69 lines
1.4 KiB
C++
69 lines
1.4 KiB
C++
# pragma once
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template<size_t ChunkSize>
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class PoolAllocator
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{
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struct Page
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{
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char memory[4096];
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};
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union Node
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{
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Node *previous;
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char chunk[ChunkSize];
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};
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public:
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PoolAllocator()
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{
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}
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~PoolAllocator()
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{
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dispose();
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}
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void *allocate(size_t size)
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{
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Q_ASSERT(size <= ChunkSize);
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if (!stack && !grow())
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return nullptr;
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Node *top = stack;
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stack = stack->previous;
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return top->chunk;
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}
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void free(void *ptr)
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{
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Node *top = static_cast<Node*>(ptr);
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top->previous = stack;
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stack = top;
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}
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void dispose() {
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for (auto page : pages)
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::free(page);
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pages.clear();
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stack = nullptr;
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}
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private:
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bool grow()
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{
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Page *newPage = static_cast<Page*>(::malloc(sizeof(Page)));
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if (!newPage)
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return false;
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initPage(newPage);
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pages.append(newPage);
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return true;
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}
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void initPage(Page *page)
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{
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Node *newStack = reinterpret_cast<Node*>(page->memory);
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newStack->previous = stack;
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const size_t numChunks = sizeof(Page) / sizeof(Node);
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for (size_t i = 0; i < numChunks - 1; ++i, ++newStack)
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newStack[1].previous = newStack;
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stack = newStack;
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}
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Node *stack = nullptr;
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QVector<Page*> pages;
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}; |