+++ /dev/null
-% ------------------------------------------------------------------------------
-% $Id: PrelPack.lhs,v 1.16 2001/01/11 17:25:57 simonmar Exp $
-%
-% (c) The University of Glasgow, 1997-2000
-%
-
-\section[PrelPack]{Packing/unpacking bytes}
-
-This module provides a small set of low-level functions for packing
-and unpacking a chunk of bytes. Used by code emitted by the compiler
-plus the prelude libraries.
-
-The programmer level view of packed strings is provided by a GHC
-system library PackedString.
-
-\begin{code}
-{-# OPTIONS -fno-implicit-prelude #-}
-
-module PrelPack
- (
- -- (**) - emitted by compiler.
-
- packCString#, -- :: [Char] -> ByteArray# **
- packString, -- :: [Char] -> ByteArray Int
- packStringST, -- :: [Char] -> ST s (ByteArray Int)
- packNBytesST, -- :: Int -> [Char] -> ST s (ByteArray Int)
-
- unpackCString, -- :: Ptr a -> [Char]
- unpackCStringST, -- :: Ptr a -> ST s [Char]
- unpackNBytes, -- :: Ptr a -> Int -> [Char]
- unpackNBytesST, -- :: Ptr a -> Int -> ST s [Char]
- unpackNBytesAccST, -- :: Ptr a -> Int -> [Char] -> ST s [Char]
- unpackNBytesAccST#,-- :: Ptr a -> Int -> [Char] -> ST s [Char]
- unpackCString#, -- :: Addr# -> [Char] **
- unpackNBytes#, -- :: Addr# -> Int# -> [Char] **
- unpackNBytesST#, -- :: Addr# -> Int# -> ST s [Char]
-
- unpackCStringBA, -- :: ByteArray Int -> [Char]
- unpackNBytesBA, -- :: ByteArray Int -> Int -> [Char]
- unpackCStringBA#, -- :: ByteArray# -> Int# -> [Char]
- unpackNBytesBA#, -- :: ByteArray# -> Int# -> [Char]
-
-
- unpackFoldrCString#, -- **
- unpackAppendCString#, -- **
-
- new_ps_array, -- Int# -> ST s (MutableByteArray s Int)
- write_ps_array, -- MutableByteArray s Int -> Int# -> Char# -> ST s ()
- freeze_ps_array -- MutableByteArray s Int -> Int# -> ST s (ByteArray Int)
-
- )
- where
-
-import PrelBase
-import {-# SOURCE #-} PrelErr ( error )
-import PrelList ( length )
-import PrelST
-import PrelNum
-import PrelByteArr
-import PrelPtr
-
-\end{code}
-
-%*********************************************************
-%* *
-\subsection{Unpacking Ptrs}
-%* *
-%*********************************************************
-
-Primitives for converting Addrs pointing to external
-sequence of bytes into a list of @Char@s:
-
-\begin{code}
-unpackCString :: Ptr a -> [Char]
-unpackCString a@(Ptr addr)
- | a == nullPtr = []
- | otherwise = unpackCString# addr
-
-unpackNBytes :: Ptr a -> Int -> [Char]
-unpackNBytes (Ptr addr) (I# l) = unpackNBytes# addr l
-
-unpackCStringST :: Ptr a{- ptr. to NUL terminated string-} -> ST s [Char]
-unpackCStringST a@(Ptr addr)
- | a == nullPtr = return []
- | otherwise = unpack 0#
- where
- unpack nh
- | ch `eqChar#` '\0'# = return []
- | otherwise = do
- ls <- unpack (nh +# 1#)
- return ((C# ch ) : ls)
- where
- ch = indexCharOffAddr# addr nh
-
-unpackNBytesST :: Ptr a -> Int -> ST s [Char]
-unpackNBytesST (Ptr addr) (I# l) = unpackNBytesAccST# addr l []
-
-unpackNBytesAccST :: Ptr a -> Int -> [Char] -> ST s [Char]
-unpackNBytesAccST (Ptr addr) (I# l) rest = unpackNBytesAccST# addr l rest
-
-unpackNBytesST# :: Addr# -> Int# -> ST s [Char]
-unpackNBytesST# addr# l# = unpackNBytesAccST# addr# l# []
-
-unpackNBytesAccST# :: Addr# -> Int# -> [Char] -> ST s [Char]
-unpackNBytesAccST# _addr 0# rest = return rest
-unpackNBytesAccST# addr len# rest = unpack rest (len# -# 1#)
- where
- unpack acc i#
- | i# <# 0# = return acc
- | otherwise =
- case indexCharOffAddr# addr i# of
- ch -> unpack (C# ch : acc) (i# -# 1#)
-
-\end{code}
-
-%********************************************************
-%* *
-\subsection{Unpacking ByteArrays}
-%* *
-%********************************************************
-
-Converting byte arrays into list of chars:
-
-\begin{code}
-unpackCStringBA :: ByteArray Int -> [Char]
-unpackCStringBA (ByteArray l@(I# l#) u@(I# u#) bytes)
- | l > u = []
- | otherwise = unpackCStringBA# bytes (u# -# l# +# 1#)
-
-{-
- unpack until NUL or end of BA is reached, whatever comes first.
--}
-unpackCStringBA# :: ByteArray# -> Int# -> [Char]
-unpackCStringBA# bytes len
- = unpack 0#
- where
- unpack nh
- | nh >=# len ||
- ch `eqChar#` '\0'# = []
- | otherwise = C# ch : unpack (nh +# 1#)
- where
- ch = indexCharArray# bytes nh
-
-unpackNBytesBA :: ByteArray Int -> Int -> [Char]
-unpackNBytesBA (ByteArray l u bytes) i
- = unpackNBytesBA# bytes len#
- where
- len# = case max 0 (min i len) of I# v# -> v#
- len | l > u = 0
- | otherwise = u-l+1
-
-unpackNBytesBA# :: ByteArray# -> Int# -> [Char]
-unpackNBytesBA# _bytes 0# = []
-unpackNBytesBA# bytes len# = unpack [] (len# -# 1#)
- where
- unpack acc i#
- | i# <# 0# = acc
- | otherwise =
- case indexCharArray# bytes i# of
- ch -> unpack (C# ch : acc) (i# -# 1#)
-
-\end{code}
-
-
-%********************************************************
-%* *
-\subsection{Packing Strings}
-%* *
-%********************************************************
-
-Converting a list of chars into a packed @ByteArray@ representation.
-
-\begin{code}
-packCString# :: [Char] -> ByteArray#
-packCString# str = case (packString str) of { ByteArray _ _ bytes -> bytes }
-
-packString :: [Char] -> ByteArray Int
-packString str = runST (packStringST str)
-
-packStringST :: [Char] -> ST s (ByteArray Int)
-packStringST str =
- let len = length str in
- packNBytesST len str
-
-packNBytesST :: Int -> [Char] -> ST s (ByteArray Int)
-packNBytesST (I# length#) str =
- {-
- allocate an array that will hold the string
- (not forgetting the NUL byte at the end)
- -}
- new_ps_array (length# +# 1#) >>= \ ch_array ->
- -- fill in packed string from "str"
- fill_in ch_array 0# str >>
- -- freeze the puppy:
- freeze_ps_array ch_array length#
- where
- fill_in :: MutableByteArray s Int -> Int# -> [Char] -> ST s ()
- fill_in arr_in# idx [] =
- write_ps_array arr_in# idx (chr# 0#) >>
- return ()
-
- fill_in arr_in# idx (C# c : cs) =
- write_ps_array arr_in# idx c >>
- fill_in arr_in# (idx +# 1#) cs
-
-\end{code}
-
-(Very :-) ``Specialised'' versions of some CharArray things...
-
-\begin{code}
-new_ps_array :: Int# -> ST s (MutableByteArray s Int)
-write_ps_array :: MutableByteArray s Int -> Int# -> Char# -> ST s ()
-freeze_ps_array :: MutableByteArray s Int -> Int# -> ST s (ByteArray Int)
-
-new_ps_array size = ST $ \ s ->
- case (newByteArray# size s) of { (# s2#, barr# #) ->
- (# s2#, MutableByteArray bot bot barr# #) }
- where
- bot = error "new_ps_array"
-
-write_ps_array (MutableByteArray _ _ barr#) n ch = ST $ \ s# ->
- case writeCharArray# barr# n ch s# of { s2# ->
- (# s2#, () #) }
-
--- same as unsafeFreezeByteArray
-freeze_ps_array (MutableByteArray _ _ arr#) len# = ST $ \ s# ->
- case unsafeFreezeByteArray# arr# s# of { (# s2#, frozen# #) ->
- (# s2#, ByteArray 0 (I# len#) frozen# #) }
-\end{code}
-
-
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