C# StructLayout Pack get System.NullReferenceException, alignement issue?

问题

First of all, I would say that, I'm not stuck, as there is a lot of workaround for me !! The best of then is that I don't need 1Byte Pack anymore :P

But honestly, I'm quite puzzle about the behavior. I'm using Unity, It works perfectly on Windows but failed on Android(mono)

Have I write something invalid ?
Do I have rise a bug on Mono ?!

Comments are definitivly welcome !!

public class TEST
{
    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    private struct MyStruct {
        public float   field1;
        public float   field2;
    };

    //This order sucess on windows, but failed on android
    private byte oneByte = 0x00;
    private MyStruct mMyStruct;


    public bool doTest()
    {
        try {
            mMyStruct.field1  = (oneByte++);
        } catch {
            // System.NullReferenceException: Object reference not set to an instance of an object
            return false;
        }
        return true;
    }           
}

Some extras infos/clues:

Difference between Android/Windows probably comes from processor architecture difference Android ARM(RISC), suppose 4Bytes alignement (or at least 2Bytes in thumb mode)
[StructLayout(LayoutKind.Sequential, Pack = 1)] seems to affect more than the struct.

Memory alignment probably becomes:

[ onByte    ]  [ field1 #0 ] [ field1 #1 ] [ field1 #2 ]
[ field1 #3 ]  [ field2 #1 ] [ field2 #1 ] [ field2 #3 ]
[ field2 #4 ]  [ *pad*     ] [ *pad*     ] [ *pad*     ]

Where I was expected more something like this:

[ onByte    ] [ *pad*     ] [ *pad*     ] [ *pad*     ]
[ field1 #0 ] [ field1 #1 ] [ field1 #2 ] [ field1 #3 ]
[ field2 #1 ] [ field2 #1 ] [ field2 #3 ][ field2 #4 ]

来源：https://stackoverflow.com/questions/22252819/c-sharp-structlayout-pack-get-system-nullreferenceexception-alignement-issue

标签

mono

unity3d

structlayout