forked from GitHub/gf-core
430 lines
15 KiB
Haskell
430 lines
15 KiB
Haskell
{-# LANGUAGE CPP, MagicHash #-}
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-- for unboxed shifts
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-----------------------------------------------------------------------------
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-- |
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-- Module : Data.Binary.Builder
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-- Copyright : Lennart Kolmodin, Ross Paterson
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-- License : BSD3-style (see LICENSE)
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--
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-- Maintainer : Lennart Kolmodin <kolmodin@dtek.chalmers.se>
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-- Stability : experimental
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-- Portability : portable to Hugs and GHC
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--
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-- Efficient construction of lazy bytestrings.
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--
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-----------------------------------------------------------------------------
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#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
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#include "MachDeps.h"
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#endif
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module Data.Binary.Builder (
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-- * The Builder type
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Builder
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, toLazyByteString
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-- * Constructing Builders
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, empty
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, singleton
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, append
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, fromByteString -- :: S.ByteString -> Builder
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, fromLazyByteString -- :: L.ByteString -> Builder
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-- * Flushing the buffer state
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, flush
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-- * Derived Builders
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-- ** Big-endian writes
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, putWord16be -- :: Word16 -> Builder
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, putWord32be -- :: Word32 -> Builder
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, putWord64be -- :: Word64 -> Builder
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-- ** Little-endian writes
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, putWord16le -- :: Word16 -> Builder
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, putWord32le -- :: Word32 -> Builder
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, putWord64le -- :: Word64 -> Builder
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-- ** Host-endian, unaligned writes
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, putWordhost -- :: Word -> Builder
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, putWord16host -- :: Word16 -> Builder
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, putWord32host -- :: Word32 -> Builder
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, putWord64host -- :: Word64 -> Builder
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) where
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#if MIN_VERSION_base(4,8,0)
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import Prelude hiding (empty)
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#endif
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import Foreign(Word,Word8,Ptr,Storable,ForeignPtr,withForeignPtr,poke,plusPtr,sizeOf)
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import System.IO.Unsafe(unsafePerformIO)
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import Data.Monoid
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--import Data.Word
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import qualified Data.ByteString as S
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import qualified Data.ByteString.Lazy as L
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#ifdef BYTESTRING_IN_BASE
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import Data.ByteString.Base (inlinePerformIO)
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import qualified Data.ByteString.Base as S
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#else
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import Data.ByteString.Internal (inlinePerformIO)
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import qualified Data.ByteString.Internal as S
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--import qualified Data.ByteString.Lazy.Internal as L
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#endif
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#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
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import GHC.Base(Int(..),uncheckedShiftRL# )
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import GHC.Word (Word32(..),Word16(..),Word64(..))
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#if WORD_SIZE_IN_BITS < 64 && __GLASGOW_HASKELL__ >= 608
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import GHC.Word (uncheckedShiftRL64#)
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#endif
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#endif
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------------------------------------------------------------------------
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-- | A 'Builder' is an efficient way to build lazy 'L.ByteString's.
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-- There are several functions for constructing 'Builder's, but only one
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-- to inspect them: to extract any data, you have to turn them into lazy
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-- 'L.ByteString's using 'toLazyByteString'.
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--
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-- Internally, a 'Builder' constructs a lazy 'L.Bytestring' by filling byte
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-- arrays piece by piece. As each buffer is filled, it is \'popped\'
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-- off, to become a new chunk of the resulting lazy 'L.ByteString'.
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-- All this is hidden from the user of the 'Builder'.
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newtype Builder = Builder {
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-- Invariant (from Data.ByteString.Lazy):
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-- The lists include no null ByteStrings.
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runBuilder :: (Buffer -> [S.ByteString]) -> Buffer -> [S.ByteString]
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}
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instance Monoid Builder where
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mempty = empty
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{-# INLINE mempty #-}
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mappend = append
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{-# INLINE mappend #-}
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------------------------------------------------------------------------
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-- | /O(1)./ The empty Builder, satisfying
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--
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-- * @'toLazyByteString' 'empty' = 'L.empty'@
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--
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empty :: Builder
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empty = Builder id
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{-# INLINE empty #-}
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-- | /O(1)./ A Builder taking a single byte, satisfying
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--
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-- * @'toLazyByteString' ('singleton' b) = 'L.singleton' b@
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--
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singleton :: Word8 -> Builder
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singleton = writeN 1 . flip poke
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{-# INLINE singleton #-}
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------------------------------------------------------------------------
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-- | /O(1)./ The concatenation of two Builders, an associative operation
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-- with identity 'empty', satisfying
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--
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-- * @'toLazyByteString' ('append' x y) = 'L.append' ('toLazyByteString' x) ('toLazyByteString' y)@
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--
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append :: Builder -> Builder -> Builder
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append (Builder f) (Builder g) = Builder (f . g)
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{-# INLINE append #-}
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-- | /O(1)./ A Builder taking a 'S.ByteString', satisfying
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--
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-- * @'toLazyByteString' ('fromByteString' bs) = 'L.fromChunks' [bs]@
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--
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fromByteString :: S.ByteString -> Builder
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fromByteString bs
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| S.null bs = empty
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| otherwise = flush `append` mapBuilder (bs :)
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{-# INLINE fromByteString #-}
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-- | /O(1)./ A Builder taking a lazy 'L.ByteString', satisfying
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--
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-- * @'toLazyByteString' ('fromLazyByteString' bs) = bs@
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--
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fromLazyByteString :: L.ByteString -> Builder
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fromLazyByteString bss = flush `append` mapBuilder (L.toChunks bss ++)
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{-# INLINE fromLazyByteString #-}
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------------------------------------------------------------------------
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-- Our internal buffer type
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data Buffer = Buffer {-# UNPACK #-} !(ForeignPtr Word8)
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{-# UNPACK #-} !Int -- offset
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{-# UNPACK #-} !Int -- used bytes
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{-# UNPACK #-} !Int -- length left
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------------------------------------------------------------------------
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-- | /O(n)./ Extract a lazy 'L.ByteString' from a 'Builder'.
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-- The construction work takes place if and when the relevant part of
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-- the lazy 'L.ByteString' is demanded.
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--
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toLazyByteString :: Builder -> L.ByteString
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toLazyByteString m = L.fromChunks $ unsafePerformIO $ do
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buf <- newBuffer defaultSize
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return (runBuilder (m `append` flush) (const []) buf)
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-- | /O(1)./ Pop the 'S.ByteString' we have constructed so far, if any,
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-- yielding a new chunk in the result lazy 'L.ByteString'.
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flush :: Builder
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flush = Builder $ \ k buf@(Buffer p o u l) ->
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if u == 0
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then k buf
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else S.PS p o u : k (Buffer p (o+u) 0 l)
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------------------------------------------------------------------------
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--
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-- copied from Data.ByteString.Lazy
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--
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defaultSize :: Int
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defaultSize = 32 * k - overhead
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where k = 1024
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overhead = 2 * sizeOf (undefined :: Int)
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------------------------------------------------------------------------
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-- | Sequence an IO operation on the buffer
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unsafeLiftIO :: (Buffer -> IO Buffer) -> Builder
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unsafeLiftIO f = Builder $ \ k buf -> inlinePerformIO $ do
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buf' <- f buf
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return (k buf')
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{-# INLINE unsafeLiftIO #-}
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-- | Get the size of the buffer
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withSize :: (Int -> Builder) -> Builder
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withSize f = Builder $ \ k buf@(Buffer _ _ _ l) ->
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runBuilder (f l) k buf
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-- | Map the resulting list of bytestrings.
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mapBuilder :: ([S.ByteString] -> [S.ByteString]) -> Builder
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mapBuilder f = Builder (f .)
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------------------------------------------------------------------------
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-- | Ensure that there are at least @n@ many bytes available.
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ensureFree :: Int -> Builder
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ensureFree n = n `seq` withSize $ \ l ->
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if n <= l then empty else
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flush `append` unsafeLiftIO (const (newBuffer (max n defaultSize)))
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{-# INLINE ensureFree #-}
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-- | Ensure that @n@ many bytes are available, and then use @f@ to write some
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-- bytes into the memory.
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writeN :: Int -> (Ptr Word8 -> IO ()) -> Builder
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writeN n f = ensureFree n `append` unsafeLiftIO (writeNBuffer n f)
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{-# INLINE writeN #-}
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writeNBuffer :: Int -> (Ptr Word8 -> IO ()) -> Buffer -> IO Buffer
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writeNBuffer n f (Buffer fp o u l) = do
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withForeignPtr fp (\p -> f (p `plusPtr` (o+u)))
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return (Buffer fp o (u+n) (l-n))
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{-# INLINE writeNBuffer #-}
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newBuffer :: Int -> IO Buffer
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newBuffer size = do
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fp <- S.mallocByteString size
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return $! Buffer fp 0 0 size
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{-# INLINE newBuffer #-}
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------------------------------------------------------------------------
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-- Aligned, host order writes of storable values
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-- | Ensure that @n@ many bytes are available, and then use @f@ to write some
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-- storable values into the memory.
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writeNbytes :: Storable a => Int -> (Ptr a -> IO ()) -> Builder
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writeNbytes n f = ensureFree n `append` unsafeLiftIO (writeNBufferBytes n f)
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{-# INLINE writeNbytes #-}
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writeNBufferBytes :: Storable a => Int -> (Ptr a -> IO ()) -> Buffer -> IO Buffer
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writeNBufferBytes n f (Buffer fp o u l) = do
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withForeignPtr fp (\p -> f (p `plusPtr` (o+u)))
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return (Buffer fp o (u+n) (l-n))
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{-# INLINE writeNBufferBytes #-}
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------------------------------------------------------------------------
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--
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-- We rely on the fromIntegral to do the right masking for us.
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-- The inlining here is critical, and can be worth 4x performance
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--
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-- | Write a Word16 in big endian format
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putWord16be :: Word16 -> Builder
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putWord16be w = writeN 2 $ \p -> do
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poke p (fromIntegral (shiftr_w16 w 8) :: Word8)
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poke (p `plusPtr` 1) (fromIntegral (w) :: Word8)
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{-# INLINE putWord16be #-}
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-- | Write a Word16 in little endian format
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putWord16le :: Word16 -> Builder
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putWord16le w = writeN 2 $ \p -> do
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poke p (fromIntegral (w) :: Word8)
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poke (p `plusPtr` 1) (fromIntegral (shiftr_w16 w 8) :: Word8)
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{-# INLINE putWord16le #-}
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-- putWord16le w16 = writeN 2 (\p -> poke (castPtr p) w16)
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-- | Write a Word32 in big endian format
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putWord32be :: Word32 -> Builder
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putWord32be w = writeN 4 $ \p -> do
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poke p (fromIntegral (shiftr_w32 w 24) :: Word8)
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poke (p `plusPtr` 1) (fromIntegral (shiftr_w32 w 16) :: Word8)
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poke (p `plusPtr` 2) (fromIntegral (shiftr_w32 w 8) :: Word8)
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poke (p `plusPtr` 3) (fromIntegral (w) :: Word8)
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{-# INLINE putWord32be #-}
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--
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-- a data type to tag Put/Check. writes construct these which are then
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-- inlined and flattened. matching Checks will be more robust with rules.
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--
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-- | Write a Word32 in little endian format
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putWord32le :: Word32 -> Builder
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putWord32le w = writeN 4 $ \p -> do
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poke p (fromIntegral (w) :: Word8)
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poke (p `plusPtr` 1) (fromIntegral (shiftr_w32 w 8) :: Word8)
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poke (p `plusPtr` 2) (fromIntegral (shiftr_w32 w 16) :: Word8)
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poke (p `plusPtr` 3) (fromIntegral (shiftr_w32 w 24) :: Word8)
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{-# INLINE putWord32le #-}
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-- on a little endian machine:
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-- putWord32le w32 = writeN 4 (\p -> poke (castPtr p) w32)
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-- | Write a Word64 in big endian format
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putWord64be :: Word64 -> Builder
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#if WORD_SIZE_IN_BITS < 64
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--
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-- To avoid expensive 64 bit shifts on 32 bit machines, we cast to
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-- Word32, and write that
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--
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putWord64be w =
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let a = fromIntegral (shiftr_w64 w 32) :: Word32
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b = fromIntegral w :: Word32
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in writeN 8 $ \p -> do
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poke p (fromIntegral (shiftr_w32 a 24) :: Word8)
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poke (p `plusPtr` 1) (fromIntegral (shiftr_w32 a 16) :: Word8)
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poke (p `plusPtr` 2) (fromIntegral (shiftr_w32 a 8) :: Word8)
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poke (p `plusPtr` 3) (fromIntegral (a) :: Word8)
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poke (p `plusPtr` 4) (fromIntegral (shiftr_w32 b 24) :: Word8)
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poke (p `plusPtr` 5) (fromIntegral (shiftr_w32 b 16) :: Word8)
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poke (p `plusPtr` 6) (fromIntegral (shiftr_w32 b 8) :: Word8)
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poke (p `plusPtr` 7) (fromIntegral (b) :: Word8)
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#else
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putWord64be w = writeN 8 $ \p -> do
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poke p (fromIntegral (shiftr_w64 w 56) :: Word8)
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poke (p `plusPtr` 1) (fromIntegral (shiftr_w64 w 48) :: Word8)
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poke (p `plusPtr` 2) (fromIntegral (shiftr_w64 w 40) :: Word8)
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poke (p `plusPtr` 3) (fromIntegral (shiftr_w64 w 32) :: Word8)
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poke (p `plusPtr` 4) (fromIntegral (shiftr_w64 w 24) :: Word8)
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poke (p `plusPtr` 5) (fromIntegral (shiftr_w64 w 16) :: Word8)
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poke (p `plusPtr` 6) (fromIntegral (shiftr_w64 w 8) :: Word8)
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poke (p `plusPtr` 7) (fromIntegral (w) :: Word8)
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#endif
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{-# INLINE putWord64be #-}
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-- | Write a Word64 in little endian format
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putWord64le :: Word64 -> Builder
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#if WORD_SIZE_IN_BITS < 64
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putWord64le w =
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let b = fromIntegral (shiftr_w64 w 32) :: Word32
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a = fromIntegral w :: Word32
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in writeN 8 $ \p -> do
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poke (p) (fromIntegral (a) :: Word8)
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poke (p `plusPtr` 1) (fromIntegral (shiftr_w32 a 8) :: Word8)
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poke (p `plusPtr` 2) (fromIntegral (shiftr_w32 a 16) :: Word8)
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poke (p `plusPtr` 3) (fromIntegral (shiftr_w32 a 24) :: Word8)
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poke (p `plusPtr` 4) (fromIntegral (b) :: Word8)
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poke (p `plusPtr` 5) (fromIntegral (shiftr_w32 b 8) :: Word8)
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poke (p `plusPtr` 6) (fromIntegral (shiftr_w32 b 16) :: Word8)
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poke (p `plusPtr` 7) (fromIntegral (shiftr_w32 b 24) :: Word8)
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#else
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putWord64le w = writeN 8 $ \p -> do
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poke p (fromIntegral (w) :: Word8)
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poke (p `plusPtr` 1) (fromIntegral (shiftr_w64 w 8) :: Word8)
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poke (p `plusPtr` 2) (fromIntegral (shiftr_w64 w 16) :: Word8)
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poke (p `plusPtr` 3) (fromIntegral (shiftr_w64 w 24) :: Word8)
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poke (p `plusPtr` 4) (fromIntegral (shiftr_w64 w 32) :: Word8)
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poke (p `plusPtr` 5) (fromIntegral (shiftr_w64 w 40) :: Word8)
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poke (p `plusPtr` 6) (fromIntegral (shiftr_w64 w 48) :: Word8)
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poke (p `plusPtr` 7) (fromIntegral (shiftr_w64 w 56) :: Word8)
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#endif
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{-# INLINE putWord64le #-}
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-- on a little endian machine:
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-- putWord64le w64 = writeN 8 (\p -> poke (castPtr p) w64)
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------------------------------------------------------------------------
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-- Unaligned, word size ops
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-- | /O(1)./ A Builder taking a single native machine word. The word is
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-- written in host order, host endian form, for the machine you're on.
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-- On a 64 bit machine the Word is an 8 byte value, on a 32 bit machine,
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-- 4 bytes. Values written this way are not portable to
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-- different endian or word sized machines, without conversion.
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--
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putWordhost :: Word -> Builder
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putWordhost w = writeNbytes (sizeOf (undefined :: Word)) (\p -> poke p w)
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{-# INLINE putWordhost #-}
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-- | Write a Word16 in native host order and host endianness.
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-- 2 bytes will be written, unaligned.
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putWord16host :: Word16 -> Builder
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putWord16host w16 = writeNbytes (sizeOf (undefined :: Word16)) (\p -> poke p w16)
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{-# INLINE putWord16host #-}
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-- | Write a Word32 in native host order and host endianness.
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-- 4 bytes will be written, unaligned.
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putWord32host :: Word32 -> Builder
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putWord32host w32 = writeNbytes (sizeOf (undefined :: Word32)) (\p -> poke p w32)
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{-# INLINE putWord32host #-}
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-- | Write a Word64 in native host order.
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-- On a 32 bit machine we write two host order Word32s, in big endian form.
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-- 8 bytes will be written, unaligned.
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putWord64host :: Word64 -> Builder
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putWord64host w = writeNbytes (sizeOf (undefined :: Word64)) (\p -> poke p w)
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{-# INLINE putWord64host #-}
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------------------------------------------------------------------------
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-- Unchecked shifts
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{-# INLINE shiftr_w16 #-}
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shiftr_w16 :: Word16 -> Int -> Word16
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{-# INLINE shiftr_w32 #-}
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shiftr_w32 :: Word32 -> Int -> Word32
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{-# INLINE shiftr_w64 #-}
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shiftr_w64 :: Word64 -> Int -> Word64
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#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
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shiftr_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftRL#` i)
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shiftr_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftRL#` i)
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#if WORD_SIZE_IN_BITS < 64
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shiftr_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftRL64#` i)
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#if __GLASGOW_HASKELL__ <= 606
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-- Exported by GHC.Word in GHC 6.8 and higher
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foreign import ccall unsafe "stg_uncheckedShiftRL64"
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uncheckedShiftRL64# :: Word64# -> Int# -> Word64#
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#endif
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#else
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shiftr_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftRL#` i)
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#endif
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#else
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shiftr_w16 = shiftR
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shiftr_w32 = shiftR
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shiftr_w64 = shiftR
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#endif
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