DBus/Types/Endianness.lhs

% Copyright (C) 2009 John Millikin % % This program is free software: you can redistribute it and/or modify % it under the terms of the GNU General Public License as published by % the Free Software Foundation, either version 3 of the License, or % any later version. % % This program is distributed in the hope that it will be useful, % but WITHOUT ANY WARRANTY; without even the implied warranty of % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the % GNU General Public License for more details. % % You should have received a copy of the GNU General Public License % along with this program. If not, see . \ignore{ \begin{code}

module DBus.Types.Endianness
	( -- * Endianness
	  Endianness (..)
	) where

import Data.Word (Word8)
import qualified DBus.Types.Containers as C
import DBus.Types.Signature (mkSignature')

\end{code} } \subsubsection{Endianness} \begin{code}

data Endianness = LittleEndian | BigEndian
	deriving (Show, Eq)

\end{code} Endianness is encoded in the header as a single ASCII character, either {\tt 'l'} ({\tt 0x6C}) for little-endian or {\tt 'B'} ({\tt 0x42}) for big-endian. \begin{code}

instance C.Variable Endianness where
	defaultSignature _ = mkSignature' "y"
	toVariant LittleEndian = C.toVariant (0x6C :: Word8)
	toVariant BigEndian = C.toVariant (0x42 :: Word8)
	fromVariant v = do
		b <- C.fromVariant v :: Maybe Word8
		case b of
			0x6C -> Just LittleEndian
			0x42 -> Just BigEndian
			_    -> Nothing

\end{code}