Using nibbles in struct C#

Question

Can we work with nibbles in C# struct like C++?. Is there any equivalent code in C#?

typedef struct PHeader {
    #if defined(LITTLE_ENDIAN)
        uint8_t         mHdrLen  :4;
        uint8_t         mVer     :4;
    #elif defined (BIG_ENDIAN)
        uint8_t         mVer    :4;         
        uint8_t         mHdrLen :4;        
    #endif
     }

Thank You.

POssible dupe http://stackoverflow.com/questions/14464/bit-fields-in-c-sharp — Severin Pappadeux, Nov 23 '16 at 02:15

Niyoko · Accepted Answer · 2016-11-23T02:27:44.377

You can achieve same result using [StructLayout(LayoutKind.Explicit)] and FieldOffset attribute. You can read more about it here and here.

But please note that FieldOffset works in byte unit, not bit.

[StructLayout(LayoutKind.Explicit)]
struct X
{
#if A
    [FieldOffset(0)] public byte a;
    [FieldOffset(1)] public byte b;
#else
    [FieldOffset(0)] public byte b;
    [FieldOffset(1)] public byte a;
#endif
}

Example:

unsafe
{
    short x = 12300;
    X* y = (X*)&x;
    X t = *y;

    Console.WriteLine(t.a + " - " + t.b);
}

If you run that code with undefined A, you will get result 48 - 12 but if you #define A, then you will get result 12 - 48.

Using nibbles in struct C#

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