// ----------------------------------------------------------------------------
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ----------------------------------------------------------------------------

#define LITTLE_ENDIAN

using System;

namespace Smb.Shared
{
	/// <summary>
	/// <para>
	/// This class provides static methods for swapping byte order.
	/// You might think this was overkill for such a simple purpose -- why not just have two methods?
	/// The reason for providing so many methods is to allow developers to document what they are doing
	/// by choosing an appropriate method.  "x = HostToBe(y)" clearly shows that y is in big-endian,
	/// and is being converted to host order.
	/// </para>
	///
	/// <para>
	/// I have avoided the traditional terminology of "host order" vs "network order", and instead have
	/// used "host order", "big endian" (Be), and "little endian" (Le).  This is because not all network
	/// protocols use big-endian order.  The TCP/IP family does, but many others do not, especially those
	/// involving Microsoft products, such as SMB.
	/// </para>
	/// </summary>
	/*static*/ sealed class ByteOrder
	{
		private ByteOrder() {}
		
		public static ushort Swap(ushort value)
		{
			return unchecked((ushort)((value >> 8) | (value << 8)));
		}
		
		public static short Swap(short value)
		{
			ushort uvalue = unchecked((ushort)value);
			return unchecked((short)((uvalue >> 8) | (uvalue << 8)));
		}
		
		public static uint Swap(uint value)
		{
			return ((value & 0xff000000u) >> 24)
			| ((value & 0x00ff0000u) >> 8)
			| ((value & 0x0000ff00u) << 8)
			| ((value & 0x000000ffu) << 24);
		}
		
		public static int Swap(int value)
		{
			return unchecked((int)Swap((uint)value));
		}
		
		public static ulong Swap(ulong value)
		{
			value = (value >> 32) | (value << 32);
			value = ((value >> 16) & 0x0000ffff0000ffffUL) | ((value << 16) & 0xffff0000ffff0000UL);
			value = ((value >>  8) & 0x00ff00ff00ff00ffUL) | ((value << 8 ) & 0xff00ff00ff00ff00UL);
			return value;
		}
		
		public static long Swap(long value)
		{
			ulong uvalue = unchecked((ulong)value);
			uvalue = (uvalue >> 32) | (uvalue << 32);
			uvalue = ((uvalue >> 16) & 0x0000ffff0000ffffUL) | ((uvalue << 16) & 0xffff0000ffff0000UL);
			uvalue = ((uvalue >> 8 ) & 0x00ff00ff00ff00ffUL) | ((uvalue << 8 ) & 0xff00ff00ff00ff00UL);
			return unchecked((long)uvalue);
		}

#if LITTLE_ENDIAN		

		// Host order is little-endian, so these are swaps.
		public static ushort HostToBe(ushort value) { return Swap(value); }
		public static ushort BeToHost(ushort value) { return Swap(value); }
		public static short HostToBe(short value) { return Swap(value); }
		public static short BeToHost(short value) { return Swap(value); }
		public static uint HostToBe(uint value) { return Swap(value); }
		public static uint BeToHost(uint value) { return Swap(value); }
		public static int HostToBe(int value) { return Swap(value); }
		public static int BeToHost(int value) { return Swap(value); }
		public static ulong HostToBe(ulong value) { return Swap(value); }
		public static ulong BeToHost(ulong value) { return Swap(value); }
		public static long HostToBe(long value) { return Swap(value); }
		public static long BeToHost(long value) { return Swap(value); }
		
		// Host order is little-endian, so these are no-ops.
		public static ushort HostToLe(ushort value) { return value; }		
		public static ushort LeToHost(ushort value) { return value; }		
		public static short HostToLe(short value) { return value; }
		public static short LeToHost(short value) { return value; }
		public static uint HostToLe(uint value) { return value; }
		public static uint LeToHost(uint value) { return value; }
		public static int HostToLe(int value) { return value; }
		public static int LeToHost(int value) { return value; }
		public static long HostToLe(long value) { return value; }
		public static long LeToHost(long value) { return value; }
		public static ulong HostToLe(ulong value) { return value; }
		public static ulong LeToHost(ulong value) { return value; }
		
#else

		// If host order is big-endian, then these are no-ops.
		public static ushort HostToBe(ushort value) { return value; }		
		public static ushort BeToHost(ushort value) { return value; }		
		public static short HostToBe(short value) { return value; }
		public static short BeToHost(short value) { return value; }
		public static uint HostToBe(uint value) { return value; }
		public static uint BeToHost(uint value) { return value; }
		public static int HostToBe(int value) { return value; }
		public static int BeToHost(int value) { return value; }
		public static long HostToBe(long value) { return value; }
		public static long BeToHost(long value) { return value; }
		public static ulong HostToBe(ulong value) { return value; }
		public static ulong BeToHost(ulong value) { return value; }
		
		// Host order is big-endian, so these are swaps.
		public static ushort HostToLe(ushort value) { return Swap(value); }
		public static ushort LeToHost(ushort value) { return Swap(value); }
		public static short HostToLe(short value) { return Swap(value); }
		public static short LeToHost(short value) { return Swap(value); }
		public static uint HostToLe(uint value) { return Swap(value); }
		public static uint LeToHost(uint value) { return Swap(value); }
		public static int HostToLe(int value) { return Swap(value); }
		public static int LeToHost(int value) { return Swap(value); }
		public static ulong HostToLe(ulong value) { return Swap(value); }
		public static ulong LeToHost(ulong value) { return Swap(value); }
		public static long HostToLe(long value) { return Swap(value); }
		public static long LeToHost(long value) { return Swap(value); }
		
#endif
		
	}
}