I had idea about message parsing in serial communication, there are many kind of packets which have different form. but they're all sent by byte array.
so I thought using union to parse each message. but it's not working well. following code is the sample code which I'm In Error
[StructLayout(LayoutKind.Explicit, Size=12)]
public struct UnionPacket
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst=12)]
public byte[] data;
[FieldOffset(0)]
public float Time;
[FieldOffset(4)]
public Int16 CoordX;
[FieldOffset(6)]
public Int16 CoordY;
[FieldOffset(8)]
public byte Red;
[FieldOffset(9)]
public byte Green;
[FieldOffset(10)]
public byte Blue;
[FieldOffset(11)]
public byte Alpha;
}
if this were possible, it would be very happy, but it isn't. This code occurs TypeLoadException "... because it contains an object field at offset 0 that is incorrectly aligned or overlapped by a non-object field."
So I changed some code like this
[StructLayout(LayoutKind.Explicit, Size= 12)]
public struct UnionPacket
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 12)]
[FieldOffset(0)]
public byte[] data;
//[FieldOffset(0)]
//public float Time;
[FieldOffset(4)]
public Int16 CoordX;
[FieldOffset(6)]
public Int16 CoordY;
[FieldOffset(8)]
public byte Red;
[FieldOffset(9)]
public byte Green;
[FieldOffset(10)]
public byte Blue;
[FieldOffset(11)]
public byte Alpha;
}
for test, i just disabled Time field which offset is 0, and this didn't occur Exception. but, if i change other fields, it doesn't change byte array. i think that byte array's real memory location is allocated in other heap, so it cannot be done.
Is there any way to solve this problem in C#? only C++ or C can solve this? and if i use this with inheritance, is it possible?
P.S. Sorry about my poor english