How to Pass Struct by Value?

[Michael Ennen]

I tried using your example and adapting it to the following:

var pRtvHandle = D3D12_CPU_DESCRIPTOR_HANDLE.allocate(scope);
MethodHandle ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart =
getInstance().downcallHandle(
getCPUDescriptorHandleForHeapStartAddr,
MethodType.methodType(void.class, MemoryAddress.class, MemorySegment.class),
FunctionDescriptor.ofVoid(C_POINTER, C_POINTER));
ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart.invokeExact(
pHeapDescriptor.address(), pRtvHandle.address());
MethodHandle ID3D12Device_CreateRenderTargetView =
getInstance().downcallHandle(
createRenderTargetViewAddr,
MethodType.methodType(void.class, MemoryAddress.class, MemoryAddress.class,
MemoryAddress.class, MemorySegment.class),
FunctionDescriptor.ofVoid(C_POINTER, C_POINTER, C_POINTER,
D3D12_CPU_DESCRIPTOR_HANDLE.$LAYOUT()));
ID3D12Device_CreateRenderTargetView.invokeExact(pDevice.address(),
pSurface0.address(), MemoryAddress.NULL, pRtvHandle);

But no dice.


On Wed, Sep 30, 2020 at 11:46 AM Michael Ennen <mike.ennen at gmail.com> wrote:

> See also:
>
>
> https://github.com/wolfgangfengel/graphicsdemoskeleton/blob/ba11402b6027ea14322bc430a23f2aadf3c0b11c/DirectX%2012/01_Skeleton/Window.c#L263
>
> On Wed, Sep 30, 2020 at 11:45 AM Michael Ennen <mike.ennen at gmail.com>
> wrote:
>
>> Ah yes I should have mentioned that this is actually an error with the
>> unsupported DirectX 12 C API.
>>
>> See the following:
>>
>>             // Even though GetCPUDescriptorHandleForHeapStart is
>> documented as taking no arguments (except for the
>>             // this pointer), to use from C code it needs to take an
>> additional rtvHandle argument, see, for example:
>>             //
>> https://joshstaiger.org/notes/C-Language-Problems-in-Direct3D-12-GetCPUDescriptorHandleForHeapStart.html
>>             //
>> https://github.com/curldivergence/dx12bindings/blob/841974943b7fbbd146d5372e9b496a9d72daf771/build.rs#L33
>>
>> On Wed, Sep 30, 2020 at 2:55 AM Jorn Vernee <jorn.vernee at oracle.com>
>> wrote:
>>
>>> Once again formatting is getting messed up.
>>>
>>> Uploaded a file here: http://cr.openjdk.java.net/~jvernee/ec.txt
>>>
>>> Jorn
>>>
>>> On 30/09/2020 11:47, Jorn Vernee wrote:
>>> > Hi Micheal,
>>> >
>>> > When I look at the d3d12.h header, I only find this declaration of
>>> > GetCPUDescriptorHandleForHeapStart:
>>> >
>>> >         D3D12_CPU_DESCRIPTOR_HANDLE ( STDMETHODCALLTYPE
>>> > *GetCPUDescriptorHandleForHeapStart )(
>>> >             ID3D12DescriptorHeap * This);
>>> >
>>> > Which is in ID3D12DescriptorHeapVtbl.
>>> >
>>> > The return type being defined as:
>>> >
>>> > typedef struct D3D12_CPU_DESCRIPTOR_HANDLE
>>> >     {
>>> >     SIZE_T ptr;
>>> >     }     D3D12_CPU_DESCRIPTOR_HANDLE;
>>> >
>>> > I'd expect this to be linked and invoked as:
>>> >
>>> > MemorySegment heapDescriptorVtbl =
>>> > asSegment(ID3D12DescriptorHeap.lpVtbl$get(pHeapDescriptor),
>>> > ID3D12DescriptorHeapVtbl.$LAYOUT()); MemoryAddress
>>> > getCPUDescriptorHandleForHeapStartAddr =
>>> >
>>> ID3D12DescriptorHeapVtbl.GetCPUDescriptorHandleForHeapStart$get(heapDescriptorVtbl);
>>>
>>> > MethodHandle ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart =
>>> > getInstance().downcallHandle(getCPUDescriptorHandleForHeapStartAddr,
>>> > MethodType.methodType(MemorySegment.class, MemoryAddress.class),
>>> > FunctionDescriptor.of(D3D12_CPU_DESCRIPTOR_HANDLE.$LAYOUT(),
>>> > C_POINTER)); MemorySegment handle = (MemorySegment)
>>> >
>>> ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart.invokeExact(pHeapDescriptor.address());
>>>
>>> > // ^^^ don't forget to close this after using
>>> >
>>> > The linker will take care of handling all the ABI details.
>>> >
>>> > HTH,
>>> > Jorn
>>> >
>>> > On 30/09/2020 08:36, Michael Ennen wrote:
>>> >> I am messing around with DirectX 12 more and I am getting stuck on
>>> >> how to
>>> >> call the "GetCPUDescriptorHandleForHeapStart " method. It must take a
>>> >> struct by-value and not as a pointer reference.
>>> >>
>>> https://docs.microsoft.com/en-us/windows/win32/api/d3d12/nf-d3d12-id3d12descriptorheap-getcpudescriptorhandleforheapstart
>>> >>
>>> >>
>>> >> There seems to be a bit of an issue with that method as I see some
>>> >> Github
>>> >> issues talking about it's weird ABI, but I don't think I am hitting
>>> that
>>> >> issue (see https://github.com/halide/Halide/issues/5156 for example).
>>> >>
>>> >> I have the following:
>>> >>
>>> >> MemorySegment heapDescriptorVtbl =
>>> >> asSegment(ID3D12DescriptorHeap.lpVtbl$get(pHeapDescriptor),
>>> >> ID3D12DescriptorHeapVtbl.$LAYOUT());
>>> >> MemoryAddress getCPUDescriptorHandleForHeapStartAddr =
>>> >>
>>> ID3D12DescriptorHeapVtbl.GetCPUDescriptorHandleForHeapStart$get(heapDescriptorVtbl);
>>>
>>> >>
>>> >> var pRtvHandle = D3D12_CPU_DESCRIPTOR_HANDLE.allocate(scope);
>>> >> MethodHandle ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart =
>>> >> getInstance().downcallHandle(getCPUDescriptorHandleForHeapStartAddr,
>>> >> MethodType.methodType(void.class, MemoryAddress.class,
>>> >> MemoryAddress.class),
>>> >> FunctionDescriptor.ofVoid(C_POINTER, C_POINTER));
>>> >> ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart.invokeExact(
>>> >> pHeapDescriptor.address(), pRtvHandle.address());
>>> >>
>>> >> But it is not right as I am passing in D3D12_CPU_DESCRIPTOR_HANDLE as
>>> a
>>> >> pointer.
>>> >>
>>> >> I tried exploring the Panama API and looking at tests but just didn't
>>> >> find
>>> >> what I was looking for (how to pass a struct by value, if that's
>>> >> possible
>>> >> with the ABI semantics).
>>> >>
>>> >> My current work is here:
>>> >>
>>> >> https://github.com/brcolow/java-dx12/
>>> >>
>>> >> Thanks very much.
>>>
>>
>>
>> --
>> Michael Ennen
>>
>
>
> --
> Michael Ennen
>


-- 
Michael Ennen