I cracked the nut late last night. The problem was indeed on the C# side.
By forcing it to use "unsafe" code, I was able to define the struct in a C
native way and avoid .NET marshaling between it. I'm now getting exactly
what I expect in the file according to H5dump. Next step is an array of
200 of these. Then an ever expanding array of those arrays, and I'll have
my HDF5 data structure figured out. Thanks for your inputs!
Here is the solution:
[StructLayoutAttribute(LayoutKind.Sequential, Pack = 1)]
unsafe struct cStyleMessage
{
public uint MsgID;
public ulong MsgHWTimestamp;
public uint MsgLenthBytes;
public fixed byte MsgBody[8];
}
private void btn_WriteCustomType_Click(object sender,
RoutedEventArgs e)
{
//Create a C friendly struct full of easily walkable data...
cStyleMessage myCStyleMsg = new cStyleMessage();
myCStyleMsg.MsgID = 0x04030201; //dec: 67305985
myCStyleMsg.MsgHWTimestamp = 0x0C0B0A0908070605; //dec:
867798387104613893
myCStyleMsg.MsgLenthBytes = 0x100F0E0D; //dec: 269422093
unsafe
{
for (int i = 0; i < 8; i++)
{
myCStyleMsg.MsgBody[i] = (byte)(0x11 + i);
}
}
//Define HDF5 compound type
H5DataSpaceId myDataSpace = H5S.create(H5S.H5SClass.SCALAR);
int structSize = Marshal.SizeOf(myCStyleMsg);
H5DataTypeId myH5MessageType =
H5T.create(H5T.CreateClass.COMPOUND, structSize);
H5T.insert(myH5MessageType, "MsgID",0, new
H5DataTypeId(H5T.H5Type.STD_U32LE));
H5T.insert(myH5MessageType, "MsgHWTimestamp",4, new
H5DataTypeId(H5T.H5Type.STD_U64LE));
H5T.insert(myH5MessageType, "MsgLengthBytes", 12, new
H5DataTypeId(H5T.H5Type.STD_U32LE));
H5T.insert(myH5MessageType, "MsgBody", 16, H5T.create_array(new
H5DataTypeId(H5T.H5Type.STD_U8LE), new long[1] {8}));
//Create the compound type
H5DataSetId myDataSet = H5D.create(h5FileHandle,
"/myCustomData", myH5MessageType, myDataSpace);
//Write to file
H5D.writeScalar<cStyleMessage>(myDataSet, myH5MessageType, ref
myCStyleMsg);
//clean up localy created overhead
H5D.close(myDataSet);
H5S.close(myDataSpace);
}
Best regards,
Petr Klapka
System Tools Engineer
*Valeo* Radar Systems
46 River Rd
Hudson, NH 03051
Mobile: (603) 921-4440
Office: (603) 578-8045
*"Festina lente."*
On Fri, Aug 7, 2015 at 7:29 AM, Francesc Alted <[email protected]> wrote:
> 2015-08-06 22:20 GMT+02:00 Petr KLAPKA <[email protected]>:
>
>> Hello folks,
>>
>> I've been beating my head against this one all day... All I'm trying to
>> do is write a simple struct to a dataset. Using C# and the .NET wrapper,
>> if I remove the array from the struct, all is well, but once I introduce
>> the array, the data in the file is mangled (as shown). Any clues? Also,
>> is there a way to get h5dump to output the values in hex? I found nothing
>> in the documentation and it would be super useful for debugging. Thanks in
>> advance!
>>
>> [StructLayoutAttribute(LayoutKind.Sequential, Pack = 1)]
>> struct cStyleMessage
>> {
>> public uint MsgID;
>> public ulong MsgHWTimestamp;
>> public uint MsgLenthBytes;
>> [MarshalAs(UnmanagedType.ByValArray,
>> ArraySubType=UnmanagedType.U1, SizeConst=8)]
>> public byte[] MsgBody;
>> }
>>
>
> I am not a Windows person, so don't know how the MSC# is dealing with the
> alignment of structures, but I would try:
>
> struct cStyleMessage
> {
> public uint MsgID;
> public uint MsgLenthBytes;
> public ulong MsgHWTimestamp;
> [keep the rest the same]
> }
>
> If that does not help, then my advice is to start with a compound type of
> a single field, see if that works, and then proceed with 2 fields. When
> you reach this point you will be able to figure out how to generalize more
> easily.
>
> --
> Francesc Alted
>
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