how to call a C# function, foo(out byte [])? -- help passing a byte pointer
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daniel rasnow
le 5 Juin 2014
Commenté : daniel rasnow
le 28 Juil 2014
Been struggling to call the following function in a C# dll:
public bool GetLatestBuffer(out byte[] buffer)
I've allocated the buffer in Matlab and tried various castings with libpointer, but keep getting the result:
No method 'GetLatestBuffer' with matching signature found for class ...
I could write a wrapper in C# that allocates the buffer ... but would rather do the memory management in Matlab.
My pseudocode is basically:
NET.addAssembly(dllLoc)
ls = luma_ns.Luma(initParams);
ls.function1(params) % --> it works passing parameters by value
buf = zeros(10000,'uint8'); % tried uint16, int16, etc.
pbuf = libpointer('uint8Ptr',buf);
ls.GetLatestBuffer(pbuf) % doesn't match the prototype of out byte []
No method 'GetLatestBuffer' with matching signature found for class 'Luma_ns.Luma'.
Thanks!!
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Friedrich
le 21 Juil 2014
Modifié(e) : Friedrich
le 22 Juil 2014
Hi,
have you tried calling it like this
[bool_val, byte_array] = obj.GetLatestBuffer();
This works fine for me in 14a with the following example
C#
public bool GetLatestBuffer(out byte[] Buffer)
{
Buffer = new byte[10];
for (int i = 0; i < 10;i++)
{
Buffer[i] = (byte)i;
}
return true;
}
ML:
>> a = ClassLibrary1.Class1
a =
Class1 with no properties.
>> [bool,array] = a.GetLatestBuffer()
bool =
1
array =
Byte[] with properties:
Length: 10
LongLength: 10
Rank: 1
SyncRoot: [1x1 System.Byte[]]
IsReadOnly: 0
IsFixedSize: 1
IsSynchronized: 0
>>
SideNote: The out keyword forces the routine GetLatestBuffer to assign Buffer to some value. So you do NOT need to pass down a preallocated array and since you dont need to do this it appears as output in MATLAB directly.
Also in C# when using OUT you never pass down a preallocated array. So what MATLAB does is correct here and matches the .NET programming.
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James Tursa
le 5 Juin 2014
Have you tried changing the header signature to something more friendly to MATLAB, but have the same basic I/O? E.g.,
bool GetLatestBuffer(char *buffer);
3 commentaires
James Tursa
le 6 Juin 2014
Don't recompile. Just create a new header file off to the side for MATLAB to use. I.e., copy the actual header h file to a new file, modify that new file by changing the signature of the function in question, then use that new header h file for calllib in MATLAB.
Friedrich
le 22 Juil 2014
This wont work because that is the .NET interface he is using and not loadlibrary!!!!
Anthony
le 17 Juil 2014
Hi,
You can create a byte[] like this:
A = NET.createArray('System.Byte',4).
Then you just have to pass it to your function.
Hope it helps,
Anthony
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