Internal.hs

{-
  Copyright (C) 2009 John Millikin <jmillikin@gmail.com>
  
  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 <http://www.gnu.org/licenses/>.
-}

module DBus.Wire.Internal where
import Data.Word (Word8, Word64)
import qualified DBus.Types as T

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

encodeEndianness :: Endianness -> Word8
encodeEndianness LittleEndian = 108
encodeEndianness BigEndian    = 66

decodeEndianness :: Word8 -> Maybe Endianness
decodeEndianness 108 = Just LittleEndian
decodeEndianness 66  = Just BigEndian
decodeEndianness _   = Nothing

alignment :: T.Type -> Word8
alignment T.DBusByte    = 1
alignment T.DBusWord16  = 2
alignment T.DBusWord32  = 4
alignment T.DBusWord64  = 8
alignment T.DBusInt16   = 2
alignment T.DBusInt32   = 4
alignment T.DBusInt64   = 8
alignment T.DBusDouble  = 8

alignment T.DBusBoolean = 4

alignment T.DBusString     = 4
alignment T.DBusObjectPath = 4

alignment T.DBusSignature  = 1

alignment (T.DBusArray _) = 4

alignment (T.DBusDictionary _ _) = 4

alignment (T.DBusStructure _) = 8

alignment T.DBusVariant = 1


padding :: Word64 -> Word8 -> Word64
padding current count = required where
        count' = fromIntegral count
        missing = mod current count'
        required = if missing > 0
                then count' - missing
                else 0