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|
module Network.BitTorrent.PeerWire.Block
( BlockIx(..), Block(..)
, BlockLIx, PieceLIx
, defaultBlockSize
, pieceIx, blockIx
, blockRange, ixRange, isPiece
) where
import Control.Applicative
import Data.ByteString (ByteString)
import qualified Data.ByteString as B
import Data.Int
type BlockLIx = Int
type PieceLIx = Int
data BlockIx = BlockIx {
-- ^ Zero-based piece index.
ixPiece :: {-# UNPACK #-} !PieceLIx
-- ^ Zero-based byte offset within the piece.
, ixOffset :: {-# UNPACK #-} !Int
-- ^ Block size starting from offset.
, ixLength :: {-# UNPACK #-} !Int
} deriving (Show, Eq)
data Block = Block {
-- ^ Zero-based piece index.
blkPiece :: PieceLIx
-- ^ Zero-based byte offset within the piece.
, blkOffset :: Int
-- ^ Payload.
, blkData :: ByteString
} deriving (Show, Eq)
-- | Widely used semi-official block size.
defaultBlockSize :: Int
defaultBlockSize = 16 * 1024
isPiece :: Int -> Block -> Bool
isPiece pieceSize (Block i offset bs) =
offset == 0 && B.length bs == pieceSize && i >= 0
{-# INLINE isPiece #-}
pieceIx :: Int -> Int -> BlockIx
pieceIx i = BlockIx i 0
{-# INLINE pieceIx #-}
blockIx :: Block -> BlockIx
blockIx = BlockIx <$> blkPiece <*> blkOffset <*> B.length . blkData
blockRange :: (Num a, Integral a) => Int -> Block -> (a, a)
blockRange pieceSize blk = (offset, offset + len)
where
offset = fromIntegral pieceSize * fromIntegral (blkPiece blk)
+ fromIntegral (blkOffset blk)
len = fromIntegral (B.length (blkData blk))
{-# INLINE blockRange #-}
{-# SPECIALIZE blockRange :: Int -> Block -> (Int64, Int64) #-}
ixRange :: (Num a, Integral a) => Int -> BlockIx -> (a, a)
ixRange pieceSize ix = (offset, offset + len)
where
offset = fromIntegral pieceSize * fromIntegral (ixPiece ix)
+ fromIntegral (ixOffset ix)
len = fromIntegral (ixLength ix)
{-# INLINE ixRange #-}
{-# SPECIALIZE ixRange :: Int -> BlockIx -> (Int64, Int64) #-}
|
