Time zone converter for Unity (Windows)

TimeZoneDatabase.cs

using System.Collections.Generic;
using Microsoft.Win32;
using System.Runtime.InteropServices;
using System;
using System.Text;

namespace WorldClock {
	public static class TimeZoneDatabase {
		public const string KERNEL32 = "kernel32.dll";
		public const string REGISTRY = @"SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones";

		public static readonly Dictionary<string, TIME_ZONE_INFORMATION> TIME_ZONES 
			= new Dictionary<string, TIME_ZONE_INFORMATION>();

		static TimeZoneDatabase() {
			using (RegistryKey key = Registry.LocalMachine.OpenSubKey(REGISTRY)) {
				foreach (string zoneName in key.GetSubKeyNames()) {
					using (RegistryKey subKey = key.OpenSubKey(zoneName)) {
						//var displayName =(string)subKey.GetValue("Display");
						var info = TIME_ZONE_INFORMATION.Generate(
							(string)subKey.GetValue("Std"),
							(string)subKey.GetValue("Dlt"),
							(TZI)((byte[])subKey.GetValue("Tzi")));
						TIME_ZONES.Add(zoneName, info);
					}
				}
			}
		}

		[StructLayout(LayoutKind.Sequential)]
		public struct SYSTEMTIME {
			public UInt16 wYear;
			public UInt16 wMonth;
			public UInt16 wDayOfWeek;
			public UInt16 wDay;
			public UInt16 wHour;
			public UInt16 wMinute;
			public UInt16 wSecond;
			public UInt16 wMilliseconds;

			public static implicit operator SYSTEMTIME(DateTime dt) {
				return new SYSTEMTIME(){
					wYear = Convert.ToUInt16(dt.Year),
					wMonth = Convert.ToUInt16(dt.Month),
					wDayOfWeek = Convert.ToUInt16(dt.DayOfWeek),
					wDay = Convert.ToUInt16(dt.Day),
					wHour = Convert.ToUInt16(dt.Hour),
					wMinute = Convert.ToUInt16(dt.Minute),
					wSecond = Convert.ToUInt16(dt.Second),
					wMilliseconds = Convert.ToUInt16(dt.Millisecond)
				};
			}
			public static implicit operator DateTime(SYSTEMTIME st) {
				return new DateTime(st.wYear, st.wMonth, st.wDay, st.wHour, st.wMinute, st.wSecond, st.wMilliseconds, 
				                    DateTimeKind.Unspecified);
			}
		}

		[StructLayout(LayoutKind.Sequential)]
		public struct TZI {
			public int bias;
			public int standardBias;
			public int daylightBias;
			public SYSTEMTIME standardDate;
			public SYSTEMTIME daylightDate;

			public static implicit operator TZI(byte[] binaryTzi) {
				if (binaryTzi.Length != Marshal.SizeOf(typeof(TZI)))
					throw new ArgumentException("TZI size is incorrect", "binaryTzi");
				TZI tzi;
				var h = GCHandle.Alloc(binaryTzi, GCHandleType.Pinned);
				try {
					tzi = (TZI)Marshal.PtrToStructure(h.AddrOfPinnedObject(), typeof(TZI));
				} finally {
					h.Free();
				}
				return tzi;
			}
		}
		
		[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
		public struct TIME_ZONE_INFORMATION	{
			[MarshalAs(UnmanagedType.I4)]
			public Int32 Bias;
			[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
			public string StandardName;
			public SYSTEMTIME StandardDate;
			[MarshalAs(UnmanagedType.I4)]
			public Int32 StandardBias;
			[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
			public string DaylightName;
			public SYSTEMTIME DaylightDate;
			[MarshalAs(UnmanagedType.I4)]
			public Int32 DaylightBias;

			public static TIME_ZONE_INFORMATION Generate(string StandardName, string DaylightName, TZI tzi) {
				return new TIME_ZONE_INFORMATION() {
					StandardName = StandardName, DaylightName = DaylightName,
					Bias = tzi.bias, StandardBias = tzi.standardBias, DaylightBias = tzi.daylightBias,
					StandardDate = tzi.standardDate, DaylightDate = tzi.daylightDate
				};
			}

			public DateTime Universal2Local(DateTime utf) {
				var st = (SYSTEMTIME)utf;
				SYSTEMTIME local;
				SystemTimeToTzSpecificLocalTime(ref this, ref st, out local);
				return (DateTime)local;
			}
			public DateTime Local2Universal(DateTime local) {
				var st = (SYSTEMTIME)local;
				SYSTEMTIME utf;
				TzSpecificLocalTimeToSystemTime(ref this, ref st, out utf);
				return utf;
			}
		}
		
		[DllImport(KERNEL32)]
		public static extern uint GetTimeZoneInformation(out TIME_ZONE_INFORMATION lpTimeZoneInformation);
		
		[DllImport(KERNEL32)]
		public static extern bool SystemTimeToTzSpecificLocalTime(
			[In] ref TIME_ZONE_INFORMATION lpTimeZone,
			[In] ref SYSTEMTIME lpUniversalTime,
			out SYSTEMTIME lpLocalTime);

		[DllImport(KERNEL32)]
		public static extern bool TzSpecificLocalTimeToSystemTime(
			[In] ref TIME_ZONE_INFORMATION lpTimeZone,
			[In] ref SYSTEMTIME lpLocalTime,
			out SYSTEMTIME lpUniversalTime);
	}
}

/* References
 - Convert local time to Timezone. https://staceyw1.wordpress.com/2006/08/31/convert-local-time-to-timezone/
*/