84 lines
2.1 KiB
C++
84 lines
2.1 KiB
C++
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#pragma once
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#include <cassert>
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#include <cstdlib>
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#include <cstring>
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#include <memory>
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#include <stdexcept>
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#include <vector>
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namespace clap { namespace helpers {
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/** Simple heap allocator which ensures alignment. */
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class Heap {
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public:
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explicit Heap(uint32_t initialSize = 4096) { reserve(initialSize); }
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~Heap() { std::free(_base); }
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Heap(const Heap &) = delete;
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Heap(Heap &&) = delete;
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Heap &operator=(const Heap &) = delete;
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Heap &operator=(Heap &&) = delete;
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void reserve(const size_t heapSize) {
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if (heapSize <= _size)
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return;
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auto *const ptr = static_cast<uint8_t *>(std::realloc(_base, heapSize));
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if (!ptr)
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throw std::bad_alloc();
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_base = ptr;
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_size = heapSize;
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}
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void clear() { _brk = 0; }
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void *tryAllocate(uint32_t align, uint32_t size) {
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assert(_brk <= _size);
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void *ptr = _base + _brk;
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size_t space = _size - _brk;
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if (!std::align(align, size, ptr, space))
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return nullptr;
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auto offset = static_cast<uint8_t *>(ptr) - _base;
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_brk = offset + size;
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std::memset(ptr, 0, size);
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return ptr;
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}
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void *allocate(uint32_t align, uint32_t size) {
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assert(_brk <= _size);
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if (size + _brk > _size)
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reserve(_size * 2);
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auto ptr = tryAllocate(align, size);
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assert(ptr);
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return ptr;
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}
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void *ptrFromBase(size_t offset) const {
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assert(offset <= _brk && "out of range");
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return static_cast<uint8_t *>(_base) + offset;
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}
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size_t offsetFromBase(const void *ptr) const {
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assert(ptr >= _base && "ptr before heap's base");
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size_t offset = static_cast<const uint8_t *>(ptr) - _base;
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assert(offset < _size && "ptr after heap's end");
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return offset;
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}
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size_t size() const { return _size; }
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bool empty() const { return _brk == 0; }
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private:
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size_t _size = 0;
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size_t _brk = 0;
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uint8_t *_base = nullptr;
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};
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}} // namespace clap::helpers
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