |
| size_t offset = 0; |
| |
| FastAllocator() |
| { |
| first = current = new Slab; |
| } |
| |
| ~FastAllocator() |
| { |
| Slab *s = first; |
| while (s) { |
| Slab *n = s->next; |
| delete s; |
| s = n; |
| } |
| } |
| void *allocate(size_t size) |
| { |
| size = (size + Alignment - 1) & ~(Alignment - 1); |
| Q_ASSERT(size <= SlabSize); |
| Q_ASSERT(!(offset % Alignment)); |
| |
| size_t amountLeftInSlab = SlabSize - offset; |
| if (size > amountLeftInSlab) { |
| if (current->next) |
| current = current->next; |
| else |
| current = new Slab(current); |
| offset = 0; |
| } |
| |
| quint8 *data = current->data + offset; |
| offset += size; |
| return data; |
| } |
| |
| // only reset, so we can re-use the memory |
| void reset() { current = first; offset = 0; } |
| }; |
| |
| struct LargeAllocator |
| { |
| struct Slab { |
| Slab *next = nullptr; |
| }; |
| Slab *current = nullptr; |
| |
| LargeAllocator() {} |
| |
| // Automatically deallocates everything that hasn't already been deallocated. |
| ~LargeAllocator() { deallocateAll(); } |
| |
| void deallocateAll() |
| { |
| while (current) { |
| Slab *n = current->next; |
| ::free(current); |
| current = n; |
| } |
| current = nullptr; |
| } |
| |
| void *allocate(size_t size) |
| { |
| quint8 *mem = reinterpret_cast<quint8 *>(::malloc(sizeof(Slab) + size)); |
| Slab *s = reinterpret_cast<Slab *>(mem); |
| s->next = current; |
| current = s; |
| return mem + sizeof(Slab); |
| } |
| }; |
| |
| FastAllocator m_fastAllocator; |
| LargeAllocator m_largeAllocator; |
| |
| public: |
| QSSGPerFrameAllocator() {} |
| |
| inline void *allocate(size_t size) |
| { |
| if (size < FastAllocator::MaxAlloc) |
| return m_fastAllocator.allocate(size); |
| else |
| return m_largeAllocator.allocate(size); |
| } |
| |
| void reset() |
| { |
| m_fastAllocator.reset(); |
| m_largeAllocator.deallocateAll(); |
| } |
| }; |
| |
| QT_END_NAMESPACE |
| |
| #endif // QSSGPERFRAMEALLOCATOR_H |