module File.Binary.Instances.BigEndian () where
import File.Binary.Classes (Field(..), Binary(..))
import Data.ByteString.Lazy (pack, unpack)
import Data.Word (Word8, Word32)
import Data.Bits (Bits, (.&.), (.|.), shiftL, shiftR)
import Control.Arrow (first)
instance Field Integer where
type FieldArgument Integer = Int
fromBinary n = return . first (wordsToInt . unpack) . getBytes n
toBinary n = return . makeBinary . pack . intToWords n
instance Field Int where
type FieldArgument Int = Int
fromBinary n = return . first (wordsToInt . unpack) . getBytes n
toBinary n = return . makeBinary . pack . intToWords n
instance Field Word32 where
type FieldArgument Word32 = Int
fromBinary n = return . first (wordsToInt . unpack) . getBytes n
toBinary n = return . makeBinary . pack . intToWords n
wordsToInt :: (Num i, Bits i) => [Word8] -> i
wordsToInt = foldl (\i w -> i `shiftL` 8 .|. fromIntegral w) 0
intToWords :: (Bits i, Integral i) => Int -> i -> [Word8]
intToWords = itw []
where
itw r 0 _ = r
itw r n i = itw (fromIntegral (i .&. 0xff) : r) (n 1) (i `shiftR` 8)