[DX12] Assign constant buffer and write its GPU address into descriptor heap

assgin_constant_buffer.cpp

void DeviceManDX12::AssignConstantBuffer(int descriptorHeapIndex, const void* buf, int size)
{
	int sizeAligned = (size + 0xff) & ~0xff;
	int numRequired = sizeAligned / 0x100;

	if (numAssignedConstantBufferBlocks + numRequired > maxConstantBufferBlocks) {
		assert(0);
		return;
	}
	int top = numAssignedConstantBufferBlocks;
	numAssignedConstantBufferBlocks += numRequired;

	memcpy(mappedConstantBuffer + top, buf, size);

	D3D12_CONSTANT_BUFFER_VIEW_DESC cbvDesc = {};
	cbvDesc.BufferLocation = constantBuffer->GetGPUVirtualAddress() + top * 0x100;
	cbvDesc.SizeInBytes = sizeAligned;
	assert((cbvDesc.SizeInBytes & 0xff) == 0);

	D3D12_CPU_DESCRIPTOR_HANDLE ptr = srvHeap->GetCPUDescriptorHandleForHeapStart();
	ptr.ptr += deviceMan.GetDevice()->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_CBV_SRV_UAV) * descriptorHeapIndex;
	deviceMan.GetDevice()->CreateConstantBufferView(&cbvDesc, ptr);
}