How to Pass Struct by Value?

Michael Ennen mike.ennen at gmail.com
Fri Oct 2 17:22:47 UTC 2020 

Okay, I will do that.

The code is at
https://github.com/brcolow/java-dx12/blob/master/src/main/java/com/dx12/DX12.java

On Fri, Oct 2, 2020 at 5:19 AM Jorn Vernee <jorn.vernee at oracle.com> wrote:

> Hi Michael,
>
> I'm not sure what value you are printing there, since you don't show the
> code.
>
> Presumably the ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart
> will fill in the 'ptr' field of the D3D12_CPU_DESCRIPTOR_HANDLE you pass it
> a pointer to, which is then used by ID3D12Device_CreateRenderTargetView.
> So, you could verify that the 'ptr' field is actually being set when
> calling ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart.
>
> Jorn
> On 02/10/2020 08:12, Michael Ennen wrote:
>
> One thing I noticed is that when I create pRtvHandle and print it, I get
> an address like so:
>
> pRtvHandlePtr: MemoryAddress{ base: null offset=0x1c655a6526f }
>
> The ptr struct member also seems to correspond to this number
>
> pRtvHandlePtr: 1951352115823 (converting to hex it is 0x1c655a6526f).
>
> But looking at the DirectX 12 debug errors I see:
>
> [17008] D3D12 ERROR: ID3D12Device::CreateRenderTargetView: Specified CPU
> descriptor handle ptr=0x000001C6D33B6210 does not refer to a location in a
> descriptor heap.  [ EXECUTION ERROR #646: INVALID_DESCRIPTOR_HANDLE]
>
> And thus I am not sure where it is getting that address from...maybe it's
> the address of the pointer itself and not the ptr struct member?
>
> But even so trying to do:
>
> ID3D12Device_CreateRenderTargetView.invokeExact(pDevice.address(),
> pSurface0.address(), MemoryAddress.NULL,
> MemoryAddress.ofLong(pRtvHandlePtr));
>
> yields an EXCEPTION_ACCESS_VIOLATION so I don't think that's right, either.
>
> On Wed, Sep 30, 2020 at 12:40 PM Michael Ennen <mike.ennen at gmail.com>
> wrote:
>
>> Sorry, that should have been:
>>
>> 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());
>> 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.$LAYOUT()));
>> ID3D12Device_CreateRenderTargetView.invokeExact(pDevice.address(),
>> pSurface0.address(), MemoryAddress.NULL, pRtvHandle);
>>
>> On Wed, Sep 30, 2020 at 12:38 PM Michael Ennen <mike.ennen at gmail.com>
>> wrote:
>>
>>> I tried using your example and adapting it to the following:
>>>
>>> var pRtvHandle = D3D12_CPU_DESCRIPTOR_HANDLE.allocate(scope);
>>> MethodHandle ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart =
>>> getInstance().downcallHandle(
>>> getCPUDescriptorHandleForHeapStartAddr,
>>> MethodType.methodType(void.class, MemoryAddress.class,
>>> MemorySegment.class),
>>> FunctionDescriptor.ofVoid(C_POINTER, C_POINTER));
>>> ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart.invokeExact(
>>> pHeapDescriptor.address(), pRtvHandle.address());
>>> MethodHandle ID3D12Device_CreateRenderTargetView =
>>> getInstance().downcallHandle(
>>> createRenderTargetViewAddr,
>>> MethodType.methodType(void.class, MemoryAddress.class,
>>> MemoryAddress.class, MemoryAddress.class, MemorySegment.class),
>>> FunctionDescriptor.ofVoid(C_POINTER, C_POINTER, C_POINTER,
>>> D3D12_CPU_DESCRIPTOR_HANDLE.$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
>>>> <https://urldefense.com/v3/__https://github.com/wolfgangfengel/graphicsdemoskeleton/blob/ba11402b6027ea14322bc430a23f2aadf3c0b11c/DirectX*2012/01_Skeleton/Window.c*L263__;JSM!!GqivPVa7Brio!I6BvzIBgWMA2lOJmtL2_8SkxW-f6kS61xDEp2QD_ymKDSTMczKYyQ9JYmgm4BTXB$>
>>>>
>>>> On Wed, Sep 30, 2020 at 11:45 AM Michael Ennen <mike.ennen at gmail.com>
>>>> wrote:
>>>>
>>>>> Ah yes I should have mentioned that this is actually an error with the
>>>>> unsupported DirectX 12 C API.
>>>>>
>>>>> See the following:
>>>>>
>>>>>             // Even though GetCPUDescriptorHandleForHeapStart is
>>>>> documented as taking no arguments (except for the
>>>>>             // this pointer), to use from C code it needs to take an
>>>>> additional rtvHandle argument, see, for example:
>>>>>             //
>>>>> https://joshstaiger.org/notes/C-Language-Problems-in-Direct3D-12-GetCPUDescriptorHandleForHeapStart.html
>>>>> <https://urldefense.com/v3/__https://joshstaiger.org/notes/C-Language-Problems-in-Direct3D-12-GetCPUDescriptorHandleForHeapStart.html__;!!GqivPVa7Brio!I6BvzIBgWMA2lOJmtL2_8SkxW-f6kS61xDEp2QD_ymKDSTMczKYyQ9JYmgVwkGCK$>
>>>>>             //
>>>>> https://github.com/curldivergence/dx12bindings/blob/841974943b7fbbd146d5372e9b496a9d72daf771/build.rs#L33
>>>>> <https://urldefense.com/v3/__https://github.com/curldivergence/dx12bindings/blob/841974943b7fbbd146d5372e9b496a9d72daf771/build.rs*L33__;Iw!!GqivPVa7Brio!I6BvzIBgWMA2lOJmtL2_8SkxW-f6kS61xDEp2QD_ymKDSTMczKYyQ9JYmnHkpAW0$>
>>>>>
>>>>> On Wed, Sep 30, 2020 at 2:55 AM Jorn Vernee <jorn.vernee at oracle.com>
>>>>> wrote:
>>>>>
>>>>>> Once again formatting is getting messed up.
>>>>>>
>>>>>> Uploaded a file here: http://cr.openjdk.java.net/~jvernee/ec.txt
>>>>>>
>>>>>> Jorn
>>>>>>
>>>>>> On 30/09/2020 11:47, Jorn Vernee wrote:
>>>>>> > Hi Micheal,
>>>>>> >
>>>>>> > When I look at the d3d12.h header, I only find this declaration of
>>>>>> > GetCPUDescriptorHandleForHeapStart:
>>>>>> >
>>>>>> >         D3D12_CPU_DESCRIPTOR_HANDLE ( STDMETHODCALLTYPE
>>>>>> > *GetCPUDescriptorHandleForHeapStart )(
>>>>>> >             ID3D12DescriptorHeap * This);
>>>>>> >
>>>>>> > Which is in ID3D12DescriptorHeapVtbl.
>>>>>> >
>>>>>> > The return type being defined as:
>>>>>> >
>>>>>> > typedef struct D3D12_CPU_DESCRIPTOR_HANDLE
>>>>>> >     {
>>>>>> >     SIZE_T ptr;
>>>>>> >     }     D3D12_CPU_DESCRIPTOR_HANDLE;
>>>>>> >
>>>>>> > I'd expect this to be linked and invoked as:
>>>>>> >
>>>>>> > MemorySegment heapDescriptorVtbl =
>>>>>> > asSegment(ID3D12DescriptorHeap.lpVtbl$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.$LAYOUT(),
>>>>>> > C_POINTER)); MemorySegment handle = (MemorySegment)
>>>>>> >
>>>>>> ID3D12DescriptorHeap_GetCPUDescriptorHandleForHeapStart.invokeExact(pHeapDescriptor.address());
>>>>>>
>>>>>> > // ^^^ don't forget to close this after using
>>>>>> >
>>>>>> > The linker will take care of handling all the ABI details.
>>>>>> >
>>>>>> > HTH,
>>>>>> > Jorn
>>>>>> >
>>>>>> > On 30/09/2020 08:36, Michael Ennen wrote:
>>>>>> >> I am messing around with DirectX 12 more and I am getting stuck on
>>>>>> >> how to
>>>>>> >> call the "GetCPUDescriptorHandleForHeapStart " method. It must
>>>>>> take a
>>>>>> >> struct by-value and not as a pointer reference.
>>>>>> >>
>>>>>> https://docs.microsoft.com/en-us/windows/win32/api/d3d12/nf-d3d12-id3d12descriptorheap-getcpudescriptorhandleforheapstart
>>>>>> <https://urldefense.com/v3/__https://docs.microsoft.com/en-us/windows/win32/api/d3d12/nf-d3d12-id3d12descriptorheap-getcpudescriptorhandleforheapstart__;!!GqivPVa7Brio!I6BvzIBgWMA2lOJmtL2_8SkxW-f6kS61xDEp2QD_ymKDSTMczKYyQ9JYmoVq3N9K$>
>>>>>> >>
>>>>>> >>
>>>>>> >> 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
>>>>>> <https://urldefense.com/v3/__https://github.com/halide/Halide/issues/5156__;!!GqivPVa7Brio!I6BvzIBgWMA2lOJmtL2_8SkxW-f6kS61xDEp2QD_ymKDSTMczKYyQ9JYmqVYKSkY$>
>>>>>> for example).
>>>>>> >>
>>>>>> >> I have the following:
>>>>>> >>
>>>>>> >> MemorySegment heapDescriptorVtbl =
>>>>>> >> asSegment(ID3D12DescriptorHeap.lpVtbl$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/
>>>>>> <https://urldefense.com/v3/__https://github.com/brcolow/java-dx12/__;!!GqivPVa7Brio!I6BvzIBgWMA2lOJmtL2_8SkxW-f6kS61xDEp2QD_ymKDSTMczKYyQ9JYmp0p5LUD$>
>>>>>> >>
>>>>>> >> Thanks very much.
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Michael Ennen
>>>>>
>>>>
>>>>
>>>> --
>>>> Michael Ennen
>>>>
>>>
>>>
>>> --
>>> Michael Ennen
>>>
>>
>>
>> --
>> Michael Ennen
>>
>
>
> --
> Michael Ennen
>
>

-- 
Michael Ennen

More information about the panama-dev mailing list