module Codec.Compression.Zlib.Internal (
compress,
CompressParams(..),
defaultCompressParams,
decompress,
DecompressParams(..),
defaultDecompressParams,
Stream.Format(..),
Stream.CompressionLevel(..),
Stream.Method(..),
Stream.WindowBits(..),
Stream.MemoryLevel(..),
Stream.CompressionStrategy(..),
) where
import Prelude hiding (length)
import Control.Monad (when)
import Control.Exception (assert)
import qualified Data.ByteString.Lazy as L
#ifdef BYTESTRING_IN_BASE
import qualified Data.ByteString.Base as S
#else
import qualified Data.ByteString.Lazy.Internal as L
import qualified Data.ByteString.Internal as S
#endif
import qualified Codec.Compression.Zlib.Stream as Stream
import Codec.Compression.Zlib.Stream (Stream)
data CompressParams = CompressParams {
compressLevel :: Stream.CompressionLevel,
compressMethod :: Stream.Method,
compressWindowBits :: Stream.WindowBits,
compressMemoryLevel :: Stream.MemoryLevel,
compressStrategy :: Stream.CompressionStrategy,
compressBufferSize :: Int
}
data DecompressParams = DecompressParams {
decompressWindowBits :: Stream.WindowBits,
decompressBufferSize :: Int
}
defaultCompressParams :: CompressParams
defaultCompressParams = CompressParams {
compressLevel = Stream.DefaultCompression,
compressMethod = Stream.Deflated,
compressWindowBits = Stream.DefaultWindowBits,
compressMemoryLevel = Stream.DefaultMemoryLevel,
compressStrategy = Stream.DefaultStrategy,
compressBufferSize = defaultCompressBufferSize
}
defaultDecompressParams :: DecompressParams
defaultDecompressParams = DecompressParams {
decompressWindowBits = Stream.DefaultWindowBits,
decompressBufferSize = defaultDecompressBufferSize
}
defaultCompressBufferSize, defaultDecompressBufferSize :: Int
#ifdef BYTESTRING_IN_BASE
defaultCompressBufferSize = 16 * 1024 16
defaultDecompressBufferSize = 32 * 1024 16
#else
defaultCompressBufferSize = 16 * 1024 L.chunkOverhead
defaultDecompressBufferSize = 32 * 1024 L.chunkOverhead
#endif
compress
:: Stream.Format
-> CompressParams
-> L.ByteString
-> L.ByteString
compress format
(CompressParams compLevel method bits memLevel strategy initChunkSize)
input =
L.fromChunks $ Stream.run $ do
Stream.deflateInit format compLevel method bits memLevel strategy
case L.toChunks input of
[] -> fillBuffers 20 []
S.PS inFPtr offset length : chunks -> do
Stream.pushInputBuffer inFPtr offset length
fillBuffers initChunkSize chunks
where
fillBuffers :: Int
-> [S.ByteString]
-> Stream [S.ByteString]
fillBuffers outChunkSize inChunks = do
Stream.consistencyCheck
inputBufferEmpty <- Stream.inputBufferEmpty
outputBufferFull <- Stream.outputBufferFull
assert (inputBufferEmpty || outputBufferFull) $ return ()
when outputBufferFull $ do
outFPtr <- Stream.unsafeLiftIO (S.mallocByteString outChunkSize)
Stream.pushOutputBuffer outFPtr 0 outChunkSize
if inputBufferEmpty
then case inChunks of
[] -> drainBuffers []
S.PS inFPtr offset length : inChunks' -> do
Stream.pushInputBuffer inFPtr offset length
drainBuffers inChunks'
else drainBuffers inChunks
drainBuffers ::
[S.ByteString]
-> Stream [S.ByteString]
drainBuffers inChunks = do
inputBufferEmpty' <- Stream.inputBufferEmpty
outputBufferFull' <- Stream.outputBufferFull
assert(not outputBufferFull'
&& (null inChunks || not inputBufferEmpty')) $ return ()
let flush = if null inChunks then Stream.Finish else Stream.NoFlush
status <- Stream.deflate flush
case status of
Stream.Ok -> do
outputBufferFull <- Stream.outputBufferFull
if outputBufferFull
then do (outFPtr, offset, length) <- Stream.popOutputBuffer
outChunks <- Stream.unsafeInterleave
(fillBuffers defaultCompressBufferSize inChunks)
return (S.PS outFPtr offset length : outChunks)
else do fillBuffers defaultCompressBufferSize inChunks
Stream.StreamEnd -> do
inputBufferEmpty <- Stream.inputBufferEmpty
assert inputBufferEmpty $ return ()
outputBufferBytesAvailable <- Stream.outputBufferBytesAvailable
if outputBufferBytesAvailable > 0
then do (outFPtr, offset, length) <- Stream.popOutputBuffer
Stream.finalise
return [S.PS outFPtr offset length]
else do Stream.finalise
return []
Stream.BufferError -> fail "BufferError should be impossible!"
Stream.NeedDict -> fail "NeedDict is impossible!"
decompress
:: Stream.Format
-> DecompressParams
-> L.ByteString
-> L.ByteString
decompress format (DecompressParams bits initChunkSize) input =
L.fromChunks $ Stream.run $ do
Stream.inflateInit format bits
case L.toChunks input of
[] -> fillBuffers 4 []
S.PS inFPtr offset length : chunks -> do
Stream.pushInputBuffer inFPtr offset length
fillBuffers initChunkSize chunks
where
fillBuffers :: Int
-> [S.ByteString]
-> Stream [S.ByteString]
fillBuffers outChunkSize inChunks = do
inputBufferEmpty <- Stream.inputBufferEmpty
outputBufferFull <- Stream.outputBufferFull
assert (inputBufferEmpty || outputBufferFull) $ return ()
when outputBufferFull $ do
outFPtr <- Stream.unsafeLiftIO (S.mallocByteString outChunkSize)
Stream.pushOutputBuffer outFPtr 0 outChunkSize
if inputBufferEmpty
then case inChunks of
[] -> drainBuffers []
S.PS inFPtr offset length : inChunks' -> do
Stream.pushInputBuffer inFPtr offset length
drainBuffers inChunks'
else drainBuffers inChunks
drainBuffers ::
[S.ByteString]
-> Stream [S.ByteString]
drainBuffers inChunks = do
inputBufferEmpty' <- Stream.inputBufferEmpty
outputBufferFull' <- Stream.outputBufferFull
assert(not outputBufferFull'
&& (null inChunks || not inputBufferEmpty')) $ return ()
status <- Stream.inflate Stream.NoFlush
case status of
Stream.Ok -> do
outputBufferFull <- Stream.outputBufferFull
if outputBufferFull
then do (outFPtr, offset, length) <- Stream.popOutputBuffer
outChunks <- Stream.unsafeInterleave
(fillBuffers defaultDecompressBufferSize inChunks)
return (S.PS outFPtr offset length : outChunks)
else do fillBuffers defaultDecompressBufferSize inChunks
Stream.StreamEnd -> do
outputBufferBytesAvailable <- Stream.outputBufferBytesAvailable
if outputBufferBytesAvailable > 0
then do (outFPtr, offset, length) <- Stream.popOutputBuffer
Stream.finalise
return [S.PS outFPtr offset length]
else do Stream.finalise
return []
Stream.BufferError -> fail "premature end of compressed stream"
Stream.NeedDict -> fail "compressed stream needs a custom dictionary"