*

LEngine/D3d12DescriptorHeapAllocator.h

@@ -0,0 +1,83 @@
+#ifndef D3d12DescriptorHeap_h__
+#define D3d12DescriptorHeap_h__
+
+#include <d3d12.h>
+#include "d3d11_helper.h"
+#include "FatalError.h"
+#include <vector>
+#include "ForwardListItem.h"
+#include <wrl.h>
+
+using namespace Microsoft::WRL;
+
+class D3d12DescriptorHeapAllocator {
+public:
+	//Assuming that heap is EMPTY!
+	D3d12DescriptorHeapAllocator(ComPtr<ID3D12DescriptorHeap> heap):_heap(heap)
+	{
+		_descriptor = heap->GetDesc();
+		_heapStartAddress = heap->GetCPUDescriptorHandleForHeapStart().ptr;
+		ID3D12DevicePtr device;
+		heap->GetDevice(IID_PPV_ARGS(&device));
+		_itemSize = device->GetDescriptorHandleIncrementSize(_descriptor.Type);
+
+		_items.resize(_descriptor.NumDescriptors);
+		//init free items list 
+		for(size_t i = 0; i < _descriptor.NumDescriptors - 1; ++i){
+			_items[i].next = &_items[i + 1];
+		}
+		_items[_descriptor.NumDescriptors - 1].next = nullptr;
+		_listHead = &_items[0];
+	}
+
+	D3D12_CPU_DESCRIPTOR_HANDLE alloc(){
+		if(_listHead == nullptr){
+			return {0};
+		}
+		auto allocatedId = getItemIndex(_listHead);
+		auto resultAddress = _heapStartAddress + (allocatedId * _itemSize);
+		_listHead = _listHead->next;
+		return{ resultAddress };
+	}
+	void free(D3D12_CPU_DESCRIPTOR_HANDLE handle){
+		auto itemId = getDescriptorId(handle);
+		if (itemId >= _items.size()) {
+			throw std::exception("Invalid handle");
+		}
+		auto freeItem = &_items[itemId];
+		freeItem->next = _listHead;
+		_listHead = freeItem;
+
+	}
+	ComPtr<ID3D12DescriptorHeap> getHeap()
+	{
+		return _heap;
+	}
+	size_t getItemSize() const
+	{
+		return _itemSize;
+	}
+	size_t getDescriptorId(D3D12_CPU_DESCRIPTOR_HANDLE handle) const
+	{
+		if (handle.ptr < _heapStartAddress) {
+			throw std::exception("Invalid handle");
+		}
+		return (handle.ptr - _heapStartAddress) / _itemSize;
+	}
+	size_t getDescriptorsCount() const
+	{
+		return _descriptor.NumDescriptors;
+	}
+private:
+	size_t getItemIndex(const ForwardListItem* item) const noexcept{
+		return (item - &_items[0]);
+	}
+	ComPtr<ID3D12DescriptorHeap> _heap;
+	ForwardListItem* _listHead = nullptr;
+	std::vector<ForwardListItem> _items;
+	D3D12_DESCRIPTOR_HEAP_DESC _descriptor;
+	size_t _itemSize;
+	size_t _heapStartAddress;
+};
+
+#endif // D3d12DescriptorHeap_h__