{-# LANGUAGE CPP,FlexibleInstances #-}
module Byte(Byte,Short,Unpack(..),bools2bytes,join8,join16,ord,byte) where
import Data.Word
import Utils2(Split,pieces)

#ifndef __PFE__
import Data.Bits

join8 :: Word8->Word8->Word16
join8 w1 w2 = shiftL (fromIntegral w1) 8 .|. fromIntegral w2

join16 :: Word16->Word16->Word32
join16 w1 w2 = shiftL (fromIntegral w1) 16 .|. fromIntegral w2
#endif

type Byte  = Word8 -- ^ 8 bits, range 0..255 only
type Short = Word16 -- ^ 16 bits, range 0..65535 only

bools2bytes :: [Bool] -> [Byte]
bools2bytes = map packByte . pieces 8
  where
    packByte bits = sum $ zipWith ((*).bit) bits be_bitvalue
    bit False = 0
    bit True = 1

be_bitvalue = [128,64,32,16,8,4,2,1]


class Split bs => Unpack bs where unpack :: bs -> [Byte]

instance Unpack [Byte] where unpack = id

ord c = fromIntegral (fromEnum c)

byte x = ord x :: Byte