Network.ByteOrder

Peek and poke functions for network byte order.

Types

type Buffer = Ptr Word8

type Offset = Int

Poking

poke8 :: Word8 -> Buffer -> Offset -> IO ()

>>> let buf = pack [1,2,3,4]
>>> unsafeWithByteString buf (poke8 0)
>>> unpack buf
[0,2,3,4]

poke16 :: Word16 -> Buffer -> Offset -> IO ()

>>> let buf = pack [1,2,3,4]
>>> unsafeWithByteString buf (poke16 (7*256 + 8))
>>> unpack buf
[7,8,3,4]

poke24 :: Word32 -> Buffer -> Offset -> IO ()

>>> let buf = pack [1,2,3,4]
>>> unsafeWithByteString buf (poke24 (6*65536 + 7*256 + 8))
>>> unpack buf
[6,7,8,4]

poke32 :: Word32 -> Buffer -> Offset -> IO ()

>>> let buf = pack [1,2,3,4]
>>> unsafeWithByteString buf (poke32 (6*65536 + 7*256 + 8))
>>> unpack buf
[0,6,7,8]

poke64 :: Word64 -> Buffer -> Offset -> IO ()

>>> let buf = pack [1,2,3,4,5,6,7,8]
>>> unsafeWithByteString buf (poke64 (6*65536 + 7*256 + 8))
>>> unpack buf
[0,0,0,0,0,6,7,8]

Peeking

peek8 :: Buffer -> Offset -> IO Word8

>>> let buf = pack [1,2,3,4]
>>> unsafeWithByteString buf peek8
1

peek16 :: Buffer -> Offset -> IO Word16

>>> let buf = pack [1,2,3,4]
>>> unsafeWithByteString buf peek16
258

peek24 :: Buffer -> Offset -> IO Word32

>>> let buf = pack [1,2,3,4]
>>> unsafeWithByteString buf peek24
66051

peek32 :: Buffer -> Offset -> IO Word32

>>> let buf = pack [1,2,3,4]
>>> unsafeWithByteString buf peek32
16909060

peek64 :: Buffer -> Offset -> IO Word64

>>> let buf = pack [1,2,3,4,5,6,7,8]
>>> unsafeWithByteString buf peek64
72623859790382856

From Word to ByteString

bytestring8 :: Word8 -> ByteString

>>> let w = 5 :: Word8
>>> unpack $ bytestring8 w
[5]

bytestring16 :: Word16 -> ByteString

>>> let w = foldl' (\x y -> x * 256 + y) 0 [5,6] :: Word16
>>> unpack $ bytestring16 w
[5,6]

bytestring32 :: Word32 -> ByteString

>>> let w = foldl' (\x y -> x * 256 + y) 0 [5,6,7,8] :: Word32
>>> unpack $ bytestring32 w
[5,6,7,8]

bytestring64 :: Word64 -> ByteString

>>> let w = foldl' (\x y -> x * 256 + y) 0 [1,2,3,4,5,6,7,8] :: Word64
>>> unpack $ bytestring64 w
[1,2,3,4,5,6,7,8]

From ByteString to Word

word8 :: ByteString -> Word8

>>> let buf = pack [1,2,3,4,5,6,7,8]
>>> word8 buf
1

word16 :: ByteString -> Word16

>>> let buf = pack [1,2,3,4,5,6,7,8]
>>> word16 buf
258

word32 :: ByteString -> Word32

>>> let buf = pack [1,2,3,4,5,6,7,8]
>>> word32 buf
16909060

word64 :: ByteString -> Word64

>>> let buf = pack [1,2,3,4,5,6,7,8]
>>> word64 buf
72623859790382856

Utilities

unsafeWithByteString :: ByteString -> (Buffer -> Offset -> IO a) -> IO a

Using ByteString as Buffer and call the IO action of the second argument by passing the start point and the offset of the ByteString. Note that if a ByteString is created newly, its offset is 0.