C#でstructをバイト配列に変換する拡張メソッド ref: http://qiita.com/yu_ka1984/items/969728290b05e15f07a9

file0.cs

public static byte[] ToByteArray<T>(this T structure) where T : struct
{
    byte[] bb = new byte[Marshal.SizeOf(typeof(T))];
    GCHandle gch = GCHandle.Alloc(bb, GCHandleType.Pinned);
    Marshal.StructureToPtr(structure, gch.AddrOfPinnedObject(), false);
    gch.Free();
    return bb;
}