using System;

using System.Runtime.InteropServices;

​

namespace Test

{

    [StructLayout(LayoutKind.Sequential)]

    public struct SpellEffectDataDefault

    {

        public uint DataBits00;

        public uint DataBits01;

        public uint DataBits02;

        public uint DataBits03;

        public uint DataBits04;

        public uint DataBits05;

        public uint DataBits06;

        public uint DataBits07;

        public uint DataBits08;

        public uint DataBits09;

    }

​

    [StructLayout(LayoutKind.Sequential)]

    public struct SpellEffectDataUnitPropertyModifier

    {

        public uint Property;

        public uint Method;

        public float BaseValue;

        public float Modifier;

    }

​

    [StructLayout(LayoutKind.Sequential)]

    public struct SpellEffectDataProxy

    {

        public uint Spell4Id;

        public uint DataBits01;

        public uint DataBits02;

        public float DataBits03;

    }

​

    [StructLayout(LayoutKind.Sequential)]

    public struct SpellEffectDataDamage

    {

        public float Amount;

    }

​

    [StructLayout(LayoutKind.Explicit)]

    public struct SpellEffectDataUnion

    {

        [FieldOffset(0)]

        public SpellEffectDataDefault Default;

​

        [FieldOffset(0)]

        public SpellEffectDataUnitPropertyModifier UnitPropertyModifier;

​

        [FieldOffset(0)]

        public SpellEffectDataProxy Proxy;

​

        [FieldOffset(0)]

        public SpellEffectDataDamage Damage;

    }

​

    class Program

    {

        static void Main()

        {

            var data = new SpellEffectDataDefault

            {

                DataBits00 = 123,

                DataBits01 = 456,

                DataBits02 = 789

            };

​

            // pretend these bytes came from the tbl

            Span<SpellEffectDataDefault> dataSpan = MemoryMarshal.CreateSpan(ref data, 1);

            Span<byte> byteSpan = MemoryMarshal.Cast<SpellEffectDataDefault, byte>(dataSpan);

​

            SpellEffectDataUnion union = MemoryMarshal.Cast<byte, SpellEffectDataUnion>(byteSpan)[0];

            Console.WriteLine(union.Default.DataBits00);

            Console.WriteLine(union.UnitPropertyModifier.Property);

            Console.WriteLine(union.Proxy.Spell4Id);

            Console.WriteLine(union.Damage.Amount);

        }

    }

}

​