CopyBufferRegion

void CopyBufferRegion(
    ID3D12Resource  pDstBuffer,
    UINT64 DstOffset,
    ID3D12Resource  pSrcBuffer,
    UINT64 SrcOffset,
    UINT64 NumBytes
)

inline UINT64 UpdateSubresources(
_In_ ID3D12GraphicsCommandList* pCmdList,
_In_ ID3D12Resource* pDestinationResource,
_In_ ID3D12Resource* pIntermediate,
_In_range_(0,D3D12_REQ_SUBRESOURCES) UINT FirstSubresource,
_In_range_(0,D3D12_REQ_SUBRESOURCES-FirstSubresource) UINT NumSubresources,
UINT64 RequiredSize,
_In_reads_(NumSubresources) const D3D12_PLACED_SUBRESOURCE_FOOTPRINT* pLayouts,
_In_reads_(NumSubresources) const UINT* pNumRows,
_In_reads_(NumSubresources) const UINT64* pRowSizesInBytes,
_In_reads_(NumSubresources) const D3D12_SUBRESOURCE_DATA* pSrcData)
{
// Minor validation
D3D12_RESOURCE_DESC IntermediateDesc = pIntermediate->GetDesc();
D3D12_RESOURCE_DESC DestinationDesc = pDestinationResource->GetDesc();
if (IntermediateDesc.Dimension != D3D12_RESOURCE_DIMENSION_BUFFER ||
IntermediateDesc.Width < RequiredSize + pLayouts[0].Offset ||
RequiredSize > (SIZE_T)-1 ||
(DestinationDesc.Dimension == D3D12_RESOURCE_DIMENSION_BUFFER &&
(FirstSubresource != 0 || NumSubresources != 1)))
{
return 0;
}

BYTE* pData;
HRESULT hr = pIntermediate->Map(0, NULL, reinterpret_cast<void**>(&pData));
if (FAILED(hr))
{
return 0;
}

for (UINT i = 0; i < NumSubresources; ++i)
{
if (pRowSizesInBytes[i] > (SIZE_T)-1) return 0;
D3D12_MEMCPY_DEST DestData = { pData + pLayouts[i].Offset, pLayouts[i].Footprint.RowPitch, pLayouts[i].Footprint.RowPitch * pNumRows[i] };
MemcpySubresource(&DestData, &pSrcData[i], (SIZE_T)pRowSizesInBytes[i], pNumRows[i], pLayouts[i].Footprint.Depth);
}
pIntermediate->Unmap(0, NULL);

if (DestinationDesc.Dimension == D3D12_RESOURCE_DIMENSION_BUFFER)
{
CD3DX12_BOX SrcBox( UINT( pLayouts[0].Offset ), UINT( pLayouts[0].Offset + pLayouts[0].Footprint.Width ) );
pCmdList->CopyBufferRegion(
pDestinationResource, 0, pIntermediate, pLayouts[0].Offset, pLayouts[0].Footprint.Width);
}
else
{
for (UINT i = 0; i < NumSubresources; ++i)
{
CD3DX12_TEXTURE_COPY_LOCATION Dst(pDestinationResource, i + FirstSubresource);
CD3DX12_TEXTURE_COPY_LOCATION Src(pIntermediate, pLayouts[i]);
pCmdList->CopyTextureRegion(&Dst, 0, 0, 0, &Src, nullptr);
}
}
return RequiredSize;
}